I have an older P38 with 2 knob control style board. The stove runs perfectly well other than the stove not turning off (combustion fan). If I unplug the stove, and plug it back in when ready to light it again, the stove is problem free as far as operating it. The controls will increase and decrease the feed rate, and it responds to input as it should. The ESP probe is not the problem, as I bought and installed a new one, and it changed nothing. So I put the old one back in and repackaged the new one for now. My initial thought was the board was taking false readings from the ESP, say 150 degrees, so that is why the stove was coming on when plugged in, and not shutting off. But the new ESP has disqualified that possibility. Any ideas? Bad control board? Bob
Harman P38 combustion fan starts when plugged in, will not shut off
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heat seeker
Minister of Fire
Bioburner
Moderator
Turned my pc45 off this afternoon as we are starting the January thaw and the fan was still running 5 hours latter. Some have had theirs run longer. How long have you waited?
I have let it run out of pellets and let it run several hours long after any embers were present. The fact that the stove will run in the off position when immediately when I plug it in, tells me this is not a wait for the stove to cool issue.
Shorted Triac? Is that something that I can have easily repaired using the same board? Replacing the board is $300. I remember when these same boards used to be $70
Bioburner
Moderator
heat seeker
Minister of Fire
A triac typically costs just a few dollars, and is soldered onto the board. You need to find which triac it is, and verify that it's bad. There is typically an opto-isolator associated with each triac, which could also be bad. My industrial experience is that the higher stressed component fails first - that is, the triac.
There could be other causes, but from here it looks like a shorted triac. If you're positive the control board isn't calling for the motor to run, I'd say that's where I'd start looking.
There could be other causes, but from here it looks like a shorted triac. If you're positive the control board isn't calling for the motor to run, I'd say that's where I'd start looking.
Bioburner
Moderator
Here's another possibility, the pot switch could be worn and is a known issue of Harman stoves. Had a stove that would come on all by itself even after it shut down. About five bucks.
Welcome to the forum Bob.
Do you have a Harman dealer near you who can test your control board, or put it in their floor model stove to see if it reproduces your problem ? Or someone you know that has a Harman model that you can swap it into? As always, unplug before you do any control board removal !
Good luck, and post back on here with what happens for you.
Do you have a Harman dealer near you who can test your control board, or put it in their floor model stove to see if it reproduces your problem ? Or someone you know that has a Harman model that you can swap it into? As always, unplug before you do any control board removal !
Good luck, and post back on here with what happens for you.
jzm2cc
Minister of Fire
I've seen the same issue with my PC-45. Manual states it can stay on for up to 5 hours after shutdown. Talk about a waste of heated indoor air being blown outside if no OAK being used.
If you can detect a speed change in exhaust blower with potentiometer adjustment then I doubt its a shorted triac. In my case i noticed a difference in run times between two control boards swapped on the same stove.
F4jock
Minister of Fire
Agree.
If all else is OK why not live with it until the heating season is over and then.have the board repaired? Plenty of options, even on eBay.
Bioburner
Moderator
Well,
I know what the pentatometers look like, and can switch those out with a little effort and a soldering iron and vac, but I have no idea on what a triac looks like? Anyone care to describe what that looks like on these control boards?
I know what the pentatometers look like, and can switch those out with a little effort and a soldering iron and vac, but I have no idea on what a triac looks like? Anyone care to describe what that looks like on these control boards?
heat seeker
Minister of Fire
Another costly option is to buy a new board and swap them out and send the other off for the repair. Not sure what it costs but I thought it was $45 with the E-Bay deal. Then you have a back up at all times and from there on out it's a cheaper fix for the repair and your stove still runs at all times pretty much other than the swap outs.
Might not be the BEST option money wise but it is another option with the $200 +/- spare tire.
Might not be the BEST option money wise but it is another option with the $200 +/- spare tire.
Bioburner
Moderator
Boards are not available for the old P38. One can upgrade but that kit is around $275plus install.
Bioburner
Moderator
OP has heat, just the exhaust fan won't shut down which is more of an inconvenience than anything and sure could live with the issue till end of season. I have a lawn mower with the same issue and have to cut the fuel to kill it. Newer boards have dip switches that allow for either red or black ESP with a flip of the switch but I am not sure with the upgrade kit and would have more control over stove too. Have to search for someone who has done it here to be sure or go to parts supplier and look up.. CAn't remember all the stove details.
Sounds like an instance where manual igniter (if the 38 has it) would come into play to keep unit warm so it would not suck warm air from inside if outside temps rise. Really no worries if you are running hot I would think. Is the 38 a manual ignite stove? I can look them up and I know they are an older unit.
Guess the OP is in the better of a bad situation. At least the stove and exhaust blower is still working so they can still heat. Better than it being dead and unable to use it at all.
Guess the OP is in the better of a bad situation. At least the stove and exhaust blower is still working so they can still heat. Better than it being dead and unable to use it at all.
Bioburner
Moderator
F4jock
Minister of Fire
Bioburner
Moderator
LIKE! Planning on some thorough cleaning around here tomorrow. 51* Time to break out the sun screen!
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