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johndough_gw

Too much draft incomplete combustion - stove goes out

johndough
18 years ago

I have a Harman advance pellet stove 3 months old. it worked excellent for the 1st 2 months then it started giving Status 6 codes most often a couple times a day- sometime a day or 2 would go by ok ( status 6 = Incomplete combustion)I did all the complete cleanings and everyting in the book a couple of times, had the service guy come and he replaced the esp probe and it seemed mostly ok for about a week ( 2 status 6's in that time-so problem not really solved) now they are back and getting more often, sometimes every 2 hours - service guy again cant find anything, but thinks its because I have a 4" vent pipe instead of a 3" (originally I was installing into a diffent spot that had a long run and needed the 4", but I changed after I recieved the pipe to a total run of about 4 feet) - anyway, he thinks the extra inch is causing too much draft and needs to be changed to 3". does this make sense? the draft meter he puts on it pegs out to max setting, and he said it should be about 25-35, after manually blocking the vent pipe the only way the meter reads within specs is to leave a very small opening of about 1 sq inch ( too me that says even a 3" pipe woould be way too much if thats the cause)

some other observations I've made are

this only seems to happen when burning at a low burn to keep room at constant temp

when restarting after a problem ( and room temp is 8-10 degrees below therm setting), the burn is extremely low about 1" max above the pellets for sometimes a half hour before going full- normal start a good 10" flame happens immediately

hopper often fills with smoke during the low burn time

there is NO wind outside - during the 2 months of excellent operation it was often very windy out for hours on end

after the 1st service/probe replacement flame never went full for long ( maybe 40sec at a time here and there), stove never shut off due to bringing room to temp, as it did previously, for the entire week ( actually it never got the room to temp since the heat output was minimal)

I am still using the same lot of pellets but I have tried a couple bags of 4 other brands just in case

SO..what could be causing this problem? I dont think its the pipe since it ran great for 2 months

Any suggestions greatly appreciated

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