Any pellet furnace experts here?

[newlywv]

I have a Harman PF100 pellet stove in the shop. It suddenly stopped working and upon inspection, I found that if I jump around the low pressure switch it will run. I guessed the switch must be bad and got a new one. After installing the switch, I still need to by pass it for the furnace to run. Any ideas whats wrong?

Thanks

 

[lzenglish]

I have a Harman PF100 pellet stove in the shop. It suddenly stopped working and upon inspection, I found that if I jump around the low pressure switch it will run. I guessed the switch must be bad and got a new one. After installing the switch, I still need to by pass it for the furnace to run. Any ideas whats wrong?

Thanks

Sounds like you may have an ash plugging problem. Does your exaust pipe have a "T" clean-out? If it does, pull the cap and see if it is full of ash. This has happened to me on my whitfield, and I have learned that all the ash will not make the 15 foot trip to the top of my chimney outlet. So, I need to clean it out at least once a season, depending on the brand of pellets I'm burning. I also stick my shop vac nozzel in the 3 inch pipe to pull any ash laying on the sides and ridges of the flex pipe. I always get a full coffee can size out of it after a 3 ton heating season.

Wayne

 

[newlywv]

I took the furnace apart and swept out everything. I am thinking that maybe a heat sensor somewhere on the unit is the problem. I will check out more tomorrow.

Thanks,
Rich

 

[39portlander]

I have been looking @ pellet stoves for a few years and plan on getting one for this fall. The Harman's are some of the best. I actually use a 3" pellet stove brush (local hardware) for other uses.

If it did not come with one, you should be able to get the install manual and in the back section should have a troubleshooting section. Maybe could download that online. Let us know what you find

 

[Zick]

Did you test the new switch to see if perhaps you got a defective one?

Have you checked the hose on the Vacuum pressure switch? It could be plugged.

http://forum.iburncorn.com/viewtopic.php?t=10500&sid=2531a19fe4b0d9e3d4046a92c6d25db2

http://www.thepelletstovecorner.com/tips-ideas/the-vacuum-pressure-switch/

 

[newlywv]

Yes I checked the new switch. It is functioning correctly. The vacuum hose is clear also. I cleaned the whole stove, including the esp probe. Still have the same problem.

Thanks

 

[Zick]

Does it actually startup and run for a short time and then stop or does it just not start at all?

 

[newlywv]

It does start up and try to run. Feeds pellets, blower runs and then stops after short time.

 

[Jefflitzy]

I'm a Harman dealer, by the sounds of your problem it could be a exhaust temp sensor or the circuit board or a weak exaust blower. What is your draft reading from a draft meter gauge, it has to be over .18 or the switch won't close. Also with the stove shutting down This problem is hard to diagnose with out hooking up a Dealer Diagnostic Module (DDM) to the furnace and see the readings off the circuit board to sensor see what the circuit board is seeing. See if you can borrow one from your dealer. All the pressure switch does is turn off the feed motor if the door is left open or there is not enough draft.

 

[bd8134]

If the pellets feed it might not be vacuum switch. On my Harman at least, the vacuum switch is supposed to stop the feeder or auger motor.
Does your model have flashing lights on the circuit panel to indicate what is wrong?

 

[newlywv]

Yes, the status light flashes 5 times.

 

[bd8134]

No expert here, but a flashing light for most Harmans is not burning after a set time.
A few questions.
Presuming here you have not just cleaned or emptied the ash in the burn pot.
On a "cold" start, how many pellets are fed?
Do they come a fair way up the burn pot, at least covering 1/3 - 1/4 of the holes from the ignitor below?
Does the auger or feed motor, feed then stop multiple times?
Do you get any burning or smoldering of pellets by the ignitor below the burn pot?
At what stage do you get the flashing 5?
Have you removed the cover under the burnpot and cleaned the area for the ignitor?
Have you followed or done the complete cleaning procedure as per the manual?

 

[newlywv]

Yes I cleaned as per the manual. The pellets over run the burn pot after a few minutes. and the auger motor does stop and start. After cycling through a couple times the light starts flashing. The ignitor is getting hot and trying to light.

