Need install advise

[pete1018]

I currently have a Regency wood stove that I would like to remove and install in its place my Harman Advance that I brought from my former home. The brick chimney has a 6 inch liner in it about 19ft. I phoned a couple of stove shops that had different advise. One said to use 4 ich pellet vent with a adapter to the liner and the other suggested a 4 inch liner inside of the 6 inch for better draft. One also said I could use my existing 3 inch and use an adapter to the liner. Do they mean an adapter to the thimble? Which is the proper way of doing this. My current 3 inch is Simpson duravent.
Thanks

 

[76brian]

You're in Ontario, which means you'll be getting it WETT certified to make your insurance company happy, right?

If so, you'll have to go inside your existing chimney with 4" pellet stove pipe the entire length, out the top with the proper cap.

The WETT guy who inspected mine said some inspectors might pass it with just an adapter to the 6", but they aren't supposed to.

I was in a similar situation, I just wanted to adapt to the existing 6" pipe I had but was told it would not pass.

 

[whit]

I was in a similar situation, I just wanted to adapt to the existing 6" pipe I had but was told it would not pass.

For those of us not facing inspectors who might one day face the same choice, is it from an operational or safety standpoint a bad thing to adapt to an existing 6" chimney pipe? Does it not draw so well, perhaps? Or is it something that if you try it and it does draw okay, there's no reason aside from keeping the inspector happy not to run with it?

Wondering because at some point I might replace the wood stove at the bottom of a 6" pipe with a pellet stove. But if that means having to run a 4" pipe up the 6" pipe, which seems an absurd expense, it might tilt things back towards just upgrading the wood stove.

 

[DAKSY]

There are a couple of reasons to run the 4" inside the 6"...
1. The cross-sectional area of a 4" pipe is about 12.5 sq.in. &
the cross-sectional area of the 6" pipe is about 28.5 sq. in.
The those two numbers multiplied times the height of the run
will tell you the volume of air your combustion blower will have
to push in order to evacuate the fly ash & any exhaust gasses.
2. If you simply adapt to the 6", any fly ash that falls back before
it's evacuated from the larger vent will fall out when you disassemble
it...

 

[whit]

1. The cross-sectional area of a 4" pipe is about 12.5 sq.in. &
the cross-sectional area of the 6" pipe is about 28.5 sq. in.
The those two numbers multiplied times the height of the run
will tell you the volume of air your combustion blower will have
to push in order to evacuate the fly ash & any exhaust gases.

Thanks for explaining. Now, the exhaust gases are going to rise because they're hot. Of course that's helped if the pipe gets hot, which'll happen more with a smaller pipe. But still, you keep pushing more hot gas in the bottom, the heat itself, not just the combustion blower, will take it upwards. That's assuming there's not a strong wind blowing down from the top though. Have people seen downdraft trouble with 6" pipes up chimneys from pellet stoves?

2. If you simply adapt to the 6", any fly ash that falls back before
it's evacuated from the larger vent will fall out when you disassemble
it...

So more fly ash falls back down the pipe. Right now the pellet stove I have goes 4 feet straight out the wall sideways through a 4-inch pipe, and that collects plenty of fly ash, so I wonder how much would make it up a full chimney no matter what the pipe diameter. Seems you're going to have a significant ash clean out need no matter what the design. If it's falling to the bottom of a 6-inch pipe rather than a 4-inch, it would be falling into a bigger, wider place that could hold more.

 

[Heater Helper]

It,s not just the fly ash but the restriction of a 6" pipe being cold. It could set up a "cold air damn" that the blower can't over come. You could end up with the unti shutting down on you. most have pressure switches to shut the unit down in a blocked flue situation and that could happen.

 

[whit]

It,s not just the fly ash but the restriction of a 6" pipe being cold. It could set up a "cold air damn" that the blower can't over come. You could end up with the unti shutting down on you. most have pressure switches to shut the unit down in a blocked flue situation and that could happen.

Okay, so from the safety POV, if the unit has a pressure switch, then it should shut off just if there's a cold air dam. So barring the failure of the pressure switch you're okay, at worst suffering loss of heat if a cold air dam ever develops?

