Scary Event With Harmon P61a

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Sawduster

New Member
Nov 4, 2008
125
Vermont
I am a newbie pellet stove owner. I put down a hefty deposit on a Harmon P68 in early June and went through the same thing that everyone else did waiting months for a stove to become available. Finally received a call that I could have a P61a in "honey brown color" for the same price as the P68 so I jumped on it as I had 5 tons of pellets sitting in my shed since June that I wanted to burn. I also figured that there was not much difference between the two as far as performance.

I had the stove installed a week ago. Everything was working great for the first few days. I then began noticing that there were larger differences between the room sensor setting and what the actual temperature tracked in the room - If I had the stove set for 70 degrees, the room might vary from a low of 66 to a high of 74. I did not think much of that and figured that it was probably normal. This past Sunday night I got a real scare. I had the stove set in room temp mode for the usual 70 degrees; when I woke up dehydrated at 5:00 am and stumbled down the stairs, the room was glowing; the stove was roaring hot! My digital thermometer on the other side of the room said 89 degrees (by the way the outside temp was 29 degrees), the stove was burning hotter than I thought it could get. I could not step on the hearth pad in my bare feet; it was simply too hot to stand it. After turning the stove to off, it continued to feed pellets for 15 minutes before the fire began to drop off and finally went out.

Has anyone else had an experience like the one I just described? I called my dealer and he is researching it with Harmon. His first instinct is that it was caused by a faulty room sensor (the part that plugs into the back of the stove). The stove seems to run fine in the stove temperature mode, and I would not dare run it again in room sensor mode until this is resolved. It also makes me a little leary leaving the stove unattended now. I don't know if it could have gotten hot enough to start a house fire, but I'm telling you that stove, hearth pad, and surroundings were hot enough to be worried. Any thoughts would be appreciated.
 
I've never heard of that before. It was always my impression that there were safety features built in place if it overheated.
 
Turd Ferguson said:
I've never heard of that before. It was always my impression that there were safety features built in place if it overheated.

Is there any evidence that the stove overheated? It definitely sounds like the thermostat stove link is at the least out of calibration or that the thermostat failed. Although I'm sure it was very unsettling or scary, I don't know that the stove overheated. Is there a way to "zero" or calibrate the stat?
 
WOW! I bet it was scary! Stove must have been running at full tilt.
Thought there was a mechanism that would shut it down if it overfired.
 
Where is the room sensor? is it in a drafty area?
I had a basement door near my stove and it was kinda drafty near there so I had to move my sensor up the wall, cause the stove would give false readings.
It is always colder at the floor.........
EDIT***************************
I should add that I would have the dealer come out and plug in the DDM to the stove to see what the ESP and the room sensor are seeing
 
YES YES!!
This has happened to us recently.
Fortunately it happened during the day.
Our dealer suggested moving the sensor more towards the front of the stove.
It was coiled up in back. (Installation guy suggested this)
I did that and have not seen it happen again.
BUT, I think there is more to this than moving the sensor.
The return air to your stove had to have been near 85 at least!!!

Where was your sensor when this happened??
A good way to test is to open a window, put sensor next to screen then close window carefully onto the wire.
The cold air on the sensor should cause the stove to feed pellets and ramp the fire up.
To test for ramping heat down do this: Hold sensor in front of hot air coming out of stove.
The stove should start ramping the fire down.

Good luck!!
Please post any further info you get.

Thanks!!
 
LessOil, My sensor also sits right in back of the stove and sits on the floor, and my installer also suggested this as well. There are no drafts anywhere near this stove. My stove is connected to outside air for combustion. There are many times because of my living situation that this stove will have to go 30 hours unattended - part of the reason that I went with pellets in the first place. I really want to make sure that this issue is resolved. Now we will also see if the dealer is worth his salt. You can really tell after they have your money, and then develop a problem. I will keep people posted.
 
I'd be afraid of that stove. Somethings not right. Check into a complete replacement. Very scary.
 
thats where its nice to have thermostat hooked up to stove have it set at 78 deg. that way the stove is running of of probe but if
room temp. gets above 78 deg. stove shuts down using thermostat just for setback at night and startup in morning. then if temp is reached
harman goes into 4 blink status. skytech 3301p wireless thermostat.
 
I agree with that. I initially thought that hooking up a thermostat could result in nuisance shut downs because my honeywell (RTH230B) only will allow a maximum temperature setting of 82 degrees. But after hearing about the possibility of my Harman going into a thermal run away condition, I am glad I have my thermostat.
 
