Harman P38- Not Feeding Enough

[fatalber]

Hi All,

I appreciate the help you guys offer new guys like me. So, newly installed Harman P38+, old-style control board with 2 knob setup. It is setup with an up and out vent using Selkrik DT, with 4 foot interior vertical.

I started my first fire per the manual, placed unit in TURBO to test operation, both blowers and auger operating fine. Then placed the feed on 1, and had the blower turned to minimum. I placed a healthy amount of pellets in burnpot, level with front edge, soaked in gel, stirred it up and lit it. Closed the door, and let it go for a few minutes. I got anxious and opened the door a few times. Then after maybe 5 mins I put the stove in Feed Rate 3, and blower mid way.

The problem is that the auger doesn't seem to be feeding at a fast enough rate to keep the burnpot full of pellets. The pellets slowly burned down to the auger,and eventually the fire went out due to lack of pellets. The stove was on Feed 3 and midlevel blower the entire time.

Help would be very much appreciated.

 

[fatalber]

Is it normal for the auger be run irregularly? For the first 3-4 minutes, the auger ran for 15 seconds out of every 60. Then it went 60 seconds with nothing, came on for 5, went silent for another 60-75 seconds, came on for 5 seconds. Then it didn't come on for a while and the fire burned down to the auger with no pellets in the burnpot, then the auger came on for 45 seconds straight. I'm very confused.

 

[P38X2]

I would start with checking your gaskets (door, ash pan door, hopper) and cleaning the ESP.

 

[gfreek]

I put mine on 3 or 4 feed. Exhaust blower on. Light it with gel ,torch, or hand sanitizer. I leave my door open a crack till flame is good , close the door and let it go..It'll take you a few times to get it..As P38X2 stated, be sure ESP is clean.

 

[fatalber]

Does this mean the esp should be that silver chrome color a new one is? My esp doesn't have any buildup on it but it is a soot or black color.

 

[Ogilvy]

I'd guess you pot on the control board is bad with dead spots. Loosing its connection and then regaining it. Mine is failing and when I notice it acting up I just give the knob a little tap and it kicks in again.

 

[gfreek]

The ESP will have a coating of ash on it. I sometimes CAREFULLY clean it with a soft bottle brush while in the stove,, It takes a few minutes to start feeding on it's own with a good starter fire..Keep trying, you'll get it if all is OK.. Or like Ogilvy said worst case bad control pot. ESP..Start simple first..

 

[fatalber]

OK. Did dollar bill test on ash pan door and glass door, tight as could be, could not pull bill out. Will clean esp and refire to test the result. Hopefully it is just that and not a pot or board issue.

 

[fatalber]

So I removed the ESP, and there was some residue on it, black and sooty. Gently got almost all of it off so it was restored to its bright shiny silver color. Replaced it and started up a fire per gFreek's instructions. Went well, fire built up, and after 5 minutes or so the distribution blower kicked on. However the auger still hasn't kicked on at all in almost 10 mins and the pellets in the pot are almost gone and are not being replenished.

So the gaskets are fine, the ESP was cleaned, where does that leave us? Perhaps the ESP is bad, or an issue with the pots/PCB? When the stove is off and I put it into test mode by turning the feed rate from 0 to Turbo to 3-4, the blowers come on and the auger turns sometimes, but not every time. Does that help the diagnosis? I also tried cleaning the pots from the outside with electrical contact cleaner.

 

[fatalber]

If I turn the feed rate knob to Turbo, the auger will start up. It seems like this is pointing to dead spots on the pots perhaps? But wouldn't dead spots also affect the blowers, which seem to be functioning appropriately...

 

[fatalber]

Ok, so the fire was almost out due to lack of pellets in burn pot, so I turned feed rate to Turbo. This caused auger to start pushing pellets it, filling the burn pot and giving excellent flame. Then I turned down the feed rate to 4 and the auger is not feeding. My train of though was the Turbo mode just kicks blower to high and feeds pellets at a high rate, independently of the ESP probe, while the lesser feed rates rely on the ESP probe. So this would seem to point to a Bad ESP, unless my logic assumptions are flawed.

