Your Stories – Tom’s Maxim Pellet Boiler

There is of course no ONE way and no ONE solution to using less energy.

I invite you to send me your stories about what you are doing.

Here is Tom’s. What is new here is Tom’s choice of a Pellet Boiler. Something like this will be used as an experiment in the French School on PEI. So keeping up with Tom is a good foretaste of how our schools might be heated. It’s also not a system seen here on PEI yet for residential and it will be great to follow Tom and Gail over the winter and see how it works.

Rob Paterson and I have a healthy back and forth.  He, the veritable “Doctor of Doom and Gloom” and I, the “Flower-Sniffing Eternal Optimist”.  We both like to think the truth lies in the middle I imagine…  Perhaps that’s just optimism too.

And so on.

But of all of Rob’s great advice and commentary – yeah, most goes in one ear and out the other –  there was one thing he discussed that rang with clear resonance, clear enough to cut through the ever-present thick fog of this fairyland optimist:   that was his admonishments about “peak oil”.

Woe…  Peak Oil.

The owners of a typical two-story, 2000 square foot house, situated in picturesque Eastern Connecticut, my wife Gail and I have had the increasingly unhappy choir of filling the 250 gallon fuel oil tank that feeds the oil-fired boiler in the basement.    Not ten years ago, we were paying 55 cents per gallon for heating oil.   My last fill-up at US $4.35 per gallon.

Rob was right; oil was getting in short supply…  Soon, we’d see this so called peak oil thing.  Indeed, it was time to revisit home-heating.

To make a long story short (blogs by definition must be short stories)  I ultimately purchased the Maxim 250 pellet boiler. I decided on this system for the following reasons:

–          Fully enclosed and insulated, it can be set-up outside, with just the piping run indoors.  Essentially two pipes, both are freeze resistant and encased in insulating material;  the pipes consequently need not be buried below the frost line.

–          Pellet-fired stoves and boilers vary in efficiency.  The Maxim 250 is rated as 95% efficient.

–          The Maxim 250  is capable of heating upwards of 3000 square feet of living space, including the accommodation for multiple buildings.  Maxim also makes a smaller unit, the Maxim 175.

–          Any pellet will fire in the Maxim…  Corn, wood of any kind, even cherry-pits.  It makes no difference since the temperature is computer controlled.

–          As I mentioned above, water is maintained at a constant temperature.  This, by an onboard computer that automatically feeds the pellets into the fire box at the proper rate.   Incidentally, some pellets burn hotter and slower than others – hence the need for temperature control.

–          I’m configuring my new pellet boiler to work with a heat exchanger that will pre-heat the water that’s fed into my oil-fired  boiler.  When properly set, the pellet boiler will keep the water hot enough to preclude the oil-burner from firing.  If the pellet boiler ever fails – no problem; the oil burner will start as it would normally.  The device can configured for all the usual heating applications such as, forced hot air, radiant heat, and so on.

That’s it for the device…  Now the metrics.

–          We estimated that it would cost $4000 to heat the house with oil this winter.  That assumes oil prices remained in the $4.00 per gallon range, we experience a normal winter, and we heat the house to temperatures as is our custom.

–          Based on the current price of pellets, and in consultation with the pellet stove dealer who sold me the device, we estimated that we would use approximately $750.00 pellets, not only for the winter, but for an entire year.  Here’s a link to a calculator that helps calculate savings based on existing heating and hot water costs.

–          The boiler costs $8500 delivered,  and with installation, we expect to have invested $9,200.  Here’s a link to a quick video that describes the system set-up.

Here are a few other options I considered.

–          Pellet stoves…  This was my first idea.  The prices range from $2500-$5000 depending on capacity and so forth.  In the end, you end up with a convection hot air system that dries out the air, creates drafts (as it pulls in fresh air from outside).  And a fire source inside the house.

–          Word burning boilers.  Vastly inefficient and just as costly, these systems pollute the neighborhood and require stacks of cord-wood in your yard.  Moreover, keeping these systems stoked takes time and effort.  On the bright side – they’re the cheapest option ($850-$3500).  Here’s a link to a number of outdoor wood boilers.  A little less money to buy, perhaps more expensive to fuel.

–          Electric Heat…  Operating costs seem lock-stepped with oil…  What would be the point.

–          Geothermal…  I read something on Rob’s Blog about up and coming Geothermal.  It looks rather promising, but requires lots of deep trenches to fit huge arrays of cooling pipes.  Nah.  Too much of a science project for me.

Seth Godin wrote in his blog the other day, that sometimes fixing one thing makes all the difference.  He went on to opine how one company could make some changes to its customer service, how another needs to work on its waiting times and lastly, Joe Biden needs to work on his brevity…

I thought if I could fix one thing at home, it would not be purchasing a hybrid car, getting a solar array or installing a wind farm – it would be this pellet furnace.  Just knowing that I wont be sending $4000 dollars to the middle east this year is indeed a comfort.

PS Neither Tom or I have any interest in Maxim – this blog will be frank about products and services but is not in any way connected to any other than as fellow users


126 responses to “Your Stories – Tom’s Maxim Pellet Boiler

  1. I neglected to include the link to the other wood boiler options:

    also, beware of outdoor systems that feature water cooled doors. You should ask yourself: what would a well insulated system need a water cooled door for?


  2. Those are some very impressive and worthwhile savings!

    Do you have any idea what you expect to happen to the price of pellets as more people get onboard with this type of heating?

  3. I guess this is not an interactive forum 🙂

  4. Matt – I have been busy on my other stuff – At the moment there might be a bump in proce as capacity has not grown yet

    Hoping on PEI that we can do for pellets what we did with wind – have the govt use them to heat govt building such as schools – create the demand and set up a local system here

    So back to you Matt what do you think – after why should I now any more than you?

  5. Well, I would assume that when supplying things locally, the market is more susceptible to price shocks. Also, one of our ongoing problems is that we don’t seem to take reflexivity into account and seem to assume that a situation will stay the same when we add our own self to that situation.

    The idea that, for example, we should move toward electric cars because electricity is so relatively cheap. Well, will it be so cheap when 20,000,000 people are trying to power their cars with it?

    There’s a similar argument to be made here — can PEI affordably supply the heating needs of its population with wood pellets in a sustainable way? Or will it get a tenth of the way in and start getting price shocks?

    Environmentally-speaking, it’s not as simple as cutting down trees in one area and then replanting them in another because erosion and other ecological destruction occurs while the ground cover is gone from the cut site. You can use waste products from operations that would go forth anyway, but when your demand for waste exceeds the supply of waste, what happens then? Similar to the gasoline/diesel problem, where a refinery produces related amounts of each in the fractionation process.

    Also, there is no such thing as a waste product. What isn’t returned to the ecosystem doesn’t magically reappear somewhere else. Organic farmers know this and return compost and manure to the soil, while the others use artificial fertilizers to restore the nutrients that the plants most apparently need.

    As for why you should know any more about wood pellet prices than me… well, you have ideas about oil prices, don’t you? And I don’t know of anyone seriously looking at wood pellets because we don’t have the degree of heating oil dependency that you have on PEI.

    Maybe I’m going off-topic… this blog might just be about kickstarting plausible alternatives to oil…. in which case, it’s a great summary of the options. I knew about wood pellet stoves, but I didn’t know you could get boilers that run from them, too.

  6. I have bumped into a great resource on how wood may be used locally – Roy MacMullin – I will be posting some of his material asap – Roy is looking at the issue you bring up – can we use wood as a sustainable alternative? His answer is yes

    More later..

  7. Thanks, Rob. Looking forward to it.

  8. Sorry for the delay – pellet prices will be slowly dropping I surmise – the US has 800,000 households using pellets right now; as more households start using pellets demand will rise, but so wont supplies.

    $700 worth of pellets per year heats the house! At that price – leave the windows open!

  9. Well, I wouldn’t go as far as that — $700/year is what I paid to heat my house and water with natural gas last year, and I in no way feel inclined to leave the windows open 🙂 That was a 1960s attitude that I hope we can bury!

    Can these stoves burn wood, too, or be converted to woodburning stoves? My instinct says not, because I’ve heard things here and there about the pellet idea… but maybe it has advanced?

  10. HELLO, I am wondering if you already had your maxim 250 installed. I am looking to get the same one, I am being told they do not ship until october, and I am getting estimates of 2 to 10 weeks for delivery. What was your experience with delivery time and also with installation? Thank you! CM

  11. Matt – Pellets only, however, there are stoves that will burn both; they’re just mediocre pellet burners though.

    CM, I ordered my boiler July 2-3 and expect delivery Mid-October. I’m hearing that people who are trying to order now are out of luck.


  12. I was wondering about how the Maxim water lines enter the house? Though the foundation?

  13. The piping typically goes through the foundation. Do you have any “knock outs”?

    Another option is through a basement window or through the side of the house and down.