Thats only if the room sensor is the problem, control board can keep it going, that's why the ddm needs to be plugged in and see what the board is seeing between the probes.
 
Correct me if I'm wrong, but don't all pellet stoves have a high temp sensor that will shut the stove off if the temperature gets too high?

I know my Enviro Meridian does. I had to have it replaced last year when the guy cleaning my stove noticed that it wasn't working properly.

He told me that it was a safety feature that stoves have to stop them from running too high.

Cheap fix ~ $35.00
 
Here are the safely facts for the Harman Accentra according to the manual that came with stove. Just posting as an F.Y.I. Yes I would be calling the dealer and getting them to work on in right away. Good luck.

1) Combusion Motor Fuse - thermal overload one-time fuse link within the motor windings. Should the distribution motor fail with the unit operation over 80%, this fuse will protect the other compondents by melting off at a set temperature. With the fuse blown, the combusion motor will stop, in turn the feeder motor will not operate and the stove will go out. This may happen only when the unit is on Maximum (#7 on the temperature dial, # 6 on the feed adjustment and the distribution blower not operating). If fuse blows unit will need servicing.

2) Control Board/ESP combination is responsible for all high limit safely control. There are two high limits, one normal operation high limit and one backup high limit. The control has an automatic diagnostic circuit that continuously monitors the ESP and Room Sensor for faults. If a fault should occur, the control sends a status alert and at the same time the unit goes down to a minimum feed/minimum burn as a safety condition.

3) The low draft pressure switch is a differential pressure switch that senses the pressure between the firebox and the room. If the pressure becomes too low for proper combustion, the switch opens, turning off the feeder motor and the igniter element. This switch is connected into the A/C (high voltage) wires; therefore, the control may show the feeder motor and igniter lights "on" but they are not.
 
I was also on a waiting list for a P68 and bought a P61A2 that was a floor model (never burned) that became available. We haven't installed our stove yet and I'm glad I read this post because that sounds really scary. I hope that other P61A owners will post their experiences to know if this is a common problem.

I also paid the same price for the P61A2 at a smaller dealer as a P68 at a different, larger Harman dealer. was I wrong to assume that the P68 is more expensive?
 
The P68 probably should be more expensive. It should be a little beefier as it puts out about 700 more BTU, heats about 200 more sq ft. and weighs about 40 LBS. more. Not a hole lot of difference though in my opinion.
 
Sawduster said:
I am a newbie pellet stove owner. I put down a hefty deposit on a Harmon P68 in early June and went through the same thing that everyone else did waiting months for a stove to become available. Finally received a call that I could have a P61a in "honey brown color" for the same price as the P68 so I jumped on it as I had 5 tons of pellets sitting in my shed since June that I wanted to burn. I also figured that there was not much difference between the two as far as performance.

I had the stove installed a week ago. Everything was working great for the first few days. I then began noticing that there were larger differences between the room sensor setting and what the actual temperature tracked in the room - If I had the stove set for 70 degrees, the room might vary from a low of 66 to a high of 74. I did not think much of that and figured that it was probably normal. This past Sunday night I got a real scare. I had the stove set in room temp mode for the usual 70 degrees; when I woke up dehydrated at 5:00 am and stumbled down the stairs, the room was glowing; the stove was roaring hot! My digital thermometer on the other side of the room said 89 degrees (by the way the outside temp was 29 degrees), the stove was burning hotter than I thought it could get. I could not step on the hearth pad in my bare feet; it was simply too hot to stand it. After turning the stove to off, it continued to feed pellets for 15 minutes before the fire began to drop off and finally went out.

Has anyone else had an experience like the one I just described? I called my dealer and he is researching it with Harmon. His first instinct is that it was caused by a faulty room sensor (the part that plugs into the back of the stove). The stove seems to run fine in the stove temperature mode, and I would not dare run it again in room sensor mode until this is resolved. It also makes me a little leary leaving the stove unattended now. I don't know if it could have gotten hot enough to start a house fire, but I'm telling you that stove, hearth pad, and surroundings were hot enough to be worried. Any thoughts would be appreciated.


Go this forum and post in the Harman section and ask for Charlie...for help

http://forum.iburncorn.com/viewforum.php?f=12
 
Sawduster,
Do you have an update for us??
Since my last posting here, I moved the sensor.
It is now on the other side of the room just above our thermostat for the furnace.
The stove seems to be happier with this set up. I soldered all splices I had to make.
This included the push on connector at the stove end.
 
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