 

[Zick]

It sounds like it's not getting enough air. I was just reading up on this model and it sounds like it has an air intake flapper. Maybe check that out?

 

[bd8134]

As Zick says, it could be the combustion blower not blowing across the ignitor correctly.
It could also be a blockage in the vent pipe as the air cannot blow out.
Blocked holes in the burn pot over the ignitor, weak or faulty ignitor, combustion blower faulty, etc. Let us know how you get on.

 

[Jefflitzy]

5 lights is the stove not igniting on the ignition cycle. How old is the furnace ? there is 2 versions of ignitors pressure and 15 fin. on the 15 fin resistance should be between 48-53 ohms. when was the last time you cleaned inside the little door on the front of the burn pot? have you tried lighting the stove manually? Take a handfull of pellets into the pot and light it with a torch, leave the torch on the pellets for alteast a minute so they are hot and burning. if the ESP dosnt hit 132 the feed motor will not come on, 210 F till the thermostat cuts in to control the feed rate

Had this same issue with my PF100 and it was my ignitor

Jeff

Harman dealer since 1992

 

[joecyr]

Harman Accentra insert. I'm late to the party but had a problem just like this. Turned out the igniter was installed (from the factory) backwards, which aimed it in the wrong direction and would not start the pellets. Since it got hot and everything else worked properly, it was a tough one to fix. Just for grins, one of the two techs turned the igniter around. It's been working fine since then (3 years ago).

 

[Bobmecanic]

I have a Harman PF100 pellet stove in the shop. It suddenly stopped working and upon inspection, I found that if I jump around the low pressure switch it will run. I guessed the switch must be bad and got a new one. After installing the switch, I still need to by pass it for the furnace to run. Any ideas whats wrong?

Thanks

I had the same problem you have now. I checked and replaced the vacum switch but that didn't solve the problem. I was wondering what it could be and I bought a vacum gauge . I took readings through the designated hole and got .62 w.c. , more than enough to make the vacum switch to work (that works at .17 w.c. )if I understood the manual so far. It wouldn't work at .62 w.c. . The combustion chamber is at .62 but the vacum switch didn't kick in, so I took a reading directly on the vacum switch hose and I got only .12 w.c. , I need .17 w.c. to function. As I looked at the vacum switch hose I noticed it went into a pipe that went into the combustion chamber. I looked on the other side of the firepot and found a shroud that covered the end of this metal pipe to protect it from the combustion chamber heat and gases. This shroud has a 1 inch (about) slit. This slit was plugged with carbon and dust. This slit gives the vacum switch enough vacum to work properly, but being plugged it wasn't getting enough vacum to work. I found this by shining a light through air intake and through this metal pipe as I looked from the combustion chamber side ( with mirrors). After cleaning it , everything worked and I got a reading of.23 w.c. on the vacum switch hose.
I hope this works for you.
Bob

 

[Bobmecanic]

I had the same problem you have now. I checked and replaced the vacum switch but that didn't solve the problem. I was wondering what it could be and I bought a vacum gauge . I took readings through the designated hole and got .62 w.c. , more than enough to make the vacum switch to work (that works at .17 w.c. )if I understood the manual so far. It wouldn't work at .62 w.c. . The combustion chamber is at .62 but the vacum switch didn't kick in, so I took a reading directly on the vacum switch hose and I got only .12 w.c. , I need .17 w.c. to function. As I looked at the vacum switch hose I noticed it went into a pipe that went into the combustion chamber. I looked on the other side of the firepot and found a shroud that covered the end of this metal pipe to protect it from the combustion chamber heat and gases. This shroud has a 1 inch (about) slit. This slit was plugged with carbon and dust. This slit gives the vacum switch enough vacum to work properly, but being plugged it wasn't getting enough vacum to work. I found this by shining a light through air intake and through this metal pipe as I looked from the combustion chamber side ( with mirrors). After cleaning it , everything worked and I got a reading of.23 w.c. on the vacum switch hose.
I hope this works for you.
Bob

 

[Jackfre]

Well done, Bob. This is a 9 yr old thread. Oh, and welcome aboard.