Harman Invicible won’t feed to maintain fire

[hockeyonthehill]

Hello,

I have a Harman Invincible wood pellet stove that is causing me some grief. After lighting the stove and turning it on, it seems to burn down to the throat of the burn pot. Even when I crank up the stove temp settings, it doesn't seem to kick into action.

I paid to have it cleaned at the end of the season last year because I thought that this might have been a contributing factor. I just finished "recleaning" the unit discovering everything that wasn't done because it was still dirty inside (can't believe I got soaked $160) -- I removed the distribution and combustion blowers, cleaned the fins and motors (both blowers are working), cleaned the ports for the heat exchanger, unplugged any vent holes in the burn pot. The feed motor appears to be working: the fan spins, the bearing spins around 360 degrees to push the pusher arm down (and up), and what I assume is the tail end of the auger seems to turn around as well. The pusher block pushes and retracts (in fact, when I push the Shut Down button, then the pusher block does kick in as part of the shut down process) and I emptied the hopper and vacuumed out any fines.

Any thoughts on what is going on? Could it be the ESP probe? I haven't removed it yet.

Thanks,

Rob

 

[FireJumper]

It sounds like you have an Invincible "T" model. I would venture to guess that you're assuming correctly. If the probe is reading a higher temperature then the unit really is, the feed motor will not run because of bad readings in the flue (it's thinking your set temperature has been met). Now I believe this unit has an enhancement card located on the main circuit board. This was added to make the unit go into a cycle feed about every minute to allow pellets to purge into the burn pot once your set temperature is met so the unit doesn't go out. If this board is not working properly then you could have two issues at hand rather than one. But I would guess that it's the ESP probe located in the flue.
I would pull the probe out and clean it before replacing it.. Sometimes giving the probe a a good cleaning will make the difference.. Using some type of emory cloth should get all the build up off of it really well. Good luck!

 

[hockeyonthehill]

Thanks for the thoughts. Cleaned the ESP Probe. It was very dirty but it cleaned up. My problem still exists. This unit does have an ESP control board as you mention. Any idea where I could get a replacement part online?

Thanks,

Rob

 

[FireJumper]

I truely believe at this point you want to replace the ESP probe. For some reason it doesn't sound like the ESP probe isn't reading correct temperatures. The reason I say this, is because it sounds like your feed motor operates when it needs to. If the enhancement card was bad the unit would either feed all the time or not feed at all. The ESP probe tells the unit when to feed and when not to feed. So if the temperature reading in the flue is high the ESP probe will tell the control board not to feed. Again I would try the ESP probe first. I believe they are both about the same price.

 

[hockeyonthehill]

Several days later...

Thought you might like to hear that I found the problem with my Harman stove. I was actually the auger itself had become bent or crimped on the one side -- they thought maybe some klinkers or long pellets built up? The pellets were jamming in this shaft because the auger wasn't true. While I pulled the motor off and cleaned it, the auger was the only piece on the stove I didn't remove and inspect (of course!). The auger was replaced for about 90 dollars and the stove is working fine now.

Thanks for your help!

 

[Tim_M]

It sounds like you have an Invincible "T" model. I would venture to guess that you're assuming correctly. If the probe is reading a higher temperature then the unit really is, the feed motor will not run because of bad readings in the flue (it's thinking your set temperature has been met). Now I believe this unit has an enhancement card located on the main circuit board. This was added to make the unit go into a cycle feed about every minute to allow pellets to purge into the burn pot once your set temperature is met so the unit doesn't go out. If this board is not working properly then you could have two issues at hand rather than one. But I would guess that it's the ESP probe located in the flue.
I would pull the probe out and clean it before replacing it.. Sometimes giving the probe a a good cleaning will make the difference.. Using some type of emory cloth should get all the build up off of it really well. Good luck!

I know this is an old post, but I'm trying to troubleshoot a problem with an old Invincible "T" and after reading 100's of posts I stumbled across this one. Your description above of "cycle feed" is exactly what my stove is doing, all the time. As soon as I press start it does just as you describe, cycling the feed motor on for 3-4 seconds every minute or so. It never goes out of this cycle, until I press shut down, when everything stops immediately - blowers and feeder. Does this sound like an ESP problem? Or a board issue? Thanks.

 

[lmjr]

Well, his ESP was GOOD all along...and his was always trying to continue to run.

And yours is doing the opposite...won't continue to run.

In your other post you described a loose connection at ESP...was it a loose/broken wire or just a connector plug came apart?

Sure sounds like the ESP is BAD.

You could determine if ESP is a "OPEN CIRCUIT" by doing a continuity check w/ continuity meter...VOM.

The board would be more difficult to diagnose.

 

[Tim_M]

Well, his ESP was GOOD all along...and his was always trying to continue to run.

And yours is doing the opposite...won't continue to run.

In your other post you described a loose connection at ESP...was it a loose/broken wire or just a connector plug came apart?

Sure sounds like the ESP is BAD.

You could determine if ESP is a "OPEN CIRCUIT" by doing a continuity check w/ continuity meter...VOM.

The board would be more difficult to diagnose.

Yes I was hoping it was the ESP connection, as the metal contacts on the end that plug into the wire appeared to be slightly bent, but I took the plug apart (both sides) and checked the wire connections, and everything looks OK.

I talked to my Harman dealer/service guy, and he's skeptical that the ESP is the problem. He says he's only ever seen one go bad!? But he really didn't have any other suggestions.

After reading everything on this forum, the ESP seems to be the most likely problem. I think I'll spend the $50 and replace it and see what happens. I might try to submit a question to the Harman website and see what they say. But I tried that once before and they weren't very helpful, just referred me to a dealer.