Feeding help on a Harman PF-100

[mooseracing]

It's been one of those days and it is leading me down a frustrating path. I have an older Harman PF100 with the 6rpm motor I picked up last fall. It took the place of a wood furnace and I am using a 4" to 6" chimney adapter.

Last fall it worked great, I turned on the propane just to bring temps up quick and the pellet did the heavy lifting after that. I could get it pretty warm in my drafty shop when running it in Auto and the t-stat at 80 or just turning it up all the way manually. At that time I kept an eye on the burn pot and I was within spec as far as about an inch of ash before the pellets when running at max feed.

A few weeks ago when the temps started to drop and I wanted to crank up the temp, I am not getting that level of feeding anymore.

Currently I am lucky if I get a half a pot of pellets. I can also tell the feed rate has dropped off due to the refill timings. Before, I could tell it was doing the max of the book spec at ~13lb/hr.

The last time I was trying to bring the temp up, the auger would only do about one turn and then stop for a quite a bit, then repeat. At that point I cleaned everything out real good including the ESP. Also pulled the auger to verify nothing was stuck in the tube. After, putting it in service and test, it did the same thing - so I bit the bullet on a board.

I recently changed that. The feed seemed better, but it is still not putting enough in there as it did before. An ESP was cheap enough so I just swapped that, but I am no better heat wise. After the old ESP cooled down and I checked it with a DVM, I am getting about 1060 ohms. The new one was 1030. So I still think it is good form what I have read.

So I am stuck now. It was below 0 out today, started with a full hopper and have been running the stove wide open in manual, almost 8 hours later I have about 1/2 hopper still and have added nothing. And it is not that warm in here.

A question I did have, is if the stove is warmed up and you try to do Test mode, is the auger supposed to run the normal test cycle time or does the stove keep an eye on temp and limit that? Because right now if I do that, I get one revolution and thats it.

So some other troubleshooting steps?

 

[greg13]

Test mode does not factor temperature. If you only get half a revolution, something is locking it up. Empty the hopper and see if you can see something locking it up. You may end up pulling the auger out and checking the bearing if nothing else is found.

 

[mooseracing]

If you only get half a revolution, something is locking it up. .

No, not half, it will do a full revolution to dump once. Sometimes during heat cycle It will go around a couple times. I can also go back and fourth with the knob to test, to get it to cycle a few times around. I as well took the side cover off to watch when dumping the pellets into the auger, the slide/door is coming out fully. So i don't think it is dumping a partial load either.

 

[greg13]

If you can separate the motor from the auger you could run in test mode again and see if the motor turns. that should point you either towards the motor side or the auger side.

 

[Former Farmer]

Have you checked your venting? What would happen if the esp was seeing high temperatures because of insufficient airflow going out the exhaust?

 

[mooseracing]

Have you checked your venting? What would happen if the esp was seeing high temperatures because of insufficient airflow going out the exhaust?

That is why I was wondering about test mode and the esp. So today for example, I came out to a cold stove as I turned it off last night. I turned onto test and the auger did 7 dumpings of pellets. I lit them up and got the fire going. I turned her to max, come out later and barely going. Turn the knob to test after it is warmed up, and I only get one dump.

I am actually wondering if it could be in the back of the stove area in the exhaust plugged. The chimney is only a year old and is a 6" one, about 15-20ft long going out the roof. It was drafting fine for the wood furnace that was there last year.

 

[Ssyko]

I would clean the furnace from intake to chimney top. Once verified that it is not plugged up somewhere in the exhaust path then you can do a troubleshooting session. We have seen just cleaned chimneys with unidentifiable chared remains of birds and rodents.

 

[Mr._Graybeard]

My boiler goes into that "fractional-turn-of-the-auger" mode while it's in the ignition phase. Once the pellets are ignited, it starts feeding pellets at full speed. Is it possible that your furnace isn't registering that your pellets are ignited for some reason?

I find that I have to clean my combustion fan regularly to get consistent ignition. I have a later model boiler with the compression ignition system, but other than the placement of the igniter, I would think that the ignition process is fairly similar.

 

[mooseracing]

So I dinked with it a little tonight.

From a cold start, test mode is fine and dumps 7 times. For the first 30mins to an hour, it was putting out the heat I would expect and the pot was full.

Sometime after, it went back to what it is doing, half a pot burn, even though its wide open. Here is the best shot I could get:

burn pot

• mooseracing
• Jan 28, 2019

So I tried test again while it was doing this, and it would only dump once.

Then I pulled the ESP, and let that cool down. Did test and I got the correct 7 dumps. So there is an issue somewhere with what the ESP is seeing or not seeing.

So since the stove was rampped down and I had the ESP out, I took out the combustion fan. I have a snake camera, so I thought I would take a look in the back side of the stove. Nothing stood out except that while I had the fan off and out, the smoke didn't even try to come out there. It was going right by and out the chimney. I was hoping to see if there is crap built up in the back around the ESP, but I could not tell.

At this point in the year that is not that much I can do with the chimney. You can barely get on the roof in the summer due to pitch. When I hooked up the pellet stove, I could see right out the top. The way the steam/heat is coming out the top (its cold here....) and the speed makes me think things are good there.

I'm going to double check the jumpers as well.

 

[propanevictim]

My PF 100 must be going on 10 years now. It's always performed well. In the past I have replaced the feed motor and the dealer early on replaced a vacuum switch. And then there's this year. I have replaced all of the following: vacuum switch, rope gasket for the door, and the new upper baffle with the fire brick on it. The furnace is just consuming too many pellets to maintain our desired temperature. Outside temperatures have not been all that bad lately. I am using four bags a day, running through a ton every two to two and a half weeks. I used to get about a month out of a ton. I have a suspicion that the new baffle design results in less heat transfer--a hunch I will test. I am wondering if other parts that have never been replaced--the motherboard, the combustion blower, the ESP probe, the igniter, the burn pot--have an effect on performance as they age? These things all still work (though the combustion blower is making more noise these days). My basement can be damp in summer. I only recently installed a dehumidifier. Each year I see a little bit more rust inside the furnace.I clean the furnace completely on a regular basis--and no less often this year than any previous year. Any suggestions?