    The piping consists of two 3/4 k-pex lines encased in a 4″ poly-insulating flexible pipe. The outer pipe is terminated at the side of the house and only the two 3/4 lines penetrate.

    Hope this helps –

    My boiler’s delivery has been delayed until the end of Oct – the company is being flogged to death apparently.


  14. Update…
    I got the so-called flexible pipe and buried it 16″ deep. It does not require burying below the frost line.

    Its not very flexible – you’ll get quite a work out. The upside, you certainly dont want to pay a plumber $60 an hour to dig a hole and bury a pipe.


  15. Update…
    The plumber installed the heat exchanger and recirc pumps; all is now in readiness for the boiler. I’m hopeful that it will arrive 7 or 8 Nov.


  16. Good luck with the boiler. Right now I hear pellets are scarce (purchased mine for the pellet stove in May — tax check from Bush). I would suggest that you set aside a few more greenbacks for more pellets. I found that the calculators are “optimistic” at best. I live in Central CT in a slightly larger house and we just purchased 5 tons of pellets based on our 3 year history with the pellet stove. We had in the past used between 1200 and 1500 gallons of oil. Using the Btu content of the pellets (~8000 Btu/lb) and subtracting out the 300 gallons of oil we still used last winter (weekends away, really cold nights, etc.) assuming we offset about 1000 gallons of oil:

    8,000 BTU/lb
    2,000 lb/ton
    16,000,000 Total Heat Content
    85% Efficiency of Stove
    13,600,000 Total Heat per Ton (Btu)

    1,000 gallons of Oil
    139,500 Btu/gallon of #2
    139,500,000 Total Heat of Oil
    65% Assumed Efficiency of Oil
    90,675,000 Total Heat Required

    6.67 tons Pellets Required

    Sanity Check:

    2,400 Sq. Feet
    25 Btu/Sq Feet (Peak)
    2,000 Total Full Load Hours
    120,000,000 Total Heat Required

    My experience has been that we have used between 4 and 5 tons of pellets depending on how late into the spring we need to take the edge off. Granted my old house (1939) is not well insulated, not every window has been updated and we are slowly decreasing the temperature of the house but the btus are the btus and I think the pellet stove salesman at least under sell the amount of pellets required.

    Please update next spring with your experience and pellet use.


  17. I have a Maxim 175. I had it installed the first week of October, and everything started off fine. I buried the Pex myself, borrowing a friend’s skid-loader. I am heating a total of approximately 3500 sq ft to 64F,and 1200 sq ft to 68-70F between 2 buildings, all radiant floor heat.

    I have noticed that the system is very erratic in it’s pellet consumption. Regardless of outside temp, one day it uses 40# of pellets, the next is 80-100#. I have poured over the owner’s manual, but it doesn’t offer any insight to system setup, beyond a very elementary level.

    Does anyone here have a good place to start for water temp settings or fan speed? Also, my unit has a “clean out” function noted on the electronic control pad, but I can’t figure out what it’s for or how to operate it.

    I have noticed that the unit does just as good heating my buildings with the water temp set at 155 as it does at 170. Is there a reason the manual suggests a minimum temp of 165?

    As for fuel supply, I have purchased 3 pallets of pellets (170 – 40# bags) from Menards at a cost of approx $720. I have used almost 35 bags in the last 3 weeks, so I’m pretty sure I’ll need more to get through winter. Still, it will be much cheaper than natural gas like last year.

    If anyone has some ideas on system setup or placs to buy pre-packaged fuel, please respond.


  18. Darren, I’m not an expert, but I suspect two problems:
    – You’re trying to heat too much space.
    – You need a professional to adjust the computer controls.

    Turning down the water temperature just means the water will circulate longer through the pipes before the room reaches temperature.

    Good luck!

  19. Darren , I also have the maxim 175. I live in vermont. i am usin two bags a day to heat 1450 of house and 990 of garage. I also want to know about the clean out mode. Have called my dealer still waiting for my answer been a week. I would like to clean out tubes. As you said the manual is not very helpful.

    Thanks Sctt

  20. Can anyone tell me how much it costs to install the boilers?

  21. mine was around 2000.00 This inclued modine in the garage. 3 circulaters interior pipe and 2 guys for roughly 8 hours

  22. we have one now and it did real good on the pellets but I am looking at a lot of partly burned corn now, and I don’t want to be ccleaning it out every day – we have a thing that is above and beyond the manual but still not very helpful, tells you how to cchange a lot of settings but not WHY so if we have any experts stumble in, give us a clue

  23. Thanks Scott…I am doing some research on pellet boilers and looking for as much information as I can get however I am in Newfoundland Canada and was hoping for something closer to home.

  24. I also have a maxim 175 and have found it to be a little of a let down . It heats great but is producing quite a bit of smoke at idle and at initial change of levels , saying going from idle to medium it will belch a huge plume of smoke for 5 to 10 seconds and then smoke a bit untill the fire really gets going then all is well . I have also found the fire box gets dirty as hell FAST and has some tar like substance under the fire pot anyone have any insite ?

  25. UPDATE, I have found that your fan setting has to be atleast equal with the pellet feed rate in any given setting IE ( idle , med , high ) this has taken care of the tar issue and to my surprise I had the feed rates too high ( idle was 4 green , med was one red , high was 3 red . ) now my setting for heating a 2 zone 2300 sqft split level house with a huge basement home theater room (almost the entire basement ) is 2 green for idle 4 orange for med and 1 red for highfor feed rates and the fan rates are 2 green for idle 1 red for med and 1 red for high and so far the only time it has gone into the high setting is when both zones were calling for heat and the wife was in the shower other than that it stays in the idle or med setting . I have my water temp set at 180 and it settles at 181 and when its circulating for heat it drops to 177 and then fires to med for 2 to 4 minutes and then back to idle the lowest I have seen the temp drop was when both zones were circulating and the shower was in use and then it only dropped to 175 . my set up is running through the exsisting presurized boiler ( now depresurized) with one circulator on the maxim I did however slightly close the ball valve on the return line to the maxim to achieve 5psi of line pressure to aid in heating the house and relieving some strain on the inside circulators . the outside circulator has a bit of strain from the slightly closed valve but I have a spare and they are not that expensive . as for install prices, for what actually had to be done for my system was around 300.00 a buddy and myself did everything except coreing the hole in the foundation and that was an additional 300 so a total of 600 and I was done 2000.00 is outragous you can do most of it yourself DO NOT BE AFFRAID . it a good learning experience any questions can be asked by Emailing me at

  26. Wow – good stuff here! I’m now 6 weeks into my Maxim 250 experience. the boiler cost me about 9K with the parts needed to exchange heat with my oil boiler. Labor was $400. I dug the hole myself, poured the slab and roughed out the electic myself.

    I went through 1 ton of pallets in November and expect to do likewise in December. I paid $280 for a ton of pellets at Tractor Supply.

    My biggest problem is the creosote. (tar substance). I’m seeing allot of it; its actually dripping from the chimney and seems to be caused by the the stack being too cool.

    Here’s what the reas situation is: no one knows how to install them and no one knows how to adjust them. This is actually the only place I found with info – particularly Mike C. above.

    Mike – good info on settings!!!

  27. I have a maxim 175 unit. Today i expericend smoke coming from hopper. The unit was on high. I clean around burner. and cleaned the exhuast tubes. This is the first time this has happened. After i cleaned it there is no more smoke. I cleaned the exhaust after the first ton i burned. Has any one else had this happen. Thanks Scott

  28. Scott,
    sounds to me by what you saying is that you had slightly clogged exhaust outlet issue . if your maxim isnt burning clean enough its going to need cleaning quite often and make no mistake if its dirty and the transfer tubes are not clear you will have reversion of exhaust gas through the feed system ( which isnt good at all ) try adjusting your settings to the lowest feed rate you can get away with and still have the temp and volume of heat you need with the fan speeds at the same setting then bring your fan speed up one notch and report back I’ll bet you will be happier for it . and remember more is not always better and air when it comes to solid fuel combustion = heat
    first off what pipes are you using ? the ones that came with the unit or did you add more ? if your using the class A vent that came with the unit then all the heat is being contained within the pipe and keeping stack temp high which should not pose any problems if this is the situation then I would try to lower your feed rate and or increase your fan speed . creosote is a product of substandard material being burned IE pine , soft wood, crappy pellets . OR inefficent burning of the materials being burnt ( not enough air ) or too much material being fed to the given air available . today the high was 21 degrees . my downstairs thermostat was set on 68 and the up stairs on 66 temp of house stayed constant and comfortable my settings are even lower than before 2 green for idle 4 orange for med and 1 red for high I lowered the fan speed for med just one and the boiler never went below 177 ( set to 180 ) and as far as I could see it never went into high and only burned about 1.5 bag the ash content went down a bit and the creosote is almost gone from the burn chamber all but just a light film that has been crusting up and flaking off
    Hope this helps … I am by no means an expert on the maxim 175 ( as I am still learning as well ) but you could say I am a bit anal when it comes to machines and the like . I have to be in my business. its not easy getting a 1400 cc 4 cylinder engine to spin at 13 to 14000 rpm and make 400 to 550 hp and stay togather while doing it factory certified Suzuki , Kawasaki, Ducati tech and a damed good one at that 🙂

  29. Yes i can see where i have a creosote build up. On my settings i have no red color. I have the green and orange but no red. Can you tell me how manyabove the green you are at. I put in 3 bags tonight. So i burned 3 bags in a day

  30. Hello
    I just started up my 250 today. And very impressed with the unit, But I think I have to play with the settings a little. I agree with you Mike C. you have a lot of good points. It is really warn up here in Ontario Canada this weekend(+10’C) and it is not taking much to heat my house. But I am really impressed with the lack of smoke I am seeing coming from the unit, when under fire. But it does smoke a little on Idle which surprised me and when It changes from say idle to med. but I think i can get that worked out. But I first start, it smoked for 5 minutes and then you could not even til it was running when it was trying to get up to temp. for the first time.
    I really like the unit, that modulating feed rate and air is great, the hopper is a nice size and that propane start is awesome. I hope it works as good as I think it is going too.
    Happy New Year everyone.

