Harman P-43 distribution blower works when in test mode, but...

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aronhk_md

Member
Mar 3, 2014
5
Bear, Delaware
Noticed something wrong on christmas day when the stove got really hot. I could smell it like I never had before. Noticed the distribution motor was not blowing. Had guests so shut it off. Days later I realized as I was cleaning everything that the exhaust T to the chimney was chock full of ash/soot. I emptied it, cleaned everything. The exhaust blower will come on and run fine in test mode. When shut off the fan on that motor spins easily and freely. But it does not come on at all in any other mode to run.

As an aside if I turn it on with auto igniter, constant burn and feed rate on 3 as I normally do......I'm waiting for the distribution fan to come on and it doesnt. So I turn the unit to off..............and the exhaust blower shuts off while there is a fire in the pot. Yikes.

Any advice?
 

aronhk_md

Member
Mar 3, 2014
5
Bear, Delaware
I'd say the ESP is dirty or damaged.

I did brush it off well. Could the ash blocking the exhaust cause the unit to overheat and damage that ESP? Like I said, the circulation blower runs well on TEST mode, and spins very easily . That blower blower light isnt even coming on during regular operation, and I was surprised that the exhaust fan just seems to turn off if I switch the unit to off after the fire is blazing in the pot.
 

SciGuy

Feeling the Heat
Aug 17, 2007
364
Constableville, NY
I did brush it off well. Could the ash blocking the exhaust cause the unit to overheat and damage that ESP? Like I said, the circulation blower runs well on TEST mode, and spins very easily . That blower blower light isnt even coming on during regular operation, and I was surprised that the exhaust fan just seems to turn off if I switch the unit to off after the fire is blazing in the pot.

IIRC the distribution blower will not be turned on until the control board via the ESP senses 155*F while the combustion motor will continue to run until the control board via the ESP senses ~ 90*F. Since both of these functions involve sensing with the ESP I hazard a guess that it may well be your problem.

Hugh
 

rickwai

Minister of Fire
Nov 1, 2011
1,313
ohio
ESP
 

aronhk_md

Member
Mar 3, 2014
5
Bear, Delaware
Thanks so much for the replies. I am going to try purchasing a new ESP then. Anyone here have experience with the $20 units from ebay vs direct from Harman?
 

SciGuy

Feeling the Heat
Aug 17, 2007
364
Constableville, NY
Thanks so much for the replies. I am going to try purchasing a new ESP then. Anyone here have experience with the $20 units from ebay vs direct from Harman?
Take this with a grain of salt, but the local Harman dealer has been quick to tell me horror stories about the inexpensive after market units frying the stove's control board. He obviously has a vested interest and it would seem to me that the ESP itself is a rather simple device that ought to pretty easy to reverse engineer. I look forward to other more informed replies.

Hugh
 

aronhk_md

Member
Mar 3, 2014
5
Bear, Delaware
I agree, it seems to be a pretty simple device. I would guess its not a "smart" sensor, but rather just has an open or closed circuit depending on temperature. Can't picture how it would fry anything...rather I would think a cheapie replacement might be more apt to fail or open/close at the wrong temp. But I'm no expert. lol
 

aronhk_md

Member
Mar 3, 2014
5
Bear, Delaware
This is a 2015 machine. It has the red wire one. Thanks everyone for the help. Ordered a red wire $20 piece on ebay. Guess we'll see how it works. I dont depend on the stove for main heat.