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:
feed:
low- two green
Med- one yellow
High- one yellow
Air:
Low-two green
Med – 1 yellow
High- 1 yellow

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.