  31. Just wondering how everybodys units are working. Did you find any new things to tweak the unit to make it preform better. I am burning 3 bags a day.

  32. Hello
    I am burning 100 pounds of pellets a day and it works great. Ash once a week and clean the flues every other week.
    I have mine set all feed rates at 4 green and the air settings one above that.
    Seems to burn very clean and the ash is like dust. So I think I have it working good.

  33. Changed my thinking.
    Maybe a higher fan rate makes heat out the chimney.S o I have adjusted it and went with 2 setting below the feed rate with the air fan setting. seems to smoke more but the burner temp is high so that should be good I think so . we will try it for a few days and see.

  34. Hello!

    I’ve installed the M250 last week. I burned 1654 gals of propane last year for $3969.oo, so it was time to make a change.

    I’m really confused about the auger/fan settings. I started a spreadsheet to track how much I’m burning compared to the Heating Degree Days, and so far nothing seems to be better than the factory settings. I’m burning 5 bags (200 lbs) of pellets a day, so I’ll go through a ton in 10 days. Even with that it’s going to save about 50% since I got the pellet for 150/ton. Anyway I’m getting a wierd black “cake” in my burn pot, and black build-up all over the inside of the burn chamber, and almost constant smoke. Any thoughts on what I might try to improve my burn efficiency?

  35. Jeff how is it going? I have my fan at two above feed rate. No smoke burning 3 bags a day when temps in the teens. was wondering how you are doing with the latest settings. I have to clean my flue every half ton or get smoke coming up in the pellet hopper.


  36. found somewhere in the middle is the best.
    with the feed rate higher then the air speed I got a lot more ash(Whole pellets) and also a lot more smoke. So know I have adjusted again and went with:High 4 green feed and 2 yellow air(more air on the high)
    Medium 4 green feed and 4 green air
    Low 2 green and 2 green
    Like how it is burning.
    I feel if you have black fire box(sticky like)
    you have to much feed and not enough air
    same thing if you have a lot of smoke

    It is something you really have to play with
    have fun

  37. I have a Maxim 250. After about two months of getting to know it I had to be away and shut it down. I had antifreezd it to make this possible. I shut off powere to the unit so that the circulation pump would not run the whole time. While I was away the unit back burned up the augers and into the storage bin doing extensive damage. Has any one else experianced this problem perhaps during an extended power outage?

  38. Tony sorry to hear about your problem. Iread on another forum i burn corn i think about the burn back. he posted pics. of it. CB was going to cover it.

  39. Has anyone burned pellets year around to heat there water. was wondering what your consumption was? Thanks Scott

  40. The 90 gallon water capacity of the Maxim does not make it very efficient for heating domestic hot water in the summer. What would be great would be a small pellet fired domestic hot water maker similar to the small wood fired ones that are available.

  41. About the back burn problem. The Maxim 250 has two feed augers. The upper one brings the pellets off the bottom of the hopper and ‘drops them onto the lower auger which pushes them directly into the burn pot. This drop zone between the augers was designed to creat a break in the contact between pellets leading from the burn pot back to the hopper. This drop zone can become full of pellets if there is any resistance to the lower augers delivery of the pellets to the burner. Once this drop zone is full of pellets there is a direct line of fuel all the way to the hopper.
    CM built in a safty feature whic only works when there is power to the Maxim. There is a heat sensor in the lower auger area which will acyivate if there is excessive heat in that area. This triggers the lower auger to advance pellets without the upper auger running which clears the area of the back burning pellets and af any excess pellets in the drop zone. This is the same thing that occures when the clean out function is employed.
    All of that is fine if there is power to the unit. During a power outage it does not take very many hours for the fire to make it all the way to the hopper and to melt all the controles mounted in that area. If I had known to keep the drop zone clear which can be inspected through the glass in the drop zone the back burn would have been limited to the lower auger and would have done far less damage.
    The Owners Manuel hopefully will be urgently updated with warnings about how to avoid this ‘problem’. Other boilers have longer drop zones, or a rotery paddle wheel instead of the upper auger. The paddle wheel avoids the connected spirel of fuel that an auger creates.

  42. I run an M175 in northern Minnesota. We had a very cold winter (Between -20 and -10 at night seemed normal). I burned about from 1.5 to 4 bags a day heating my well insulated 3600 sq ft house/basement and a 2 stall attached garage. I used a total of 8 tons from October 15 to April 15, oh, and about 20 bushels of corn just to try it.

    From what I’ve read, if you have wet sticky black creosote, it means that your unit is not burning hot enough. It either means that it is warm outside, your heat load is small, or your air settings need to be increased some. Creosote can also be caused by running your water temperature too low. The walls of your firebox are cold, and the fire is hot, so that can cause creosote. The less difference between the heat of the fire and the temp of your firebox walls will lessen the creosote too. Run your water temp at 175 instead of 150 and see if that will decrease the creosote. But I say again, if it is warm out so your heat load is low, you will most likely see creosote no matter what because your unit is idling for long periods of time.

    As far as the hard flakey crust in the burn pot, it is TOTALLY dependant on your quality of pellets. I ran some pellets for a while that caused large solid crust pucks, and then switched to another brand that would leave only a fine light gray dust. I would not be too concerned with the crust pucks though, just pull them out every 3 or 4 days and you will be fine. But I say again, the crust pucks have 90% to do with your fuel quality, and probably 10% to do with your feed/fan settings.

    Corn, even when “completely” burned would leave a lot a ash clinkers, so I had to scoop out ash clinkers every 3 or 4 days. Pellets I probably only would have had to scoop out ash every month (I did it every 2 weeks anyway).

    Don’t ever unplug your unit unless you scoop all of the burning embers from your burn pot. There are safety features built in to prevent back burn. Or I guess you could run the unit in “clean out” mode too before unplugging it to be sure that there are no pellets in the auger to back burn into. But BEWARE that if you unplug your circulating pumps that you run the risk of the pipes freezing too unless you have treated the system with antifreeze (expensive!).

    I loved my Maxim 175 this heating season. I had a total of 2 small metal garbage cans of ash for the entire winter.

    Pellets cost me an average of $230/ton for the season including the fuel for my 30 mile round trips to pick them up. My pellets were in individual bags. My 20 bushels of corn was $3.00/bushel at the local elevator at 15% moisture and it burned fine.

  43. oct 11 2009, fired up the 175 today. so far so good

  44. Hey all,
    I have a 250. I had the back-burn problem last winter (March 2009) that ruined my boiler. Maxim and my dealer delivered a replacement boiler and picked up the old one. I had to do all the disconecting and reconnecting. I am looking forward to the coming season and appreciate this blog to keep in touch with other owner-operators. Maxim deffinately needs to upgrade its manuel in the area of ‘back-burn causes and prevention’. The electronic over-heat sensor near the lower auger can take care of a back-burn while the unit is powered. The danger is when the unit is deprived suddenly of power as in a power outage. IF POWER IS NOT EXPECTED TO RESUME WITHIN A SHORT TIME, ALL BURNING FUEL SHOULD BE RAKED AWAY FROM THE BURN AREA AND THE ENTRANCE TO THE LOWER AUGER. It takes only a few hours for the fire to smolder its way up the lower auger over heating that area. In my case the drop zone between the upper and lower augers had become full due to some sort of resistance in the burn pot, so the back-burn continued all the the way to the hopper. All should know the function of the clean out mode. Part of weekly inspection should be to inspect the drop zone through the glass window. You will always see the pellets held by the upper auger poised to fall through the drop tube to the lower auger. Be familiar with this and look for a pile of pellets filling up the tube. If the drop tube is full of pellets, run the clean out mode for a short tome to clear the extra pellets. The clean out mode runs the lower auger with out running the upper one. Always run the clean out mode before shutting off power to the boiler for more than a short time. Sorry so wordy but an important topic. I enjoy all of the posts about power settings etc… Tony

  45. Hello from Ontario, Canada,

    I have a M175 Maxim and I’ve had it for a year now. I am heating 3000 square feet to about 72F during the day and 68F at night. I am heating a large oil fired hot water tank and my heat is forced air hot water which is taken from the hot water tank via a circulating pump. I too had to learn the hard way, how to best set-up and maintain this unit. The settings depend on the quaility of the fuel used; if it contains too much moisture as is the case with new corn or poor quaility wood pellets, more air will be required to keep the fire from going out and/or to burn more efficiently. The factory settings is a good starting point, the air settings should always match the feed settings if the fuel is dry. If the fuel is a little wet, then the air settings should move one or two above the feed settings. My water temp is set at 170; I have tried lower temp settings, but it seems to burn cleaner at higher temp settings. If the temp setting is much higher it just burns more fuel. I have burned both corn and wood pellets, but last year corn was cheaper than wood pellets so I burned mostly corn. Now corn is a bit messy and the moisture content seems to vary; my solution is to mix the two (80% corn 20% wood pellets).

