'96 25-PDVP - back burn?

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I have an older 25-PDVP. It's actually been running pretty well so far, after some initial speed bumps. Just before I left for the weekend It took 3 tries to get the thing lit, after a normal cleaning. 2nd try was quite strange....I re-light a pot of pellets, hung around for it to be burning well, with door closed .. had 'sharp' flames, etc. It would normally run for maybe 15 minutes (sometimes less), and the room air blower would kick in, after switching out of SU mode. I smelled smoke while I was taking a shower .... finished up and went down to check .. the fire appeared 'out', and the control board was dark. Slight smoke haze around the stove. I opend the pellet bin, and a bit of smoke was coming out there. I was afraid I had a feed shoot fire / back-burn going on. I turned it on, and the smoke sucked back into the pellet bin, and within 2 seconds, the fire kicked up again. I didn't see any glowing coals before I hit the switch. I hung around for ANOTHER 20 minutes, and it was still in SU mode, even though I'm pretty sure the housing was up to temp ... AND the room air fan was actually already running. Strange. I went to work. My wife called after finally getting up (about 3 hours later) .. and said the control board numbers were at '9-9' .. which is it's normal run setting (it was quite cold).

That was all Friday mrning. I went out of town .. but my wife said the stove appeared to run fine for the day, and when she went down to check the pellets at night, it was almost out, but fire going well. She filled the bin up, and sometime later, the fire apparently went out. She tried lighting it twice, and it didn't keep going, so she gave up. (stove was still warm at this point). I suspect she might have snuffed the fire out when she closed the door, but don't really know. When I got home tonight, I vacuumed out what as was in there, and just for grins, Just turned the stove on to see what was in the feed chute. For what was probably almost the length of the bottom auger tube, it flushed out coarse ash. It had apparently started burning up the feed chute again. Luckily, it snuffed itself out.

Diagnostic runs show everything seemingly working OK ... the draft/exhaust fan, room fan, etc. The heat sensor came back with '86' .. I don't know if that's a code, OHM reading, or is supposed to be the temperature it is reading. The printout of the diagnostics showed an '84' in the screen. It certainly wasn't the temperature, as ambient temp in the room was 52, and the stove felt pretty much the same ... or colder.

Sounds to me like it's not getting enough draft, but the vent pipe seems clear (just cleaned it, and banged some light dust out of it, and I pulled the outside clean-out cap, and that was empty.

Any suggestions?

Well ... before hitting 'post', I went down to check on it again .. it should have been running long enough to 'kick in' again. But ... alas ... fire was out .. staved of pellets. When I hit the 'on' button again, it showed '52' for the numbers, so guess I'll need to go looking for what that means! the auger ran for about 2 revolutions before I started seeing pellets again. May be the upper auger isn't running consistently.

Dennis
 
Replace the gasket between the feed bin lid and the stove. Yours is a positive draft unit. Any leaks through the pellet hopper to the outside will cause burnback which is why they aren't made like that anymore. It's a fire hazard. I had one years ago, it's long gone.
 
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Replace the gasket between the feed bin lid and the stove. Yours is a positive draft unit. Any leaks through the pellet hopper to the outside will cause burnback which is why they aren't made like that anymore. It's a fire hazard. I had one years ago, it's long gone.

Ahh ... good deal. That's easy enough... ;-) I ordered pretty much a full gasket kit when I got it, should they be needed. (ran out of exhaust fan ones, though ...). Sounds like a job for when I get home. Currently, I have it shut down, and will leave it that way for a bit.
 
Replace the gasket between the feed bin lid and the stove. Yours is a positive draft unit. Any leaks through the pellet hopper to the outside will cause burnback which is why they aren't made like that anymore. It's a fire hazard. I had one years ago, it's long gone.
According to the owners manual:
"This unit is equipped with a negative draft system that pulls combustion air through the burn
pot and pushes the exhaust air out of the dwelling."

Could be an air leak at any of the gaskets including the door. Could be an exhaust blower that is shutting down intermittently.
 
According to the owners manual:
"This unit is equipped with a negative draft system that pulls combustion air through the burn
pot and pushes the exhaust air out of the dwelling."

Could be an air leak at any of the gaskets including the door. Could be an exhaust blower that is shutting down intermittently.

Man ... I wish things things had a web interface, that I could go look at an error log! ;-) (hint-hint, for newer boxes!!) I need to get a few more exhaust gaskets. I should probably be pulling that monthly, and I'm not ... but only because I used up my 2 gaskets. I have a new ones for the door and hopper, and will be putting those on tonight. I have some high temp silicone, I could likely use for the exhaust one, until I got proper ones in, but that stuff is such a pain to scrape back off.
 
Man ... I wish things things had a web interface, that I could go look at an error log! ;-) (hint-hint, for newer boxes!!) I need to get a few more exhaust gaskets. I should probably be pulling that monthly, and I'm not ... but only because I used up my 2 gaskets. I have a new ones for the door and hopper, and will be putting those on tonight. I have some high temp silicone, I could likely use for the exhaust one, until I got proper ones in, but that stuff is such a pain to scrape back off.


.... Each time I've been down .. even with the various errors and issues .. unless the stove is stone cold, and fully off .. the exhaust fan has been running. That's not to say it didn't barf earlier to cause the errors, though, I guess. I'm going to keep my fingers crossed that the gaskets do the trick. I'm suspect of the upper auger motor as well. I should probably get one on order.
 
According to the owners manual:
"This unit is equipped with a negative draft system that pulls combustion air through the burn
pot and pushes the exhaust air out of the dwelling."

Could be an air leak at any of the gaskets including the door. Could be an exhaust blower that is shutting down intermittently.

You are right, page 1, I have the manual right here on my desk, however, becauase of the double auger air gap fuel delivery system, it's possible to burn back into the hopper if the stove shuts down with pellets in the lower delivery tube. It's been a very long time since I has mine. I sold it at least a decade ago. I had a burnback issue 2 times and that stuck in my mind but I remember the cause now.

Mine has a full analog control board (2 knob and idiot lights) and what they call a 'temperature probe' on the backside of the firebox on the side opposite the CA fan. No high limit at all and there was no provision for a high limit on the board.

One thing I do rermember was the stove top got very hot during operation, hot enough to burn your hand.

Had to go and dig out the old. musty manual from the file cabinet.
 
I posted this in another post .. but replaced the hopper and door gaskets, pulled the exhaust fan (lucked out and the gasket didn't come apart this time), cleaned and blew all out with an air hose .. especially around the pot, the pot holes, and exhaust. After a good light, it ran for about 20 minutes (about when the room air blower would kick in), and shut down with an E 2 error. :-(
 
You don't have the oem board that came with the stove. The OEM board according to my manual (and what I remember) is an analog 2 knob. Nothing digital.
 
Correct ... it has been replaced at least once. Mike @ ESSW said this box with that board should be set to 'b' mode, and 611. That's what it's on now. I did a board re-set to make sure it hadn't changed (although I had been running at 6-4-1 before that). It's been running for 2 hours now ... on S U mode. Once, it just went quiet .. and the control board dark. Of course, the flame was still going, although wouldn't have lasted long, I suspect. BUT ... might still burn up the shute to the pellet bin, should there still be a bit of available draft there, I suppose.
 
I had a PDVC that my wife was terrified of. When I came home from work I always expected to see that she had thrown it out in the snow bank.
 
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