Maxim M250 not going into max mode

[pancura]

I have had the stainless auger now all summer. Wont know how well it works until I crank it this winter.

I am still running domestic hot water. Seems the system flashes all three bars when temp hits 190F. I cut back the high temp to 175 and lowered the minimum settings to half bars with air slightly less.

I still seem to get BB error. This worries me as this appears to me to be what would cause back burn. I have the water suppression kit installed but don't know if its kicked in when it goes into BB mode. I am not on site and my seperintendant is usually the one relaying the message so I dont see first hand what the system is doing. By the time I arrive its back to normal operation.

I think I will post a new thread on harnessing the power in the upper auger?

[jdeere5220]

Sounds like it can't run SLOW ENOUGH to just do your hot water. I'm not sure why you would want to do that really, isn't really inefficient to run the unit just for heating your DHW? I think the system works best if it's kicking out some pretty good BTUs on a pretty regular basis.
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Maxim M250 outdoor corn/pellet burner
Old Beat-up Gravity Box
I support Global Warming

[pancura]

I would have thought the unit would just go out if the demand is not high enough and I would have expected to see more propane usage to re-ignite the fire when a demand is present. Now I cut back my low rates but I still may have my medium rate too high. This may cause too much product to be feed into the burn chamber thus causing the BB warning. What do you think? This still does not make sense really. The only reason the system would be in medium mode if there is heat demand, so it should cut out 10F lower than the set point. Do we think its possible to add enough product during medium mode to raise the temp 10F and cause excessive back burner temperature?

I was 'luckily' on site last night to witness this event. The system was observed to be in BB mode with all lights flashing and the lower auger pushing the product away from the feed chute. I could not tell what temp the water was at as the controls were inoperable. I was a little concerned what to do? Should I shut the unit down or leave it run? I decided to open the door and brush the product down from the aerator into the ash chamber. A couple of moments later the system kicked into medium mode and started feeding product again. Just bizarre how this thing behaves! The set point temp is at 175F and at the time I think the water temp was at 162f. Anyway is the consensus the medium setting is set too high?

Keep in mind this unit heats 14,000 ft2 building servicing 18 families. I am trying to determine if it worth keeping going. In July I burned about 47 bags of wood pellets $235. I certainly do not want another back burn and toast my second furnace..... I expect to burn close to 60 ton of product this heating season. As mentioned I missed last heating season as my furnace had melted. I am quite concerned this could occur again.

Everyone's comments are appreciated. Thanks

[T_Hartigan]

235$ for 18 families with hot water doesn't sound to bad.
I think you need to understand if the snap switch on the lower auger is really getting hot or malfunctioning.
Decreasing Med may not help. If it really is back burn may need to increase idle.

A call to c.b. may be needed.
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3rd year with Central Boiler Maxim 175
100% corn first 2 years.
3rd year, Corn, Acorns, 1 ton wood pellets.

[jdeere5220]

[pancura]

I did not notice what state the furnace was in before we noticed it in BB mode. I have to assume it was in idle or low mode. The system was in clean out mode, so the bottom auger was running. The upper auger was not feeding the chamber. I did notice a large volume of pellets around the aerator. This is the product I moved into the ash chamber. After a moment or so after I cleaned the product from around the aerator, the system kicked into medium mode, fan kicked in and auger started feeding system with pellets again. Watched it for 15 minutes or so and it seemed to be working as expected again.

I will check the exhaust stack.

Agreed, I have to identify why this is occurring. I sent my distributor a note basically telling hime the same thing. If I dont get anywhere Ill have to call CB directly. In the past they have not responded to me directly only through my local rep.

Any suggestions on how to tell if the fire is spreading up the lower auger?

The other problem is I am not on site and it only occurs randomly. I cant tell when this will happen, or how often it is happening.

Thanks

[jdeere5220]

[T_Hartigan]

I've only run a few bags of pellets. I did notice that the fire would idle just at the beginning of the stirrer almost in the auger if it idled for long periods of time. I never saw a b.b. talarm though.

If you have a temp gun shoot the auger during normal operation by the snap switch and see how hot it is. Do the same if you are around during the alarm.

Maybe during these warm months it is running close to alarm or the snap switch is out of calibration.
_________________
3rd year with Central Boiler Maxim 175
100% corn first 2 years.
3rd year, Corn, Acorns, 1 ton wood pellets.