    Cleaning – Keeping this unit clean is very important, most of the problems associated with high fuel consumption is directly related to a dirty unit. Here’s my cleaning routine:

    Daily- (5 mins) scoop ashes from the ashe bin. Using the stir rod, scrape the burn pot to loosen any clinkers (mostly from corn). note, don’t put the fire out; wait until the unit changes to Med when your doing this is better.

    Weekly- (30 mins) The tubes should be cleaned out with the small round brush once a week, it takes only 10 mins to clean them out if its done weekly. The clean out mode should be run and inspect the drop zone through the glass window. (some units just have a screw-in round plug) it should NOT be full of pellets; if it is, run in clean out mode again. Using the stir-rod, scrape under the burn pot to remove ash and crusties.

    Monthly – same as weeky, except I remove the burn pot and stirrer, and empty the ash that has fallen through the holes in the burn pot; the white gasket at the back of the burn pot usually sticks to the pot itself, if it’s damaged replace it with a new one, they are cheep. Before you remove the burn pot, make sure you have a new gasket, just in case; order 3 or 4 at time. To make it easier to install the burn pot, the gasket can be held onto the burn pot with a few dabs of high heat gasket cement. Before installing the burn pot, use a long handled scraper and clean under and above where the burn pot sits. Also clean the chimney with a brush.
    END of the year- empty the bin of all corn and/or wood pellets, then clean everything twice. Once everything is as clean as possible, spray everything inside the unit with rust-proofing spray; I used rust check (red can). If the unit is hard to scrape or get clean, spray it with rust-proofing and let it sit for a week, then clean it again. In the fall at first start-up it will only smoke for about 5 or 10 minutes if there is a lot of oil still on the metal surfaces. Also before firing up the unit for the first time in the fall, check the air intake; mud wasps and mice like to make nests in this area. There is a metal flapper over the air intake on some models, shipped last year; Maxim is recommending that everyone remove this metal flapper as it can stick closed sometimes, which in turn will make it impossible to adjust the settings for your fuel.

    One last note, when the weather is warm, the unit is in idle for long periods of time; this will cause your unit to get dirty very quickly and waste fuel. When it’s above 45-50F during the day, I shut down my unit for the day and let my back-up take over. To properly shut down, do the following:
    1. run on clean-out mode for 10 mins; this will stop burn back.
    2. pull all of the fuel and ash out of the burn pot.
    3. power unit down with the power switch; the cirulating pump to the house will still run. If you don’t want your back-up to heat your unit, unplug the cirulating pump at the unit or shut off the circuit breaker. Note the burn back protection will not work with the breaker turned off, that’s why I run the unit in clean out mode for 10 mins before turning off the unit.

    Settings that I have right now with farely dry corn (80% corn 20% wood pellets are:
    low- two green
    Med- one yellow
    High- one yellow
    Low-two green
    Med – 1 yellow
    High- 1 yellow

  46. Scott BOnneville

    Very nice paul, i appericate the post you amde. it is very helpful. This is my second year burning my 175.
    Thanks Scott

  47. No problem Scott, tips from anyone is all good. I think everyone agrees that the book/info that comes with the unit is useless; however I beleive the quality and design of this unit is better than most and with a bit of experience you will save a lot of $ in heating costs. I am thinking about adding a second cir pump and heat exchanger to heat my pool, has anyone out their done this; if so what does it cost for the parts etc and how well does it work? Also has anyone out there experimented with burning other fuels like soy beans or wheat?

  48. Hi from Dundee, Quebec.
    Paul, I am burning 6 yr old moldy buckwheat in our first year with the 175 , working well desipite a few extra ashes. Had to increase feed rate and decrease air rate to avoid blowing burning grain out of the firepot.
    We have CB bin extension with autofeed auger. The grain is light and dirty, germination almost zero and the birds and mice won’t even eat it. The furnace however seems to be happy and is using lots of it daily with temp. set at 180, making no smoke. We have 14 tonnes in a hopper bin which I have wanted to empty but hated to throw buckwheat away. Heating the house with it makes more sense, so far so good anyway.

  49. Has anyone tried slowing down exhaust gas escape by putting a restricter in the flue pipe.There is no smoke produced burning grain but a lot of heat is going up the chimney. A six inch flue seems excessive for the size of the fire in the M 175 so I made a tin disc with an adjustable flap in the center, shoved it into the base of the chimney reducing diameter by 50% hoping to slow exhaust movement through heat-exchanger tubes. So far we have an increase of 15 degrees at the same fuel and air settings. Seems to be working well, wonder if I should reduce further? Anyone have any experience with this? Any comments would be appreciated.

  50. Some great post out there. I have the M175 and this is my second year with it. I have had all the same questions and issues that everyone else has mentioned, the tar like creosote, the extra smoke when in idle mode for long periods and I even had a litle back burn problem when the power went out for a few hours, but the only damage was to the snap disk which was replaced by the dealer at no cost to me. Adjusting the feed rate and air helped with the other issues. And my pellet consumptions does seem to fluctuate sometimes regardless of the temparature. Last year at the end of the season, I did have the auger(aerator) in the burn chamber melt in half and again was replaced by the dealer in which he told me that he has heard about a few of these and CB had a modification in the works in which I would receive an additional auger, but I have yet to hear anything else about this. I do have aa questions for anyone who may have this problem. I have it setup so that it is running through the exsisting pressurized boiler (now depresurized) with one circulator pump inside. The run is very short as the maxim is right outside on the other side of the wall and just a couple feet above. I heat with baseboards. When my thermostats reach the desired temparature and stop calling for heat the entire baseboard loops bangs loudly. this does not happen when I just run my regular furnace without the maximm as i did until December. I have had my furnace guy over twice now and when he leaves it is better for a day but just goes back. He is unsure why it does this as he does not know much about the maxim. He has tried bleeding the system of air several times. Does anyone else have this issues or have any suggestions.

  51. scott bonneville

    i got a notice from my dealer. If your unit is installed inside a building they will install a Thermal Valve. It will release a small amount of waterinto the burner auger to cool the area, In case of power outage.

    Has anyone else got a letter from there dealer.

    Thanks Scott B

  52. Just had a 24 hr power outage due to a storm and I was not around when it happened. The stove backburned all the way into my hopper and when I came home found the hopper smoking. The hooper was about half full. When I lifted the lid to let the smoke clear all the pellets were charred and the hopper pellets burst into fllames with a minute. I have black sticky creasote coming out every edge of the stove. I see Tony had this issue last March, how bad was the damage. Anyone else have this problem. I called my dealer and he is coming out to inspect.

  53. Scott Bonneville

    My pellet boiler is located in a shed at the back of my garage. My dealer sent me a letter stating that if it is in a enclosed building that they will come out install a device that stops the back burn. By getting the pellets wet. I have contacted my dealer still waiting for reply

  54. Hey Tim,
    So sorry to hear the news. Central boiler gave me a replacement boiler, but I had to do all the removal of the old boiler and hooking up of the replacement myself. My power outage was my own doing. I shut off power because I was going to be away and did not know I should have run the clean-out mode to clear the auger of pellets. There should have been a lot of warning in the owner’s manual about what happens if the boiler looses power. I have had auger issues with the replacement boiler and they have sent me a new auger and snap disk and again they expect me to cover the installation of these parts. You should ask for your replacement to be the latest updated models. They have made several changes.

