Harman P43 Heat Output.

[MrJitters]

Hi all,

I have had my Harman P43 Pellet Stove since 2008. Up until this year I have had no major issues with the stove other then a noisy Distribution Blower that was replaced under warranty.

Recently, I have noticed a reduced heat output from the stove corresponding to the Feed Rate. It has always been my understanding that the feed rate is like a timer. Set the rate at 3 and pellets feed for 30 seconds or so. Now, the stove is running much less then that. Today at feed rate 3 I timed the auger feeding for 12 seconds per minute measured over ten minutes. Not good. I shut the stove off. Unplug it from the wall outlet, plug it back in and it is currently running at feed rate 4 for 38 seconds. This seems to reset something. This may last for a few days, maybe a few more and then it will do it again.

I have been barely able to get 400 degrees out of the stove as measured with a magnetic thermometer on the side of the stove regardless of the setting.

The auger and the Red Feed Indicating LED correspond to each other so there does not seem to be any issue like the auger not running when the LED is lit.

I keep the stove clean. I clean the stove weekly. I vac the flue inside and out. I am using 4" Excel pipe. I am running the stove on Stove Temp, not Room Temp. I would test it on room temp but I cannot find the sensor.

Internet searches seem to point to a faulty control board or ESP sensor, but at this point I am just guessing.

Anyone here with similar issues with their Harman over the years? I would appreciate any input anyone has. I just hate to throw money at guess work.

Thank you in advance.

 

[jzm2cc]

Sounds like an ashed up ESP, or maybe it's just going South.

Try sweeping the control knobs through full range of motion a couple of times. Maybe one if them has a dead spot as stove is in minimum burn or close to it.

 

[MrJitters]

Going south as in the ESP sensor or going south as in the entire stove? LOL. Is the ESP probe the same as the Thermistor probe that is listed in the parts list of the manual?

My short term fix at this point to get me through what is left of the heating season is to reboot the stove periodically.

Status light is not blinking except is Room Temp Mode which it will because there is no probe attached.

 

[Pellettec]

Does sound like a ashed up or faulty esp

The feed rate set at 3 is basically the maximum rate the auger will feed when it calls for heat but it will modulate to maintain the temperature.

I’ve seen the esp go faulty and show a higher temp than the stove was and that showed the same signs as your explaining

 

[Ssyko]

I'm thinking jzm2cc means the ESP sensor is either dirty or may be going bad. Yes it is the thermister probe.

 

[jzm2cc]

LOL, I would have a hard time junking a Harman over a bad probe or control board! Maybe try one of those cheapie $25 probes and see what happens.

 

[MrJitters]

Yeah, me too jzm2cc. LOL. I will look into replacing the ESP probe. Also, another area that seems to draw some attention to this issue is the 3 100K pots on the board. I am pretty handing with a soldering iron so I think this is something I could handle. What say you guys?

 

[greg13]

When was the last time it was thoroughly cleaned? I would pull the connecting pipe between stove & chimney and make sure it is clean with no restrictions. If you have baffles in your stove make sure they are clean also.

 

[Ssyko]

lol funny you ask. i've been researching them for a month. unless your willing to pay 35 bucks for 3 pots that cost .54ea. you can get them on ebay. i found 4 suppliers for the new long life cermet pots but i can't justify the minimum 3000pieces @$5500. i don't have the demand. you can get the carbon style pots through Vimex distributors

 

[jzm2cc]

I've used the ebay 100K and 50K pots to fix 3 and 2 knob control boards successfully in the past.

 

[m159267]

Make sure your esp probe is not covered in ash. Hopefully you have already done this, but if not -- Pull the ash pan, take off the blower cover, then use a flashlight to look down the vent at your esp probe. If it is covered in ash that is likely your problem. Several times each heating season I use a finch feeder brush to keep the vent and probe ash-free. The brush has a long flexible handle and soft bristles that gently brushes the probe. Be very careful whenever cleaning the probe.

