Harman XXV pellet stove has blown 3 Control boards

[Stumpy29]

I have a neighbor ... a sweet little old lady, seriously ... whose Harman XXV stove has blown 3 Control boards. Each instance happens after a commercial power outage.

The first one under warranty and the servicing tech advised her to replace her surge suppressor power strip and replace the APC UPS she was using. She upgraded to a pricy Triplite surge strip and purchased a new APC 750 UPS unit.

The second board failed after a 3 day long power outage. When power restored she turned the stove on and the control board fuse blew immediately. The store she purchased it at was contacted and they sent out a service guy who replaced the board ($400) and recommended running the stove off a dedicated outlet. She had an electrician run a totally separate outlet from her panel.

The third board just blew after the power company had to replace the transformer on her pole. They gave her time to shut down the stove. She turned the stove off, powered down the UPS u it, and turned off the power strip. After the power company restored power she turned on the power strip, turned on the UPS, and turned on the stove ... boom ... the fuse blew immediately!

Needless to say she’s agrivated and so far out $1000 in parts and labor! Does anyone have any idea what the issue could be?

 

[Oregun]

Sounds like her surge suppressor isn't protecting the board. I would install a surge suppressor in the circuit breaker box.
She could also unplug the stove when the stove is not being used.

 

[FirepotPete]

I have a neighbor ... a sweet little old lady, seriously ... whose Harman XXV stove has blown 3 Control boards. Each instance happens after a commercial power outage.

The first one under warranty and the servicing tech advised her to replace her surge suppressor power strip and replace the APC UPS she was using. She upgraded to a pricy Triplite surge strip and purchased a new APC 750 UPS unit.

The second board failed after a 3 day long power outage. When power restored she turned the stove on and the control board fuse blew immediately. The store she purchased it at was contacted and they sent out a service guy who replaced the board ($400) and recommended running the stove off a dedicated outlet. She had an electrician run a totally separate outlet from her panel.

The third board just blew after the power company had to replace the transformer on her pole. They gave her time to shut down the stove. She turned the stove off, powered down the UPS u it, and turned off the power strip. After the power company restored power she turned on the power strip, turned on the UPS, and turned on the stove ... boom ... the fuse blew immediately!

Needless to say she’s agrivated and so far out $1000 in parts and labor! Does anyone have any idea what the issue could be?

She wouldn't happen to have the circuit for the stove protected by a GFCI either at the service panel or the outlet? GFCI's do not play well sometimes if more than one is in the circuit, they also do not play well with other protective devices such as surge protectors that measure jeules. For surge protectors you want the highest jeule rating for the best protection.

I'm surprised that the Triplite failed to protect they are great most of the time and usually carry a guarantee to replace anything they didn't properly protect. I guess it might depend on the model as to coverage and how much they will or might pay out.

 

[Mt Bob]

I know APC says never to plug a UPS into a surge protector. https://www.apc.com/us/en/faqs/FA158852/

 

[MarkF48]

Open or partially open neutral wire on her service drop. The neutral from the street transformer keeps the voltage balanced at 120vac on each circuit leg. If the integrity of the neutral is compromised, the startup current of refrigerators or other appliances that have a high inrush on startup can create a high voltage on the other half of the circuit from a voltage unbalance. Usually this can be seen if lights get particularly bright or dim when an appliance starts up. My 10 amp table saw was doing this when I had a bad neutral. Lighting on other half of the circuit got bright. The power outages or changing out of the transformer created a situation where the house was picked up from a dead state and the startup inrush to appliances likely created a high voltage that may have been the cause of an overvoltage to the Harman. The ground at the breaker box can help balance the voltage, but the resistance of the ground rod usually isn't sufficient to balance the voltage under heavier loading of circuits. The totally separate circuit still may be on the circuit side that gets an overvoltage.
If you have a digital volt meter, measure each circuit side. They should match up pretty closely.

 

[MYS]

I have a Harmon Pellet Stove XXV and it has worked fine for 5 years. Last winter, I noticed it wouldn’t always turn on and I had to shut it on and off. From reading this post I am thinking that power outages, which happen frequently at my house may have caused the initial problem. But I am in despair and don't want to spend more money trying to fix this issue and not getting it right.

This year during my yearly cleaning and maintenance, the stove would not turn on. The repair man replaced the circuit board as it was blown and when he plugged it in, the stove did the same thing- turned on for a few seconds and then switched to power with blinking red light and wouldn’t work. He had to replace the circuit board again as he thought the electrical voltage had blown the first one.

He also replaced the wiring harness and tried another outlet and still didn't turn on. He showed me on his device used to read the outlet used by the pellet stove how the left prong and right prong were very different and that the problem was in the electrical socket and voltage. He then told me to call an electrician to replace or fix the electrical socket.