  55. thyanks all for the info. it has been very helpful. bought a 250 this year and installed it in the fall. had a harnmon pellet stove in house that was very efficient and burned about 4 tons every year. house is modular with 9 ft. ceiling and a 24 by 28 great room eith a 18 ft. apex ceiling. what was i thinking? propane costs were out of sight and made me realize i had to do something different. found centrol boiler and after looking into it bought the boiler. i did the outside work myself and ran pipeing to house boiler. plumber did his job with a additional circ. pump and cryotec anti freeze in the lines. total cost was around $11,200. had some initial problems with the unit firing up. after discussions with dealer and home office realized that the thermocoupler was loose and would not fire. started water at 190 and lowered to 175 by end of
    season. will fine tune water temp and fan speed next season. went through 8 tons this year (dec. to mid march). used the stove in nov. and part of oct. rough calculations find that i saved betewwn $1800 and $2000 this year what was about what i had estimated. pay back in about 5 years BUT a much warmer and evenly heated house. around 68 degrees. clean up took about 4 hours and the only problem i had was ther removal of the agiatator. after taping counterclockwise and a little wd-40 it slid off. thanks paul on all the info especially on the gasket. talk to you all next year.

  56. Thanks all for the info. It has been very helpful.Bought a 250 this year and installed it in the fall. Had a harnmon pellet stove in house that was very efficient and burned about 4 tons every year. House is modular with 9 ft. ceiling and a 24 by 28 great room With a 18 ft. apex ceiling. What was I thinking? Propane costs were out of sight and made me realize I had to do something different.Found centrol boiler and after looking into it bought the boiler. i did the outside work myself and ran pipeing to house boiler. Plumber did his job with a additional circ. pump and cryotec anti freeze in the lines. Total cost was around $11,200. Had some initial problems with the unit firing up. After discussions with dealer and home office realized that the thermocoupler was loose and would not fire. Started water at 190 and lowered to 175 by end of
    season. Will fine tune water temp and fan speed next season. Went through 8 tons this year (dec. to mid march). Used the stove in nov. and part of oct. Rough calculations find that i saved betewwn $1800 and $2000 this year what was about what i had estimated. Pay back in about 5 years BUT a much warmer and evenly heated house, around 68 degrees. Clean up took about 4 hours and the only problem I had was the removal of the agiatator. After taping counterclockwise and a little wd-40 it slid off. Thanks Paul on all the info especially on the gasket. Talk to you all next year.

  57. James Timmerman

    A lot of good info. there, with the temp. warming in
    mid march (central WI.) I still was going thru about
    one 40# bag of premium hardwood pellets a day. So I decided to try a little experiment with a timer on the recirulation pump, so i found one that you can cycle every 15 min. And right now I have the settings @ 9am-7pm it’s set for on a 1/2 Hr. and off a 1/2Hr. And 7pm- 9am it’s set for on 3/4Hr. and off 1/4Hr. and it seems to be saving me about 25 percent of the usage. Of course I wouldn’t use the timer in the middle of winter, because mine doesn’t have glycol in it because of efficiency reasons. And by the way I just installed it (M250) last fall in Sept.

  58. I was just curious, how does the addition of glycol lower efficiency??? or not? How else can you keep the unit from freezing in the event of a power outage or winter vacation????
    I have a CB pellet feeder that i retrofitted to fit my old wood stove. Same set up as the Maxim. I love this baby and I am burning ground up wood chips I get for free from a local tree cutter. I bought an old grinder/mixer to grind up the chips in a pellet size that will not clog the auger. Shazzam! Free Fuel! I have also burned oak saw dust that I dried out on my garage floor with a box fan. The saw dust burns a little cooler than pellets, but it works fine. If all goes well with this CB feed system, I am buying a MAXIM soon to heat my house, guest house, garage, office, and my 33′ pool and hot water in summer. Why would anyone want to burn cordwood anymore????

  59. So glad I found this post. I have an old Central Boiler wood furnace and have been thinking about upgrading to the pellet burner. No complaints on the old wood boiler, but thinking as I get older the pellet burner might be easier to deal with.

    Thanks for the great post and all the comments/feedback!

  60. Anyone put a Maxium inside agarage attached to house?

  61. Mine is in the back of my garage. in a shed. They say you cannot put it in a attached garage

  62. Having trouble with a M250. I purchased the unit in September 2010 and have had a couple of problems with the unit. The biggest issue is smoke in the hopper. The effect of the smoke is that it deposits particles/creosote on the pellets which makes them stick together and they won’t feed into the auger. I have to stir the hopper and add pellets every morning before work and every evening after work. I’ve had a couple of instances where it wouldn’t last through the night and the fire went out for lack of pellets. This has occurred with the factory settings and a host of other settings. I talked with dealer and he feels that the fire may be back burning in the auger system and the smoke is being sucked up into the auger system and suggested I slow down the fan speed and bump up the feed. As of right now the settings for the fan are: Low – 1 green, Medium – 2 green, High – 1 green. The feed settings are: Low – 1 yellow, Medium – 2 yellow, High – 1 yellow. I think I’m burning more pellets with these settings and I’m still getting smoke in the hopper to the point where it is impeding the pellet flow. The chimney is not obstructed and I’ve been faithful at cleaning the unit every week.

    Second issue. The auto relight does not work properly. The dealer is coming out this Wednesday to look at both issues. He thinks the auto relight may be linked to a problem with the gas regulator. To me it seems more like the ignition system is faulty. In any case, the system will try to relight but only “huffs” a flame but will not sustain a flame. When I clean the stove each week, I have to relight with a torch.

    Any insight for trouble shooting would be appreciated.

  63. Kevin
    I hope the community reply – after your technician has bene by could you please post here his views – many thanks Rob

  64. Kevin,
    To reduce or eliminate smoke in the hopper you should always made sure your hopper is fairly full; if the hopper is almost empty all the time it will allow too much air to enter the auger system and allow smoke to make its way up into the hopper. Try these settings: feed: low- two green, Med- one yellow
    High- one yellow – Air: Low-two green, Med – 1 yellow, High- 1 yellow. Make sure you run clean out mode once every day or two. You may also want to try a different brand of pellets or even better, mix corn with the pellets; 80% corn 20% wood pellets.
    Everyday make sure you stir the ashes in the burn pot to make sure ash chunks etc, are not impeding pellets from entering the burn pot. Your lighting problem is probably your regulator or ash is blocking the end of the igniter.

  65. Just a quick note on the aerator… the replacement aerator (made I believe out of stainless) seems to be a great improvement. I have burned about eight tons with it and absolutely no sign of deterioration.

  66. Thank you for the input. I had the Dealer out this evening and he talked with Central Boiler via cell phone while we were troubleshooting.

    As for the smoke in the hopper, Central suggested adding another section of chimney pipe to create a better draft. We put on another 4 feet making the chimney a total of 12 feet. Central also suggested some settings for the feed and air. They are as follows – Feed: High 2 yellow, Medium 2 yellow, Low 1 yellow. Air: High 1 yellow, Medium 1 yellow, Low 1 red. The person we were talking to has a M250 and these are the settings he uses on his personal stove. I will monitor the performance over the next couple of days to see if these changes help.

    We also looked at the auto ignition problem and determined that the igniter is OK. It appears to be a problem with the gas system. As Paul suggested it may be the regulator. I will need to have someone check it with the proper equipment to determine if it is faulty.

    I will post again when I have more information.

  67. Thanks for the update. i have a 175 When i get smoke back into the hopper it means it is time to claen the exhaust tubes. I clean them and smoke is gone.

  68. Thanks guys for being so helpful

  69. Currently we have a wood/oil burner Viessman unit that is getting near the end of its use. As we are getting older, we are tired of burning wood–it is messy and because of my pacemaker, I am not suppose to run a chain-saw. We both work so are not here during the day to stoke a fire. I have to seriously consider another source of heating. I have been investigating the Maxim corn furnace (outside) and would like some suggestions. We are in southern Ontario near Drayton,Ontario in an old stone house (newer windows, doors,etc.) We live close to feed mills so access to dried bulk corn is not a problem. Suggestions.

  70. Sounds like a good choice for you. Have you checked out the web-site

  71. was just out by my maxim 175. it sounded like the augers were really working. I noticed the water temp was bown to 160. I have it set at 175. Does anybody every run the hoppers out of pellets on a regular bases. I have noticed some pellets fines but the stove has been running fine. I have put 130 bags thru the stove this year with no problems. I have cleaned out the hopper and can see the top auger . sometimes it turns fine the it get boggged down. How far does the auger turn in a cycle?I beleive the burn auger is turning about a 1/4 turn everytime. The company came out in the spring and added a saftety feature to stop burn back.

  72. Scott,
    Make sure the four bolts holding the auger to the fram in the back of the unit are tight. I was getting incomplete burns eariler in the year and upon examination found two of the bolts fell out and the other two were lose making the auger flop around when feeding pellets. I was lucky I didn”t get a burn back.

