Pellet ProII only runs on high

[Phil2268]

I have a pellet pro II which is 18 years old. I'm doing a test run after 3 months of non use. I run it on stove temp mode. When I turn the dial down to low it shuts off. It will stay on if I hold the start button down.

Any ideas?

Thanks
Phil

 

[Bioburner]

Sounds like the vacuum switch is opening up on lower settings shutting the stove down. Probably in need of new door gaskets to seal the stove up and maybe a good cleaning of exhaust fan an the exhaust paths. The start button on most stoves circumvents most safety circuits.

 

[MountainSean]

There is no vacuum switch on those old PPII's. I would suspect the pot on the board is going bad. The boards themselves are no longer available but there are people out there who can repair them.

 

[Bioburner]

If its just the pot switch it would be a easy and fairly cheap repair. Good luck

 

[Phil2268]

If its just the pot switch it would be a easy and fairly cheap repair. Good luck

Actually I repaired the board myself about 7 years go. It's actually a two board sandwich. What happened before is the connector that connects the two boards together had a fried wire. It was the 110 hot term. I jumped them with a wire. Worked great. Do you know where I can get the pot? Thank you

 

[Bioburner]

Digikey is one source others have listed sources for electrical components. I replaced the pot switches on two Harman boards but the switches were available on Ebay.

 

[Phil2268]

 

[Phil2268]

Here's the board. How do I know what pot to replace and the specs on the pot?

 

[Bioburner]

The back side of the little buggers are usually marked. There is two that I see on the board and they are if cheap enough why not replace both and not worry about failure of the remaining one and the resulting work and down time?Maybe someone else can chime in with some help. Electronics are not my thing.

 

[Phil2268]

Now I'm confused. I think you're talking about the blue ones. That's the interior thermostat and mode one. Those work fine. I know that because when I turn the dial on the thermostat one it kicks in where expected. The problem is that when the thermostat reads the stove is hot enough the combustion blower shuts down. The combustion blower should simply go from high to low. Low is just to keep the stove from going out. Then it kicks back into high when the present temp drops enough. That's my problem. I assume that high is full voltage and low is much lower voltage which reduces the combustion blower fan speed. I can clearly hear the difference. This is a very old and simply stove. The feed rate is completely manual. That's what I like about it. I know this stove very well and it's so well made. It is possible for me to run it the way it is but controlling the feed rate. It's on high constantly in the winter anyways. I also use it to heat my hot water. So excess heat is stored in water barrels. There's a barrel next to the stove where heat it stored and another one next to my furnace. The furnace barrel has 100ft of pipe in it which preheats the tap water going into the furnace.

 

[Bioburner]

Well looks like your going to have to send it in and have someone clean things up and figure out what's causing that problem. A bit different problem than when the Harman Ps pot does not stop or start the fans etc

 

[johninwi]

If no-one here has an answer try these guys, helpful people over there, much like this site.
They seem more than happy to help the average guy,

http://www.electronicspoint.com/

 

[Phil2268]

I'm not sure what I'm going to do. The thing is that it works and I can control it with the feed rate which is mechanical. I looked at a wiring diagram and the combustion blower has 2 wires that go directly to the board. That tells me the problem is definitely on the board. The combustion blower gets 110v on high and a lower voltage on low. Something on that board is lowering the voltage and it can't be something small for that kind of voltage. I'm shutting the stove down again and I'll see if I can trace terms 6 and 10 on the board. It would be great if I knew what part actually drops the voltage.

http://www.pellet-stove-parts-4less.com/v/vspfiles/assets/Pellet_Pro_IIparts.pdf

 

[johninwi]

From the other post about about the PP2 you've seen the link to a company that specializes in repairs of these boards, nice to know they are available, i bookmarked it.

If this were my project, first off i'd call contact them and ask about turnaround time. You've easily got 6-8 weeks of time to get the stove back in service.
Based on their response i'd have a time frame to tinker with it my self. The other site i linked had a post about fixing a treadmill, the OP had a reasonable understanding of electronics and had performed some simple tests, with a picture of the board, a voltmeter and input from the site he was able to repair it.

I'd get a can of air and clean the board first, you may find a burnt component, or there could be a short in the dust.

Also, not trying to redirect people from this forum, just another site i like.

 

[Phil2268]

Now I have a new issue. I noticed 2 cracks between holes in the burn pot. Keep in mind this stove is 18 years old. There's also a small hump in the area. Anyone know how to repair this. Maybe a high temp epoxy.

Any suggestions would be appreciated.

 

[JDenyer236]

Now I have a new issue. I noticed 2 cracks between holes in the burn pot. Keep in mind this stove is 18 years old. There's also a small hump in the area. Anyone know how to repair this. Maybe a high temp epoxy.

Any suggestions would be appreciated.

Maybe see if a welder can't fill those cracks in? High temp epoxy is unlikely to work. Just a thought.

 

[JDenyer236]

Also I would suspect one of the power transistors is likely bad. The power transistors are the components attached to the heat sink. They are the components responsible for speed control of your various motors. I also see a lot of bridging of components with dust, a tacky dust at that. Clean the board first, especially the chips as they are very sensitive to dust bridging. After cleaning reinsert the board and try it again.

 

[Bioburner]

Now I have a new issue. I noticed 2 cracks between holes in the burn pot. Keep in mind this stove is 18 years old. There's also a small hump in the area. Anyone know how to repair this. Maybe a high temp epoxy.

Any suggestions would be appreciated.

I wouldn't worry about the cracks till they get so large as to allow the pellets to fall though and or larger than the original holes. When they do have a welder use a bit of stainless and stitch things back up. Did it with our Elena last year without issue.

 

[Phil2268]

I saw the one. I've learned it takes the same flame guide and the gasket kits are the same for most models of Harman stoves. That means it should bolt up. I don't care if it's an exact replacement. Does anyone know if it will fit?

(broken link removed to http://www.pellet-stove-parts-4less.com/product_p/1-10-08514.htm)