Hopper Fire last night

What line of venting did that cap come from?

I think you have a neg air problem, you need to get a magnehelic gauge and make sure its within spec of the stove manufacturer. Your comment got me thinking..

"When I ran a wood stove I often had negative draft issues but that was just 6" pipe off the stove and into the wall thimble the dumped into the clay lined chimney."

You would think the combustion fan and the warm air from the igniting pellets would eventually overcome the slug of cold air in the flue.

Is there anything in the house running that would cause a neg air pressure?

I'm with those that suspect negative air pressure in the house. You shouldn't have cold air coming in when you are cleaning the stove.

The OP already mentioned that there is anther burning device in a separate chimney that automatically can cycle and that this end of the basement isn't all that well sealed form the other.

I still have some questions that deal with the gaskets on the pellet stove, if there has ever been any visible warp-age along the door or stove frame due to heat, and if there are any signs of air leakage along the feed system (shows up as v shaped areas pointing to the leak), then there is the ever popular area at the top of the auger flight where there is an end cap that the flight cover sits upon..

In my place, on the first floor or the basement, if the flue gets totally cold there is a downdraft. I might get a bit of a whiff from the basement pellet boiler, but so far so good. I also have to crack a window on the first floor and light a little newspaper for the wood insert if things get totally cold. Does your stove get totally cold? Did it work okay other times from a cold start (and downdraft-can you feel the draft with your hand?)?

Blaming it on the downdraft may be premature, no?

On a side note, my boiler has a little water reservoir that dumps water in the auger tube if things get hot in there.

Did the draft issue when you had your wood insert go away once it got warmed up a little, or was it a constant thing where you always had to crack open a window? I've never experienced it that bad-just a matter of initially reversing the draft.

velvetfoot said:

In my place, on the first floor or the basement, if the flue gets totally cold there is a downdraft. I might get a bit of a whiff from the basement pellet boiler, but so far so good. I also have to crack a window on the first floor and light a little newspaper for the wood insert if things get totally cold. Does your stove get totally cold? Did it work okay other times from a cold start (and downdraft-can you feel the draft with your hand?)?

Blaming it on the downdraft may be premature, no?

On a side note, my boiler has a little water reservoir that dumps water in the auger tube if things get hot in there.

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The OP already had the stove running and had turned it up prior to leaving and the stove wasn't under the control of a t-stat.

So what changed, if it was drafting well when he left? It was a cold day, maybe the oil burner came on? Have they ever both been firing before?

Well I'm just dotting i s and crossing t s.

I want to make sure that the OP can get things back in operation.

Things that separate pressure differences are seals of one variety or another (like gaskets).

Things that lead to pressure differences are differences in altitude between intake and termination and other air handling devices.

Things that interfere with air flow are ash and reductions in the vent system as you get closer to the stove.

As you burn the ash load goes up in the venting this occurs quicker in horizontal runs and elbows adding to the restriction.

What you might not think is a lot of ash can in the right places be a major issue.

Was it windy. Thats the only time ive ever seen a chimney down draft in my 10 years in hvac and usually have a draft regulator on there.ive seen wind blow out an oil burner while running with no draft regulator.Wind or another appliance Maybe attic fan can cause this

Nevermind you did mention it was calm

How many feet in total is your vent run. And have you done the conversion propertys on this run.

For instance I have 13ft of vertical run and the manufactures table converts it to 7.5 feet with the tee and 16inch horizontal. If your manufactures recommended 4inch you should think about trying that. You may just have to much back pressure with the denser air and its having a hard time moving it

Were you running the clothes dryer and exhaust fan the day of the fire?

I am following this thread carefully... I don't like that the cause is unknown

LordmetalZ28 said:

How many feet in total is your vent run. And have you done the conversion propertys on this run.

Click to expand...

He has an equivalent vent length of 15 in just the 90 degree bends alone and 9 in the vertical portion he is definately in 4" vent territory and creeping up on the overall limit.

If he has access to the flue at pellet stove exhaust vent level he would be better off entering the flue that way and 90 degrees and then up. That might even put him in 3" territory.