  73. people this is a mechanical device and in the big picture a new one at that . it needs service . every year I go through every nut bolt if I find one loose I take it off and apply green locktite then reinstall so it will not loosen up again . I clean the unit from top to bottom inside and out and put it to rest for the summer months . this should be done every time it goes into rest . as for all the little problems people are having common sense needs to be applied here . of course when unplugged, shut off or power outage the pellets will smolder and if there is fresh fuel near by the fire or embers will travel to that fuel. that is common sense . ( when we had our big power outage 3 years ago all I had to do was go to the boiler (and with the long bent rod that comes with the unit ) scrape the burning embers away from the back of the burn pot and all was fine . too much smoke ? your feed rate is too high for given heat call . not enough heat feed rate is too low . when your unit is running ( calling for heat with water temp below desired setting ) the fire should be bright yellow to red like the sun not white and the fire should engulf the burn pot . NOW pellet quality does play a part in all this try to burn crappy pellets and this unit will give you nothing but problems I burn energex premium pellets nothing fancy and they are soft wood pellets at that and haven’t had a problem once I got my settings sorted out I have No creosote , No caking and No smoke all I have is a fine powder like ash . I don’t have to clean it all that often and have only had to empty the ash hopper 6 times this winter and cleaned it 3 times I am running the 2 sections of a vent that came with the unit and one section of 6 foot stainless b vent on top for height with a non restrictive cap . nothing fancy . I get no smoke ,no build up and no back burn / smoke in pellet hopper . lastly remember this unit runs on the premise of air flow and hot air flow at that keeping the exhaust hot will increase flow as it travels up and out the stack . you want more out than is being put back into the unit . simple and my unit is one of the early 175s I think it is a series 2 I ran 6 tons this year of which I have a little over half a ton left and plan to run it out then convert back to oil for the summer . 2300 sq ft home 2 zones running through a tankless boiler forced hot water and running it non vented / sealed . with no pressure hope this helps . again do not over think it

    • Thanks mike . I think the problem i was having was in the pellets. They are Maine pellets. I had them left over from last year. They had a lot of fines in them. After i ran them through a vacuum system to get rid of fines . No jambs on the auger. As for smoke in hopper. . It usally happens right before i clean it the exhaust tubes. I soon as i clean them the smoke disappears. These maine pellets have a lot of ash. I have a 1400 square foot home two zones and a detached garage 1000 feet also heated. used 7 ton. Roughly have to empty ash 1 a week.

      Thanks Scott

  74. We purchased the Maxim M250 in November 2009. Every 6 months the auger has to be replaced. The dealer agrees that this unit is a lemon and yet he will do nothing to make it right with us. Three of his employees have stated that they need to stop selling this unit as there is always something breaking down. When we first purchased the unit, the dealer said that the others he sold them to were very happy. Now his story has changed. The dealer now claims that he didn’t want to sell the unit to us and really tried to warn us, but since we insisted, he sold it to us (the guy has problems with lying). He has refused to give us the names and addresses of the other “happy” customers. He has already stated to us that he will never sell another M250 again. In the meantime, we have learned that there was upgrade on the cast iron aerator changed to a stainless steel one over a year ago. We were never notified by the manufacturer or the dealer. Now damaged has been done because of the broken aerator. The dealer is NOT offering to pay for anything. The dealer has been negligent before when problems arose. I can call his office with a problem and things appear to be getting handled, but come to find out, several months later, this is all “news to him.” So we have spent $8000 on this unit that we can’t get very much warranty coverage and a dealer that doesn’t care to inform us on upgrades, and we are broke.

    Anyone want to buy it? It’s cheap! We won’t be using it again, won’t run! Don’t worry about the manual, I will supply that. However, you have to be really good at reading between the lines since it is so vague!!!

    If you are looking for a unit that is dependable and the manufacturer is willing to stand behind its product and not bail out, buy a Nature’s Comfort. That’s what we ended up purchasing. We can’t deal with the dealer for Central Boiler. Neither one of them care about the customer.

  75. Ann,
    your problem lies in the dealer not the manufacture . contact central boiler direct and voice your concerns they will set it right . I dealt with them once and they cursed out the dealer and sent me what I needed directly and apologized numerous times … I have heard the 250 kicks ass .. although I haven’t seen one in use or been to mess with it I have heard they are better than the 180

  76. The LED read-out on my Maxim 250 just started to fail. A few of the segments do not light up, so you see only parts of numbers. Has anyone else had this happen on a two or three year old unit? My dealer is looking into the problem…

  77. Having issues upon starting my M175 up for the heating season in NH. It apparently keeps backburning on me, and activating the “fire hose” back burn protection into the drop zone between the upper and lower augers. This has happened 5 times in the past week, 3 of those in the past 36 hours. It had never happened until the very end of last heating season.

    The problem becomes that when this happens, it drains water off the tank through a hose and into the drop zone area, to put out the apparent back burn. After this occurs, the pellets in the drop zone solidify into a cement like mass. This blocks the pellets, so that they can no longer feed.

    I’ve called our salesperson where we bought the furnace several times. He thinks its because my feed rates were too high for the “warm” weather, and had me change them. Problem is, most of these problems have occured overnight when its been from 25*F to 40*F, and I’ve been using this furnace for 3 years, sometimes with air temps over 60*, with no problems.

    Like many, in the past I’ve had some smoke issues in the hopper, usually when it needs cleaning, and once or twice I had some smoldering pellets in the upper auger area and some carmelization of pellets in the hopper. Again, these usually were because I needed to do a good cleaning of the tubes and chimney. These issues never activated the water drenching system in the auger drop zone though, so I could always just feed the auger and clean/reload pellets and keep going.

    So, now my contact at the dealer is having me set feed rates down where I’ve never set them before, and I woke up again this morning to another “flame out,” Checked the water tube to the auger drop zone, and yet again it was wet from having soaked the pellets, apparently to protect from the back burn.

    My contact says when this happens you can open the pellet viewing window in the drop zone and use a bent coathanger to scrape the cement like stuff and clean it out. Doesn’t work, because water flows DOWN, and the cement pellet mass extends down into the lower auger area, where you can’t even scrape with a long bent screwdriver. So every time this happens I have to remove the entire upper auger unit in order to access the lower auger feed area. The whole process takes about an hour.

    Obviously I can’t keep ripping apart my auger assemblies every day all winter long. I don’t have an extra hour every day, AND I while it’s 45* this morning, I really don’t want to be tearing the furnace apart for an hour in -20* weather in January.

    Any thoughts on why my furnace, after running fairly well for 3 full heating seasons (going into our 4th) is suddenly deciding it has to back burn every time it apparently idles down?

    James Pushee
    Hillsborough, NH

  78. I have found that exactly the opposite strategy helped keep the Maxim from back burning at long periods of idle. I had to up my idle feed rate to keep the pellets advancing a little faster to counter the tendency to back-burn. Basically the tendency to back-burn at idle is because of the slow advance of the pellets (the worst is when the auger stops altogether under a power failure).

  79. Where is the sensor or thermostat that regulates the backburn protection?? I’m wondering if that might be faulty, and causing the unit to decide it is backburning when it really is not?? On yesterday’s incident, when I looked in, the “charred” pellets only went about an inch or two into the auger area, and behind that was a gap and then the cement mass of soaked pellets.

    Or, is this telling me that the upper auger is not working right (running too much), and dropping too many pellets down, not leaving a gap and creating a backburn, which once stopped by the water line and plugging the upper auger, is allowing the lower auger to push the charred stuff back into the burn chamber?

    Does anyone know if Central Boiler would have people that would answer questions like this, and how to get a hold of them, as the dealer is useless when he does call me back, which isn’t very often. I haven’t tried recently, but several years ago recall having trouble finding CB’s numbers or getting them to answer questions without just getting a corporate message back to see my dealer.

  80. Update on back burning problem- today came home after being away for 4-5 hours. Pretty warm today, so it probably wasn’t running much with the house empty and air temps in the 50-60* range. The furnace had “flamed out” but still obviously had pellets in the auger and some had been fed and not completely burnt in the burn chamber.

    Is this signaling that perhaps the ignition system is actually what’s acting up, and not relighting after a period of idle, thus allowing the back burn of pellets to smolder into the auger area??

    The ignition system seems to work fine when I out looking at it, usually when I’ve just cleaned it out, which means I had to power it down to turn it back on and restart it completely. Just put a fresh propane tank on it this morning, so I know its got gas for the starter.

    Short of sitting out there and checking it literally all day to see how it “relights” when it has gone out on its own, how would I check to see if the ignition system is working properly on its own?

    Still have the question about where and how to check function of the back burn protection sensors?

  81. James – I suggest you contact some of the folks who comment here on the site – they are the ones who know a lot – Yours Rob

  82. i was told HP plumbing in springfield Vt has tech that is good with central boilers. there number is 802-885-2300.

  83. Vickie A~
    I am having an issue with my Maxim 250 boiler that I bought in 2006. I have only had a few issues in the past, including the smoke, tar, auger, and pellet consumption issues everyone else is having. This morning when I woke up I noticed the water temperature had dropped to 141, the fire was still burning strong. The water flowing through the pipes was only luke warm to the touch. I thought it was the water pump, but after purchasing a new one discovered this was not the issue. The dealer has yet to return my call,as he never does, and Central Boiler thougth that it was possible the pipes had frozen. I have been trying to defrost them all day with heat and still having no luck. The water temp has risen but it is still not properly functioning and kicking out the heat it normally does.
    Has anyone had issues like this before or have any suggestions? I did not mention that I live in Alaska and we dropped to -40 over the past few days, but I have never had this problem before.