 

[MrJitters]

When was the last time it was thoroughly cleaned? I would pull the connecting pipe between stove & chimney and make sure it is clean with no restrictions. If you have baffles in your stove make sure they are clean also.

I anticipated the hassle of routinely taking apart the expensive Excell pipe and risk damaging the gaskets so I put a clean out at the bottom of the vertical riser that goes out through the sill at 8'. So, I clean from the stove along a 5 foot horizontal run to the clean out with a small hose attached to the vac being careful not to damage the probe. Then i run a brush from outside around the elbow down to the cleanout. Lastly I inspect the entire inside of the pipe with a borescope similar to this which works great.

https://www.amazon.com/dp/B074KXB3JM/?tag=hearthamazon-20{creative}&hvpos={adposition}&hvnetw=o&hvrand={random}&hvpone=&hvptwo=&hvqmt=e&hvdev=c&hvdvcmdl={devicemodel}&hvlocint=&hvlocphy=&hvtargid=pla-4584482455193623&psc=1

This cleaning is done every 3-4 weeks. Every week, I am not doing this the stove gets shut down, vacuumed and the ash pan emptied, usually not really needing it.

After the reboot last evening, the stove has been running great. It was -8F this morning air temp and stove temp was 550 - 600F. 650F has traditionally been the max I want to run the stove when it is like -20F to -40F out. At feedrate 3 this morning the auger was running 31 seconds on and 29 seconds off, just like clockwork. At 3 or under, no modulating, just on/off. Nothing wrong with that!!

One of things I do not understand is how a reboot will help if the ESP probe or one or all of the pots are acting up. Not trying to take a cut and dry attitude with it, but one would think if they are broke or not working right a reboot would not help. Usually reboots help with software or firmware issues not hardware issues. Generally speaking.

 

[johneh]

Its like a computer just resets everything where it should be
removes any faults
sorry very simple explanation
Computer guy can give the long winded version
as they say Garbage in Garbage out

 

[MrJitters]

Well, more info to report. I just called my local Harman dealer and by the luck of the Irish I got ahold of their head service tech who was minding the showroom, bored and willing to talk. If he was willing to give me free info, I was willing to listen. LOL. He told me that resetting the stove by shutting it off and unplugging it fixes the issue for awhile tells him there could be some sort of static problem which periodically manifests itself. Unplugging it clears out the bad mojo. I need to be more attentive to unplugging the stove every time I clean it. I should be doing that anyway for safeties sake. He recommended, as well, that come spring to replace the ESP probe like some of you knowledgeable posters here have recommended. It is due to be replaced,

FYI another issue I get is a high pitched harmonic type whine that comes from the auger from time to time. I cannot hear it without my hearing aids on but my wife can. He said to set the stove to stove temp, turn up the feed rate to 6 or max and run that bad boy for 30 minutes. This will clean the carbon deposits off the auger that are causing the annoying harmonic.

Thank you all for all the great advice and taking the time to respond. Have a great weekend all and always keep the faith.

 

[MrJitters]

Its like a computer just resets everything where it should be
removes any faults
sorry very simple explanation
Computer guy can give the long winded version
as they say Garbage in Garbage out

Yep. I look at it this way. Like you, from a layman's perspectiive Think of playing a game of chess. You can set yourself up pretty bad and make it so there's almost no way you can win. If you just restart the game the sequence of events that led you to losing horribly is gone and you are starting over with a fresh start.

 

[David M]

I am going through a similar problem with my Harman XXV. I replaced the ESP (from 2008), but still have the problem. I noticed that the potentiometers are a little loose as I turn them. I just ordered some new upgraded ones off of Ebay. Waiting for some time to replace them.

 

[MrJitters]

I am going through a similar problem with my Harman XXV. I replaced the ESP (from 2008), but still have the problem. I noticed that the potentiometers are a little loose as I turn them. I just ordered some new upgraded ones off of Ebay. Waiting for some time to replace them.

