Poor vacuum on a pellet stove

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buildafire

New Member
Aug 28, 2006
29
Washington
This showed up on a Quad, but could have been any stove. A good reminder to check the venting early...

(From a customer with an error message of low vacuum)


Ok, I have to knock this issue up to experience. But the error code on the panel is an interesting clue.

1) The first thing I did was clean the heat exchanger. I had just cleaned it a week ago but I figured maybe the extra fly ash from the corn I burnt might have plugged it up. Well the heat exchanger was not too bad but I cleaned it anyway.

2) Next I took out the exhaust fan and cleaned it off, and as much of the inside of the exhaust manifold I could get into. It was dirty and there was considerable build up. At least it seemed like quite a bit, but since I did not have anything to reference my observations to, it probably was normal buildup for the amount of pellets I have used. (I've put though a little more than a ton of pellets through it now.)

3) I cleaned the pot thoroughly. Making sure the igniter was definitely clear. I've been trying different techniques to clean the pot. I think I've finally hit the best cleaning scenario that minimizes effort and maximizes the cleaning job. I need to try it out a few more times till I can say it will work 100% of the time.

I then tried to start the stove. It immediately threw a "Vacuum switch Error".

4) I checked the vacuum line and connections and I ran a pipe cleaner through the vacuum port on the feed drop tube to ensure it was clear.

Tried to start it again, no luck vacuum error.

5) Took a jumper wire and jumped the switch. Immediately the stove began the start cycle. The pot smoked and smoked then finally started. I checked the vent output and there was smoke coming out as well as some smoke coming out of the vent tube along some of the seams that were not absolutely sealed. The fire was lazy and un-energetic.

I shut the stove down and I began scratching my head. There obviously was some kind of restriction. Out of desperation I took a ladder and peered into the vent tube outside. Ahhh, now I see the problem.

The end of the vent tube is section that has a tapered end with a screen on the end of it. My description is poor but the tapered piece is to prevent water from coming in the pipe and the screen well the purpose of that is obvious. The screen was so full of fly ash that it had created a tremendous amount of back pressure into the stove causing all my symptoms.

6) Cleaned the screened section on the end of the vent tube and the vertical section of the vent. Cleaned whatever was in the trap inside the house.

I then started up the stove again. Back to running like it did in the beginning, nice bright energetic flame.

So I think I would have to say that had I been more experienced with this kind of setup the issue would have been obvious. But at least now I know what symptoms to took for and the problem areas to check.

Cheers
 
Screen in your Pellet vent cap?
I did not know any pellet stove Vent makers make a cap with a screen.
In 1990 duravent had screens on their caps but the pluged up in cold damp weather and they stoped putting them in in 91
 
Are you saying that it plugged with only 1 ton being run through the stove?
Cause thats alot of fly ash...
How far a pipe run is that?
 
Any pellet stove with a screen in the cap will plug it up.
the low Temp of the Gases with fly ash and Damp weather will plug up even with the best of pellets.
 
Don't know the venting length. Just a reminder to others to look in the spots that don't take a screwdriver and flashlight first... I seem to always forget that and end up feeling silly.
 
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