    • After spending 4 hours last night trying to defrost the pumps, I still had no luck. The water is still getting hot but not flowing through the pipes. We used bopiling water with towels and a heat gun warming the entire pipe. The intake and out take pipes connected directly to the water source are the only ones that are warm!

  84. Vickie,
    New M250 installed this month, same issue; Boiler 185; water at Heat exchanger inside the house 165 at best. I’ve messed with the settings without much success. Going back to greens on high & med and only 1 red on low.

  85. By the way I’m in North Pole.

  86. After several days attempting to defrost the pipes with heat tape, boiling water and a heat gun we decided to replace the pipes. When we took them off they were frozen and had ice in them still. We are also in North Pole. Again, this has never happened in years past even with these temps, sounds like everyone here is having issues! We kicked the stove back on and the temp went up to 204!!

  87. We have a Maxim pellet burner and I would NEVER suggest it to anyone!!!!! A “friend” of ours “gave” us one after he had it for a year, claiming he had access to a large supply of wood so was changing to the wood fired furnace. Naively, we accepted it and spent a LOT of money having it brought and installed in our Northern Minnesota home. After four years of almost constant non-use because the auger kept breaking, we finally got hold of a FORMER dealer and he sent a new stainless steel auger to replace the pot metal one (the third one of those!!!) So now we thought we were back in business. HA!! We spend more time cleaning the thing out, filling it with pellets, and cussing it out than we do enjoying our very recent retirement! As soon as we have used up the $2000 of pellets we have (hopefully, they will last more than a couple of weeks!!), we are going back to our propane furnace!

    pellets we have stored in a newly built room off our garage for the damn things, we are going back to our ropane furnace for good!!

  88. Well, now that I have calmed down (don’t blog at 1AM!) and read the very interesting and helpful info from several of the guys here, I went out at 2AM that morning and reset the settings on my 175. Voila!! It works much better and I am now hoping we have solved the problems!! Question: We have the system hooked up to our water heater. Is 175 degree water too hot for PVC pipes? And for the dishwasher? Do we need to add a mixing valve to the hot water line? I am not using my dishwasher because I think the water is too hot. Would love to get some feedback on this . Thanks!!

  89. Sue,
    I run mine at 170 and without a mixing value. I have found that running it much higher just wastes fuel. This temp seems fine for my dishwasher. If you have a long run from your unit to your house you may need to run it at 175; my unit is about 30ft from the house.

  90. Thanks, Paul! My unit is in my garage and is about 70 to 80 feet from the house. What do you think? Should I turn it down those 5 degrees? Anything that will help save fuel sounds good to me! My dishwasher doesn’t have the stainless steel interior. Does yours? If not, I will take your advice and use it again! Yay!!

  91. Now I have another problem!! The end of my brush pulled off inside the lower left exhaust (?) tube! I opened the back of the box at the bottom of the chimney to see if I could grab it that way, but that twisty piece of metal that is inside the tube is stuck too because of the brush end. Do those things come out? THe furnace is tii close to the wall by about 6″to foot which I think will have to be remedied in the spring. I think I can pull it out if I pull up on it, but don’t want to wreck the thing. What are those called anyway and what are they for? My guy that I had install the Maxim for me and who knew (or thought he did) about the furnace passed away last summer so I am now trying to learn everything I can so I can keep it running properly. Hubby has never been the one to take care of this kind of thing! I have become a Jill-of-all-trades and am hoping this is the last thing I have to learn about so I can kind of retire too!!

  92. Scott Bonneville

    Hello suu i know what you are talking about. Those tubes are to help the exhaust gases leave the burn area . it makes the exhaust spin. easier going out chimney. Those peicses just slide out the back of the unit. you take those out before running the brush thru. You should be able to pull the twisty thing out.. Some people wait till there stove is out of pellets and shut down to clean the tubes. I have never done this. I wait till my stove is in idle mode then i clean it. I can do it all in about a 1/2 hour. The better quality pellet you have the less have to claen. I know from experiance. I had cheap pellets alot of had to clean about every 5 days ash would build up in tybes and ash champer. Got better pellets this year. Hope this helps you out .

    Scott B

  93. Scott, Thanks a lot!! The more info that I get, the better I like it! I really appreciate the info I’ve been getting and am so gald we are getting good use out of the furnace! Thanks to everyone!

  94. To anyone that has a Maxim 175.
    Had problems since day 1( Nov of 2006) received update kit did okay after that .Always used corn pelets mixed, went down last year in December, dealer said it was transformer put new one on still wouldn’t lite, dealer said must be spark inition, put new one on,still nothing.Come to find out was the combustion fan after , was so cold in January 2010 didn’t put it in until this October, ( burned Lp last year then) Stared up after fan was installed,but now it starts up but the gas won’t shut off unless it goes to FO mode(fire out). I restart does the same thing until I restart it 3 times and the water gets to the 165 degree then it will burn for a while when it calls for relight it goes back to the FO mode. Then redo what I have been doing,Can’t get an answer from central boiler people or the dealer. I’m thinking it must be in the firestar controls. I did go to all pellets this year and set the modes like I have read on your forum they are burning great. Very tired going out to relight I hope someone will let me know what they might think.

    • shut your furnace down ( turn off power at furnace with power button on furnace ) disconnect propane . push power button let it do its thing for a couple minutes maybe a 1/2 hr . turn it off . reconnect propane and restart with auto relight off . let sit for a while and then turn auto restart back on …

  95. After the unit is up and running can ypou just diconnect the propane. My stove stays running all the time. just idles down the fires up when temp call for it.

  96. It is fine to disconnect the gas once running, but you might benefit from keeping it connected and the ‘auto relight’ activated on the chance that you lost the fire for any reason (except out of pellets or corn) at an inconvenient time.

  97. Scott Bonneville

    Hello tom, I tried resetting my new email address but, i quess it didn’t take . My new email is :

    Thanks Scott

  98. Just bought a new maxim 250 and had it installed the last Friday of December. Heated up my house great on start-up, but I was incredibly disappointed in the owner’s manual. I’m not by any means mechanically-minded, but I’m not a total idiot, either. I haven’t been a wood-burner before–have had baseboard system fired by fuel-oil boiler and didn’t want to keep paying sky-high oil prices.The manual doesn’t even give decent instructions on how to clean the ash out. Should the power be shut down to do that? Same for the chimney transition–should it be powered off before doing that? I read the manual pretty thoroughly and it is useless on what to do for routine maintenance. After reading through it, I was a little worried about the possibility of a power outage (gave 1 1/2-pages of instructions on pulling out the guts and reassembling it in case the thermal valve discharged, so wasn’t too thrilled to think about that.) As luck would have it, the power DID go out two weeks after i had it installed. I thought it was firing up OK after the power resumed (after six hours), but then checked a second time and it was flashing “FO-fuel out”, so called the dealer. If I have to spend a couple hundred dollars or more every time the power goes out, I’m pretty sure this isn’t going to save me any money over the high oil bills. Then, this morning, when I checked the hopper to see if I needed to fill it, I noticed that some of the pellets around the rod or post (which runs up through the entire furnace and has the acorn nut on top) were wet–it was raining heavy this morning, so water must have seeped in around the post and but, even though there’s a gasket on it–yet another disappointment in the design of this furnace. The one good thing that came from the power outage was that I was at least able to clean the ash-box without burning my arm, but I’m still not positive on how this should be done when it’s running. Can anyone give me a step-by-step on what they do to clean out the ash-box? (and the chimney transition?) thanks!

  99. DEB,
    First thing is to get a old jacket that you might be throwing out. Either power down the unit or wait for a warm day when unit is on standby. Get a flat feed scoup that has square corners, open the door and let any smoke or ash settle down. I put the scoup in and slide it along the bottom into the corners. Lift up slowly and empty into a metal container. Repeat this process until all ash is removed. Dispose of when cooled down. At this time you can also check the auger for any problems. When finished power up the unit. Take the jacket off, turn it in inside out and leave it on the porch where it can’t get wet for later use. Clean it in the spring after final cleanup.

  100. Gee, Tom,
    Thanks for the advice on the old coat. Too bad I didn’t read your post before I ruined three of my Sunday best dresses!

  101. We are highly considering purchasing a 250 unit to replace an Amaizablaze unit we’ve had in our basement for the past 7 years and finally died (i.e. erroded beyond repair)…we have read through the posts (great info btw) and know from our prev unit that its alot of trial and error and many variables play a part in how it works. What we are MOST INTERESTED in knowing is how far people are placing these units away from their homes? The company stated that the unit can properly maintain water temps for up to 500 feet away and the dealer stated 300 feet. Obvioulsy the farther away the unit from the house/bldg you are heating, the more the temp drops. The dealer indicated 1 degree for every 100 ft away from unit. We’ve seen many a outdoor wood unit that is in the middle of people’s yards and it just looks goofy. The spot we are looking at is approx 100 feet away from the furnace but we’re also hoping to heat a polebarn in the winter and pool in the summer. Any info on location of units/how well they are working from those distances would be great! Also….are most people putting these units in a building or just setting outside. With maintenance/cleaning, standing out in the middle of a 10 degree day doesn’t sound appealing!