Did you try a reset? I only left it unplugged for about a minute or so. Killing power during a burn sometimes can make things a bit smokey so I did not want to give it much longer.

 

[David M]

Did you try a reset? I only left it unplugged for about a minute or so. Killing power during a burn sometimes can make things a bit smokey so I did not want to give it much longer.

Yeah, I actually had it unplugged for a while when I replaced the distribution blower a few weeks ago.

 

[MrJitters]

OK, cleaned the stove this morning and discovered two things that may be contributing to this issue:

1. Fines chamber was 90% packed tight. Last cleaned 10/15. Totally forgot about that. My bad.
2. Pulled ESP probe and it took a good 5 minutes being very careful to work it out though the hole. I would say a fair amount of carbon deposits on the probe. I am sure most of it got scraped off working it out but I cleaned it right up with some Windex.

Stay tuned.

 

[lightyear]

I am going through a similar problem with my Harman XXV. I replaced the ESP (from 2008), but still have the problem. I noticed that the potentiometers are a little loose as I turn them. I just ordered some new upgraded ones off of Ebay. Waiting for some time to replace them.

You mind posting the guy you ordered them from? I think I need to get some new ones too.

 

[Ssyko]

You mind posting the guy you ordered them from? I think I need to get some new ones too.

Do a search for harmon Potentiometers on ebay. Only one guy selling the long life and he’s charging 35 bucks for 3 pots.

 

[lightyear]

Do a search for harmon Potentiometers on ebay. Only one guy selling the long life and he’s charging 35 bucks for 3 pots.

Thanks. I'm gonna get them. 35 is worth it if they help my stove stay running.

 

[jp99]

OK, cleaned the stove this morning and discovered two things that may be contributing to this issue:

1. Fines chamber was 90% packed tight. Last cleaned 10/15. Totally forgot about that. My bad.

I keep reading about watching the chamber for buildup of fines, but I never get many. I opened mine up after 1.5 seasons - so it's about 3, 3.5 tons - and I had 1/4" of fines in the bottom of my box. I don't clean my pellets before using them, but I am careful not to pour the bottom of bag dust into the hopper.

A bit of an odd mystery to me. Or maybe it's a characteristic of the PC45.

 

[MrJitters]

I keep reading about watching the chamber for buildup of fines, but I never get many. I opened mine up after 1.5 seasons - so it's about 3, 3.5 tons - and I had 1/4" of fines in the bottom of my box. I don't clean my pellets before using them, but I am careful not to pour the bottom of bag dust into the hopper.

A bit of an odd mystery to me. Or maybe it's a characteristic of the PC45.

Thing is when I last cleaned it in 15 it was the first time since I bought the stove in 08 and like you there was very little fines in the chamber. Pretty much a non issue so it kind of got put on the back burner. However, since 15 I changed pellet vendors so this batch, although very good pellets, may just be infected with lots of fines. Sure looks that way. LOL.

Putzing with the stove I have got it to work good right now, but after the heating season ends I shall buy those long life Pots on Ebay and put them in myself. Everything I read on the internet and here indicate the originals pots are living on borrowed time after 11 years.

As for your PC45, if that old corn burner can keep chooglin with corn, a few fines from pellets should not bother her a bit. LOL.

 

[jp99]

I do use corn, but only as an add-in to my pellets. Roughly 15% corn. It breaks up the leftover wood ash better so it falls out of the pot. Without that, almost any pellet brand forms a hard crust I'm cleaning out of the pot 2-3 times a day.

Straight corn, or 85% corn with pellets, is a lot more maintenance. Clinkers to remove, more wear items (stir rod) and the ash can fills up weekly. And then there's the long term corrosion issues. If pellets are close to $/BTU to corn, I'll use them. I can clean the stove once a month that way (I don't burn 24/7 as I have a natural gas furnace - old, inefficient, but working fine at 60 years old).

I agree, must be the pellet brand. I use Somerset and ProPellet and have no problems with either of them for years.