Harmon p61 wont shut off.

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Patiobob

New Member
Nov 27, 2017
7
new jersey
I've been searching the internet to try and figure out why my harmon p61 wont shut off. I just purchased it used last week to replace a fairly cheap pellet stove I had attempted to use to heat my garage. I have a harmon p38 in my home and it is the best investment I've every made, so I sought out another one for the garage. This runs perfect and heats as expected, but I can't get it to shut down. Not being a newbie to the harmon or some of the esp issues it has I figured this was a simple search....Not so much! Here's what I've got. The p61 can have either a micro switch or a vacuum switch. I opened the cover and my stove has both! The micro switch and wires are in there, but not connected to anything, nor can I find anywhere it would plug into on motherboard. The vacuum switch is clearly connected and connected to motherboard. I don't know if motherboard was changed at some point and updated, or if it came this way from the factory and this unit was built mid an update. Since my issue is that it won't turn off, is it possible that the draft motor is set to high? I can only find info on vacuum switch if draft motor is set to low, but not what will happen if to high. When I turn the controls to off it just keeps running on a really slow "idle" mode. I came out to garage this morning and the thing was still running 8 hours later after it was "turned off". Motherboard, vacuum switch, or ESP sensor? I'm thinking no on the ESP...I've replaced many on my p38 over the years and they either work or they don't and the stove won't much of anything at all when they go bad. The controls all seem to work on this one.....except for off. Thanks in advance for any responses!
 
Is the ignition set to auto or is it on manual?If it's running in room temp mode with that switch on manual it won't shut down.But with the switch in the off position it should shut down.I'll do some research.
 
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Does the status light go out when you shut it off?If it stays on it could be a dirty potentiometer.You can clean it with some electrical contact spray.
 
If the exhaust blower does not shut down, then you need a new circuit board.
If the circuit board was updated there is no longer a connection for the micro switch. You can remove it and throw it away.
 
It is not an auto ignition stove. P61 not the p61a Manual light only, so no switch to set.
Is the ignition set to auto or is it on manual?If it's running in room temp mode with that switch on manual it won't shut down.But with the switch in the off position it should shut down.I'll do some research.
 
If the exhaust blower does not shut down, then you need a new circuit board.
If the circuit board was updated there is no longer a connection for the micro switch. You can remove it and throw it away.
I have to try and let it run out of pellets and see if blower shuts down or not. I was forced to unplug it other day to get it to shut off.
 
I don't know what a potentiometer is or where it is located. I'll look that one up and start there. Thanks!


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A bad pot can keep the stove from shutting down. A weak spot in the Harman and their answer to a few dollar replacement is to replace the entire board to the tune of around 250 bucks
 
OK lets make this simple.See the 3 knobs?Unplug stove,spray contact cleaner through the tiny holes the 3 knobs shafts are connected to,while turning them back and forth.And,hiya Bio.
 
You forgot to add a prayer. Like three of us trying to figure out the oil leak on my car, head mechanic thought rear main seal, I thought oil cooler and the winner was the guy with the wrench, pressure sender behind the intake manifold
The blasting with contact cleaner won't hurt and is readily available
Maybe wrong stove? He says it's a Harmon
 
It's the electronic thingamajig behind the dials on the stove panel.Sometimes they get gunked up.
Oh....that.....of course.......There are at least two of them on mine. Why didn't you just say thingamajig in the first place!? I've worked on hundreds of those.....They are usually connected to a "doo dad" and you can just follow the wires.....

I did look it up and will need to get some contact cleaner to try that. Thanks!
 
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Most auto parts stors carry crc contact cleaner. Check your local advanced auto
 
Does the status light go out when you shut it off?If it stays on it could be a dirty potentiometer.You can clean it with some electrical contact spray.
I got some electronic contact cleaner today. Cleaned it, and plugged in, with switch in off position, which I understand will do a hard reset. status light goes off when in off position, but stove is still slowly churning away. Stove is cold so it should be completely off when plugged in. Status light comes on when I turn knob in either direction for stove heat or room temp and augers/fans work as they should. Test position also works. I might try and pull the ESP out of my p38 in the house and see if it could possibly react different....Other than that, I'm stuck. I hate to throw a $260 board in it for what is my garage heat, but I may be forced to. I only paid $800 for it, so I could probably still break even on the stove if I had to sell it for some reason. I can't take board out of my p38 either, as even though the replacement board is listed as exactly the same, my p38 must be older as it has different wiring, board, and connectors inside of it altogether. I'd have to rewire everything to even test it.
 
Could see if you can get a set of pots and replace them if you're handy with a soldering iron or find someone that is. I have done three boards now
 
I would change pots first, but im a cheap sob. If the change didn’t help then a new board
 
Took a few minutes today to pull ESP out of my p38 and plugged it into the p61. It turned on when plugged in and then shut off completely. Turned stove to on...it turned on....turned stove to off...it turned off again. Problem probably solved! I'll order a new one and test stove out. I've changed around 10 or so ESP sensors on my p38 and the stove never reacted the way the p61 did. Learn something new every day! From what I can tell the esp on the p61 does nothing other than figure out if there is heat at the flue and allow the stove to shut off. On the p38, with slightly different controls, it is the actual sensor for everything and checks flue temperature to regulate pellet flow. If it does not work then the stove won't feed any pellets at all. Sometimes it even shorts out everything and the blowers won't even work. I think it depends on if it shorts open or closed circuit. I was assuming the ESP dealt with the stove temp to regulate the heat on the p61 also, and that is why it worked fine....I was totally wrong.
 
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Good deal!!:):)
 
The ESP works the same in all Harman stoves. Some stoves run different ones though but they basically serve the same purpose across the board.
 
OK lets make this simple.See the 3 knobs?Unplug stove,spray contact cleaner through the tiny holes the 3 knobs shafts are connected to,while turning them back and forth.And,hiya Bio.
FYI , this worked for me. our stove would not turn off until it was out of pellets even when we turned the dial to the off position. so, we lived with just putting in enough pellets for a couple hours.

I found this thread and removed the board, surprisingly easy, just a couple screws and I used some brake cleaner to spray the front and back of the "3 knob shafts". I used compressed air to clean up the board to get rid of the other stuff hanging around and put the board back in and it works great now, like new!

@Mt Bob - thank you!