    • Hello wendy i have a 175 model. it is locates on the back of my garage. I have a 85 foot run to the house adn about a 10 foot run to the garage. It is in a inclosed room. i have no insulation in there. But as was stated before under cover is a good place. It nice to be out of the weather filling and cleaning.I clean my stove about every ton. More if i have bad pellets. That is the key get good pellets. With my stove at 85 feet away i have no loss in temp.


  102. I have my 250 in a shed which is very near the house so I can’t address the heat loss question.. however I do recommend a roof over the unit for bad weather maintenance and filling etc.. and a light and spare outlet too. Enough space to store pellets is also great. If you plan to use bagged pellets rather than any type of bulk silo it is great on those cold winter days to have the pellets under cover and right near by. I just installed the new battery back up unit that protects against back burning when the power is out. Great devise!! I was one of the ones that lost my whole boiler to back burn a few years ago. This devise was what I imagined would solve the problem, but they came out first with the water fed protection that soaks down the drop zone and lower auger. That never seemed like a reasonable solution… major headache to clean out after an episode. The battery unit ties into the wiring and basically powers just the built in back burn protection during a power outage. Under normal powered conditions the built in back burn protection should always work before the water extinguisher system kicks in. The snap disk sensor that basically runs the clean out mode if it senses too much heat (back burn) in the auger area comes before the one installed to activate the water. If any one is having problems with the water extinguisher kicking in under normal powered operation then there is a problem with how the sensor for the extinguisher was installed or the sensor for the built in back burn sequence is defective.

  103. Just installed a new M250 a couple weeks ago. So far, I’m quite pleased with it, although I’ve noticed that when I inspect the drop zone through the glass, it is filled with pellets. My understanding is that the drop zone should be clear to protect against burn-back in the event of a power outage. I suspect that this shouldn’t happen if the burn chamber auger and hopper auger speeds are set correctly (i.e., it would make sense if the burn chamber auger was set such that it draws pellets away at a quicker rate than the hopper chamber delivers them). I have no idea how to adjust the relative speeds of these two auger systems, so for now, all I’ve done is re-set the auger and fan settings to factory defaults. I’ll see if this helps, and will post a follow-up. In the meantime, I was wondering if anybody else has had a similar problem? Thanks.

  104. The following quote is from another forum. I used the info to adjust the augers in my 250 to minimize build up in the drop zone. I still do keep an eye on the drop zone. It is good to understand that the ‘clean out mode’ runs just the lower auger and is an easy way to clear the drop zone if deployed just long enough to do so.

    The quote…
    “To adjust your upper (hopper) auger run time, you hold down both of the high-range up-down buttons at the same time. When you do this, the middle range LEDs are now your upper-auger run time. Use the middle-range up/down buttons to adjust the upper auger run time….”

    The battery back up kit that Central Boiler has put together for the Maxim is $140 and easy enough to install if you carefully follow the instructions.. It covers just the back burn sequence during a power outage and runs the lower auger if a back burn is sensed.

  105. Thanks, Tony. Subsequent to leaving my post yesterday, I stumbled on the same web site and instructions on how to adjust the hopper auger speed relative to the firebox auger speed. Using those instructions that you quoted, I reduced the hopper auger speed one setting (from 4 green + 2 yellow lights to 4 green), and over the course of a few hours the drop zone slowly cleared out. So now I feel as though I can sleep at night without worrying what will happen if the power goes out. I am absolutely amazed that the factory default settings apparently have the hopper auger pushing pellets into the drop zone at a faster rate than the firebox auger can take them away. This really seems to be a recipe for disaster, and I suspect that a lot of people are operating their boilers in accordance with these default settings. I’ve been reading this blog for a while now, and I always wondered why so many people were concerned about burn-back – after all, it seemed to me that the boiler’s drop zone is designed specifically to create a gap in fuel supply so that burn-back can’t happen. Now I know. The factory default auger settings seem to be creating a situation where burn-back is almost inevitable in the event of a power outage or an auger jam! If anybody out there is operating their boiler with the drop zone filled with pellets, please read Tony’s note (above) and take your hopper auger speed down a notch. Pellets should drop through the drop zone (hence the name)! One thing to consider, however. After making this adjustment, it occurred to me that I had effectively reduced the rate at which the pellets enter the burn chamber (the hopper auger speed is now rate-determining), so I’ve decided to lower the blower settings for Medium and High modes by a notch to ensure optimal performance.

  106. I have a m175 that I used to heat approximately 1300 square feet. I had it tuned right in and it worked great. Now I have moved it to my new house which is 3300 square feet. The boiler dumps directly into my pressurized boiler in the basement (now depressurized). From there there is a zone for baseboard, my water heater, and then a mixing valve for my three radiant zones which I run at about 130 deg. I am having trouble getting the stove tuned in as far as fuel consumption. I think that I am burning too much (4-5 bags a day of ambient hardwood)

    Any suggestions on my feed rates. I can get the air rates once I have the feed rates.


    • Chad i have my 175 hooked up to my boiler. I didn’t want the two connected. so i have a heat exchanger. I heat my 1450 home and 975 garage. plus hot water. roughly a two bags a day.

  107. I own the Maxim 250 which I just purchased and it has been running for about a month. and the biggest issue I have had is Back Burn and I just cant seem to get the unit settings right. Does or has anybody else on here had BB issues? Luckily the BB is just going into clean out mode is which prevents any damage but it empties out the auger almost daily so this makes the unit a lot less efficient then it could be. I’m hoping somebody else had this issue and can help me with what could be wrong. When a call is placed to Central Boiler they refer me to my salesman which doesn’t know much of anything about the settings on this unit. I did notice yesterday my Boiler stays in the low setting for long periods of time(about an hour) and maybe this is why I’m getting backburn warnings. I would definitely like any feedback from anyone who maybe be able to help me with this issue.

    • Backburn happens during idle when the pellets are being advanced slowly to the fire box. I have found that with some pellets I have to use a faster idle feed rate. The faster feed with a lower air setting is not as efficient but does work for me to keep from BB.. Some brands of pellets tend to BB more than others, so if you change brands you may find that you can get away with a slower idle feed rate.

  108. So Tony what I’m getting from you is you have a faster feed rate on low and a low air setting? I brought my feed rate up yesterday in the low setting but kept my air setting pretty high so I think I’ll try bring the air setting down later today especially if I see that I had another BB when I get home from work today. Thanks for the reply.

  109. New the the Maxim 250 family and not impressed. Started off with transfer auger feed issues, pellets were building up under the feed auger door preventing it from closing. Cured that by slowing the transfer auger setting. Now my problem is I can’t seem to get the stove to stop running in medium mode. No matter where I put my auger feed setting or air setting is seems to hang around 168 to 170. My water temp is set at 175. I think I have an air issue because when I look at the fire in the burn pot is seems to be a fire rather than like a torching effect. If i take the cleaning rod and clean around where the aerator and the auger connect I get an increase in air flow and the get the torching effect, but as soon as it happens to go in low a few times if the outdoor temp rises it seems as though the pellets restrict the air flow again and the fire goes from a torch effect to a flame. My setting is 4 green on the feed and two yellow on the air. Also my burner temp when in medium seems to run about 750 to 810 and 1100 to 1200 in high mode. Not sure if these are normal burner temp. Stove is clean and i removed the burn pot the check for blockage and everything seems fine. Have even had my wife on the phone while I was at the stove to see if any of the zones were calling for heat and there is not much of a heat load. Just can’t seem to get the heat to climb. Tried calling my dealer over a week ago and he is still waiting for a reply from central boiler. I tried calling Central Boiler myself today and after an hour and a half of being on hold for service the secretary came on the line and told me there was nobody that could take my call (unbelievable). I am pretty disappointed with the customer service so far. Anyway any feed back on burner temps or any other advice would be greatly appreciated. On

  110. Anyone have a electrical wiring diagram for the Maxim 175

  111. Scott Bonneville

    Expericed back burn this fall. Now can’t get gas to re-light. Cleaned everything out.

    • Did the wire that powers the gas igniter come off or maybe it’s not plugged in all the way. This happened to me once!

      Sent from my iPhone


  112. Jeff where is this located? I didn’t know if having the back burn it caused another problem

    • It’s a good size wire like a grey color. I believe it’s at the top right corner looking from the back panel of the unit. If it came off it wouldn’t be from the back burn but the wire can just unplug from vibration or just not being plugged in all the way initially. If the wire is not in all the way the unit will not light.

      Sent from my iPhone


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