 

[gfreek]

Ok. Or a bad or plugged vacuum diff switch..Is there switch on the hopper lid? Don't know when/if they changed.. 1)The lid also needs a tight seal if vacuum system. 2)Also check if motor spins but not auger, which would be a loose hex headed blot on auger or bad gear box.. 3) Also look to the left of the auger motor you'll see a vacuum diaphragm ( differential) switch, clear hose connected to it, with 2 wires, feed in and out. This feeds the motor power when good vacuum... I'd try jumping these. They are just flat spade plugs..

 

[fatalber]

No hopper lid switch, and no gasket on the hopper lid. I'll check the other things mentioned. If it was a vacuum issue, wouldn't that mean the turbo mode would suffer, which it seems like it isn't.

 

[gfreek]

no gasket on the hopper lid

Should be a rubber gasket on hopper lid..You may be correct about running on turbo..on second thought...it still has to go through pressure switch,so I think I'm wrong on that. Apologize..

 

[fatalber]

No I can't tell you how much I appreciate the help. Ive been running all day and on turbo it will heat the downstairs to 83, but as soon as I turn down the feed rate to 5, it will end up burning out. Think I might pickup a new esp, as several threads with the same problem were fixed with it. If that's not it, I'll go to PCB and pots.

I'm hoping the esp is it because it seems unlikely that the entire pot from feed rate 1-5 is a dead spot, but it will engage the turbo every time.

 

[dhall28]

you can check the esp with a multimeter, should be around 500,000 ohms at room temp, 700,000 on a cold pipe around 60 degrees fahrenheit, if you take a match or bic lighter and heat it the resistance should drop down....

 

[fatalber]

Can you give new a quick walkthrough on checking it with the multi meter? Where to place the two meter leads?

 

[dhall28]

with the stove unplugged take the esp off the control board (it uses a single small button you press and than pull on the wires to get it of the board). Most meter leads are too large to fit into the small opening on the plug side of the esp. I have small back probes that go on my meter that work perfect for this so i have no experience with other things but off the top of my head i may look at using a needle or paper clip or something to fit into the plug. Set the meter to ohms and test it. 70 F is around 500,000 while 60 F is around 700,000 and 300 F is around 7,000 ohms, be gentle this stuff isn't made for strength but it can take a little pulling to get the plug off the board, but make sure the button is fully depressed if pulling firmly.

 

[gfreek]

How are you making out ?

 

[fatalber]

Well ordered a new esp for 70, cheapest I found. Waiting on that to arrive. In meantime I'm going to test the esp probe with multimeter per above. Figure if it turns out to be something else I can always return it. Right now I can run the stove on turbo but it really gets cranking, and heats up the walls and hearth pretty good making me nervous. My clearances are almost double recommended from walls, and hearth is ceramic tile, thinsetted to 3/4 inch of durock. So everything was built and setup to or exceeding code but it still makes me nervous.

 

[fatalber]

Update: The new ESP arrived and I installed it. Fired the stove up, and has been running and feeding appropriately on the feed rate of 3-4. So it looks like the ESP was the problem. Have had the stove running for 36 hours with no problems. Looks like the Stove Chows are putting out a decent amount of ash, but I scrape the burnpot whenever I think of it and the stove has shown not issues regarding keeping a flame going. Looking like I am getting 18 hours out of a bag at 3.5 in this weather, which I guess I probably close to normal. Thanks for all of the help, everyone!

 

[ducker]

I'd say that is pretty good length of time at a 3.5 setting. I'd even think you might see 16hrs - it's all kinda vague is it closer to 3, or closer to 4

Will it hold a flame and burn at 2?

 

[gfreek]

Good to hear you are back up and running. I'm going to get a back up ESP just to have on hand..

 

[fatalber]

Ducker- I haven't tried a feed rate of two. I'll try it tomorrow and report back.

Gfreek- thanks for all of the help. I'm glad my limited knowledge and logic landed me on the right answer this time. Just for future ref, when you clean the exhaust with a brush, do you leave the esp in and just be gentle or do you remove it to prevent damaging it?

 

[gfreek]

Take the ESP out when cleaning the exhaust with a brush, other wise you may damage it.. I remove mine and clean it with a damp rag.. When I clean just the stove I use a super soft brush, think it may be a dryer lint brush or drain brush, 29" long I found at the local hardware store and Gently clean the ESP..