An electrician came and measured the outlet and said it had 120 V and ran vacuum cleaner off the outlet and said it was working fine.
He didn't see the same fluctuation as the repair man. He said all was fine and must be the stove. I then contacted my utility company and they checked the voltage two times and had readings around 122 and said the voltage is within correct parameters and shouldn’t be causing a problem. Below is what they wrote to me:

"The report from the 2 safety checks completed advise that the 122volt reading in within tolerance for 120volt system, the incident number is 308866 and the previous incident where we checked is incident 308415 on 10/14/2022. Our recommendation would be to upgrade the system if more voltage is desired to run the wood stove but we have to state it is not necessary."

I also bought an APC voltage regulator and this did not help at all. The repairman said this would handle the voltage fluctuation.

The last step to debug this problem was the repairman brought a generator and plugged in the pellet stove and it immediately went on and stayed on burning the pellets well. So the stove works off the generator but not on any other outlet.

I may not have gotten all the terms correctly as I have little to no experience with this kind of thing, but I am hoping someone can help me to understand what I should do to fix this problem. I am desperate and freezing!!

 

[Oregun]

There is a outlet checker you can plug into an outlet that lights up and lets you know if it is wired correctly. Hopefully the electrician checked this. For example if the hot and neutral wires are swapped it will still measure 120v and some things will work ok but not others.
You could try connecting an extension cord from another outlet in a different part of the house to the pellet stove and see how that works.

 

[Mt Bob]

Well, just seems like impossible. But, it must be your house wiring. Most times I have seen combination and intermitten house wiring problems, it is from the feed in wires to the breaker panel are aluminum, and they corrode, and they get loose. But perhaps find a different electrician to check this, first guy does not seem so bright.

 

[MarkF48]

Possibly a neutral wire that has a poor connection. This could be at the distribution breaker box or out on the drop that feeds the house. Symptoms may be lights that either get overly bright or dim when a large appliance or other device turns on and draws a heavy load for a few seconds. A surge of current through one circuit branch may cause a high voltage on the other branch if the neutral doesn't carry the return load as it is supposed to and the current flows from one 240v leg back to the other rather than all back through the neutral. As mentioned aluminum conductors can be prone corrosion and not making a good, solid connection.

 

[MYS]

Thanks for your suggestions. The electrician had

There is a outlet checker you can plug into an outlet that lights up and lets you know if it is wired correctly. Hopefully the electrician checked this. For example if the hot and neutral wires are swapped it will still measure 120v and some things will work ok but not others.
You could try connecting an extension cord from another outlet in a different part of the house to the pellet stove and see how that works.

The electrician did use this to check the outlet and said it was fine and at 120V. He didn't do much more. I have tried almost every other outlet in my kitchen and in the garage and the same result with the pellet stove. I am going to check with the utility company again and I am going to call another electrician, but I still don't fully understand how the generator works with the stove and no electricity in the house works. Thanks for your response, I really appreciate your input.

 

[MYS]

Well, just seems like impossible. But, it must be your house wiring. Most times I have seen combination and intermitten house wiring problems, it is from the feed in wires to the breaker panel are aluminum, and they corrode, and they get loose. But perhaps find a different electrician to check this, first guy does not seem so bright.

Thanks for your reply! I agree that the electrician didn't really know what to do except use that voltage checker. I will call a different electrician for sure.

 

[Oregun]

We had a loose connection on the neutral once. It was on the transformer connection on the power pole. The lineman said water got into the connection and froze at some point causing the problem.

 

[Washed-Up]

You mention generator, could you explain that a bit more? Is a generator powering your whole house?

 

[MYS]

You mention generator, could you explain that a bit more? Is a generator powering your whole house?

The repairman wanted to try a portable generator to bypass the house electricity to see if the pellet stove would work. It did!!
Since my last post, I had another electrician come to the house and he spent over an hour testing the various outlets and he measured 117 at every kitchen and garage socket - the pellet stove is in the kitchen. He went downstairs and took the over off the electric panel and tested both busses and got 117V on each. I called the repairman and he was able to come over to speak with the electrician. His voltage meter measured 122-124 on the same outlet that the stove uses. This is what he had measured earlier. Not sure why the measurements were so off from his meter and the electrician's meter.? ? They plugged the pellet stove into the portable generator again and it immediately started!! The electrician used his voltage meter to test the voltage from the generator and it was 122 v.

So my pellet stove has both the electrician and repairman stumped. The electrician felt that there was nothing wrong in the house except "low voltage" and to call my utility company to check the voltage coming into the house. He did say that even at 117, the stove should work just as all other appliances in the house are working. I don't get flickering lights at all with my power.
Ok, so I called my utility company and they immediately sent out trucks to check the voltage to the house and check the transformer. the voltage coming to the house measured 122-124V. They looked at the transformer and didn't see any problem at all. They actually said that I had my own transformer. The electrician said it had been replaced recently, probably when I called the first time.

So, I am still without a working pellet stove and no one can figure out why the generator power works and nothing in my house works. The electrician suggested I try using a UPS to clean the electricity to see if that might help . So I went to Best Buy and bought one and it didnt help. The repairman is going to call Harmon again to see if they can suggest anything. They thought it was a voltage problem. But it seems that the circuit board is so sensitive that it kicks the unit off when power is not "ideal". The repairman said that Harmon has upgraded their boards recently. My unit is actually 9 years old and I dont think I had to change the circuit board before.