Given a chimney with a 6" pipe where there's been no trouble kindling fires in a wood stove at the bottom even with the chimney cold, would be reasonable to conclude that cold air dams are infrequent-to-nonexistent in this particular installation? Since the smoke from the kindling makes it up the chimney with no blower at all....

 

[mepellet]

It,s not just the fly ash but the restriction of a 6" pipe being cold. It could set up a "cold air damn" that the blower can't over come. You could end up with the unti shutting down on you. most have pressure switches to shut the unit down in a blocked flue situation and that could happen.

Okay, so from the safety POV, if the unit has a pressure switch, then it should shut off just if there's a cold air dam. So barring the failure of the pressure switch you're okay, at worst suffering loss of heat if a cold air dam ever develops?

Given a chimney with a 6" pipe where there's been no trouble kindling fires in a wood stove at the bottom even with the chimney cold, would be reasonable to conclude that cold air dams are infrequent-to-nonexistent in this particular installation? Since the smoke from the kindling makes it up the chimney with no blower at all....

Does the wood stove have a pressure switch?

 

[whit]

Does the wood stove have a pressure switch?

No. What's your point?

 

[mepellet]

Does the wood stove have a pressure switch?

No. What's your point?

I believe that the pellet stove exhaust is much colder than a woodstove's. Wouldn't overcoming a cold oversized chimney be much more difficult with a pellet stove than a woodstove? Yes the pellet stove does have an exhaust blower but it is still very small and is designed to work within the manufacturer's recommendations.

 

[whit]

I believe that the pellet stove exhaust is much colder than a woodstove's. Wouldn't overcoming a cold oversized chimney be much more difficult with a pellet stove than a woodstove? Yes the pellet stove does have an exhaust blower but it is still very small and is designed to work within the manufacturer's recommendations.

Depends on the size of the fire in the wood stove and the efficiency of it, in terms of what percent of the heat goes up the chimney. In my example of kindling a fire in a wood stove with the chimney cold, at least with my chimney (with a 6" liner) it's enough to start a bit of paper and a few sticks burning, and within a minute the chimney is drawing fine. That's with less heat going up than from a pellet stove, which initially gets hotter quicker. So if the chimney works fine with a wood stove being freshly kindled under a cold chimney and pipe, I can't quite picture the physics of how a "cold dam" is going to stop it from working with a pellet stove, which is initially hotter.

There are many true things that I can't picture before understanding them better. So I'm trying to understand this one better.

 

[Heater Helper]

Exactly..less temps. and volume.

 

[DexterDay]

I believe that the pellet stove exhaust is much colder than a woodstove's. Wouldn't overcoming a cold oversized chimney be much more difficult with a pellet stove than a woodstove? Yes the pellet stove does have an exhaust blower but it is still very small and is designed to work within the manufacturer's recommendations.

Depends on the size of the fire in the wood stove and the efficiency of it, in terms of what percent of the heat goes up the chimney. In my example of kindling a fire in a wood stove with the chimney cold, at least with my chimney (with a 6" liner) it's enough to start a bit of paper and a few sticks burning, and within a minute the chimney is drawing fine. That's with less heat going up than from a pellet stove, which initially gets hotter quicker. So if the chimney works fine with a wood stove being freshly kindled under a cold chimney and pipe, I can't quite picture the physics of how a "cold dam" is going to stop it from working with a pellet stove, which is initially hotter.

There are many true things that I can't picture before understanding them better. So I'm trying to understand this one better.

There are a few members here that have there pellet stove venting into a 6" existing Class A chimney. Doubt it will be much of a problem. Different laws apply to pellet stoves, but as long as your old system drafted fine (not a lot of downdraft) then I doubt there will be any hindering from the pellet stove.

Forum member imacman has his stove vented this way. Has had a couple different models with the same set-up and has no problems. Hell... He holds the record for most bags burned without cleaning or even opening the door to the stove. Maybe the secret is the 6"?? (Doubt it, that was a joke). Send him a PM and ask about his set-up. There are many pics of his stove here. Even some in the Picture Gallery. Beautiful set-up he has.