Still stumped......

 

[MYS]

The repairman wanted to try a portable generator to bypass the house electricity to see if the pellet stove would work. It did!!
Since my last post, I had another electrician come to the house and he spent over an hour testing the various outlets and he measured 117 at every kitchen and garage socket - the pellet stove is in the kitchen. He went downstairs and took the over off the electric panel and tested both busses and got 117V on each. I called the repairman and he was able to come over to speak with the electrician. His voltage meter measured 122-124 on the same outlet that the stove uses. This is what he had measured earlier. Not sure why the measurements were so off from his meter and the electrician's meter.? ? They plugged the pellet stove into the portable generator again and it immediately started!! The electrician used his voltage meter to test the voltage from the generator and it was 122 v.

So my pellet stove has both the electrician and repairman stumped. The electrician felt that there was nothing wrong in the house except "low voltage" and to call my utility company to check the voltage coming into the house. He did say that even at 117, the stove should work just as all other appliances in the house are working. I don't get flickering lights at all with my power.
Ok, so I called my utility company and they immediately sent out trucks to check the voltage to the house and check the transformer. the voltage coming to the house measured 122-124V. They looked at the transformer and didn't see any problem at all. They actually said that I had my own transformer. The electrician said it had been replaced recently, probably when I called the first time.

So, I am still without a working pellet stove and no one can figure out why the generator power works and nothing in my house works. The electrician suggested I try using a UPS to clean the electricity to see if that might help . So I went to Best Buy and bought one and it didnt help. The repairman is going to call Harmon again to see if they can suggest anything. They thought it was a voltage problem. But it seems that the circuit board is so sensitive that it kicks the unit off when power is not "ideal". The repairman said that Harmon has upgraded their boards recently. My unit is actually 9 years old and I dont think I had to change the circuit board before.

Still stumped......

To clarify on the generator, it was only used to power the pellet stove, not the entire house.

 

[MarkF48]

When the electrician checked the outlet voltage, did he have any sort of load plugged into the outlet, something that may draw a good amount of current? If it was checked with a digital voltmeter that has a high impedance (ohms) input and no load on the outlet, it could possibly read the 'correct' voltage even if there is a poor connection with resistance in the circuit.
If you don't have a meter yourself, the link below is a meter you can plug in to read voltage as well as other parameters to show current and power draw (handy to have if you want to know the power draw from devices). Plug it in and get a read with nothing plugged into the adjacent outlet. Take a toaster, portable heater, or other appliance that draws 1000-1500 watts and plug it in to the same outlet and turn it on. The voltage should stay up around 115-120 volts if the circuit is working as it should. If the voltage drops significantly there is likely a loose connection or something causing resistance in the circuit.

Alternatively, have you tried the stove on an extension cord to another outlet which would be on a different circuit breaker?

P3 P4400 Kill A Watt Electricity Usage Monitor​

Amazon product ASIN B00009MDBU

 

[Oregun]

If you live in a subdivision you could try running an extension cord to your neighbors house and see if the stove will run.
Did the power company or electrician look at your house power with an oscilloscope looking for noise/distorted waveform?
I guess at this point I would replace the logic board and see if the problem persists.

 

[Mt Bob]

As Mark said, just measuring voltage means little, it should be measured under load. Also, any competent electrician would have done some physical work, checking for loose connections, at outlet, inside fuse box and any other connection boxes.
However, there might be a possibility, your stove has a broken wire(internally,inside the insulation), from the plug end of power cord to the control panel, or wired wrong, which could explain why it will run on a generator.

 

[johneh]

your stove has a broken wire(internally,inside the insulation), from the plug end of power cord to the control panel, or wired wrong, which could explain why it will run on a generator.

The wire is still broken if plugged into a geny or a wall outlet so explain the difference please,
or am I reading it wrong

 

[Mt Bob]

The wire is still broken if plugged into a geny or a wall outlet so explain the difference please,
or am I reading it wrong

House current keeps the "ground" separate from the neutral, but many generators do not. Just my thoughts, I could be wrong.
But, at this point, if I was there, I would be checking every stove wire with an ohmmeter.

 

[gfreek]

If you live in a subdivision you could try running an extension cord to your neighbors house and see if the stove will run.
Did the power company or electrician look at your house power with an oscilloscope looking for noise/distorted waveform?
I guess at this point I would replace the logic board and see if the problem persists.

I was thinking the same thing about "wave form"..... Runs OK on generator, but not in the house. Nothing else in the home seems affected.. Wonder if it still happens if nothing is connected to the board when plugged in the outlet....disconnect all motors and sensors from the harness..... Also stated now using a UPS...Can you post which one ? Something is weird here...

 

[Washed-Up]

Dirty power from the house and better from the generator were my thoughts