Question on Installing Pellet Stove in Existing Masonary Chimney

[Fencible]

I plan (future) to install another pellet stove in a small basement rec-room. I'm looking at the Enviro-Mini that looks perfect for it. My question: I have a small wood stove that goes through a clay thimble (8") surrounded by a drywall thimble, and then through 8" of concrete to a block chimney lined with tile (8"x8") that's on the outside of my house.

I can't see any way that I could get a flexible SS pipe connected to a SS chimney liner, or to a "T" and then up a liner to the top of the chimney. If I was ever able to manage it, I don't see how it would be an easy annual cleaning job.

Is there any reason why I could not pipe (with Duravent) into the clay thimble and seal around that connection and let the stove vent up the tiled chimney? If not, please explain why not as I can't see why that wouldn't work the same way the wood stove is installed into that same thimble, and sealed around it.

Thanks,

Dave

 

[Mike Wilson]

Won't work, you won't get enough draft with the tiled flue. Compare the area of the 3 or 4" pellet pipe, to the area of the tiled flue, I'm sure the difference will be too great. Pellet stoves need a nice, controlled flue environment. Plus, you've got the "two appliances sharing the same flue" issue which Elk will chime in on within the hour...

-- Mike

 

[Fencible]

[quote author="Mike Wilson" date="1135065638"]Won't work, you won't get enough draft with the tiled flue. Compare the area of the 3 or 4" pellet pipe, to the area of the tiled flue, I'm sure the difference will be too great. Pellet stoves need a nice, controlled flue environment. Plus, you've got the "two appliances sharing the same flue" issue which Elk will chime in on within the hour...


Hi Mike,

Pellet stoves have exhaust blowers. The only time I would think I would have to worry about draft would be if the power were to go off, and then you do get a little smoke in the house if you don't have a good draft.

As for the "two appliances sharing the same flue": The pellet stove would be replacing the small wood stove which is the only entry into the chimney. It was built just for the stove.

 

[Mike Wilson]

Ahhhh... true... forgot about that. So then why not just get a Direct Vent pellet stove and be done with it.

 

[begreen]

Most pellet stoves are direct vent, but sometimes it's more convenient to use a pre-established chimney than punching a hole in the wall. This is especially true when the other side of the (basement) wall is dirt ;-).

 

[elkimmeg]

I 'm not convinced it can't be done. I think you are not looking at the liner install from feeding it through the existing thimble .
Two man opperation one feeding it from the lower level creating the bend and another person with a rope pulling it up.
I believe there is enough flexibility and space to manuaver a 3" pellet liner and not destroy it. The guy at the bottom has to work by the bend a couple feet at a time.

 

[Fencible]

I 'm not convinced it can't be done. I think you are not looking at the liner install from feeding it through the existing thimble .
Two man opperation one feeding it from the lower level creating the bend and another person with a rope pulling it up.
I believe there is enough flexibility and space to manuaver a 3" pellet liner and not destroy it. The guy at the bottom has to work by the bend a couple feet at a time.

Maybe it would be possible. The drawback would be that the stove would have to be removed each year to clean the chimney and it would be a messy job for sure. Venting directly to the tile would allow me to use a regular chimney brush.

All good responses, thanks.

 

[elkimmeg]

I think you are still thinking in terms of wood stove maintance. A pellet srove burns cleaner very little cresote maybe a fines dust in the liner. Code wise Venting into an 8/8 cross-section with a 4" or 3" pipe will not produce enough heat to heat your liner and produce a positive draft flow. Compounding that is if the chimney is exposed to the outside will never draft correctly therefore the stove will never run effeciently. Even with the limited inducement the pellet stoves produce may not be enough.
Again code wise,I could not issue a permit unless that application was listed, meaning just a direct connection to the existing masonry 8/8 flue. It could work, but at what degree of preformance hit, are you willing to accept? Pellets are not cheap. If your stove gets 60% of what it should be producing, you just paid for the liner in your first pallet load. There is a sure fire correct way to match your stove effeciency, That is to install the correct size listed liner. or direct vent it thew a wall. ( a short horrizontal run) What your are suggesting I think it might work? is not the way to go.

Cleaning issues with a full liner I would disconnect the linner and place the end in a bucket and only shift the stove to accomplish this. I had the room, install a tee instead of a 90 degree bend, with a cleanout removable cover

 

[Shane]

I'd highly recommend lining it. For all the reasons stated, in lieu of the exhaust fan pellet stoves typically perform better with a properly sized chimney.

 

[begreen]

Dave, I think you may be able to get the flex 3" pipe thru the thimble. It's worth a try. It doesn't have to take an exact 90 thru the thimble, you have 5" extra to play with. When I put in our stove there were two type of flex available, one was heavy-duty stainless. This stuff was stiff and won't make a tight bend. It was overkill, seemed made for truck exhausts. The other was much lighter guage stainless and much easier to work with.(duraflex ss?) This is what our quad installer recommended I use.

See if you can borrow a short length from your stove dealer as a test. They often have a 4-5ft scrap around. I think it might make the bend. If it does, get the full length you need. Then feed it down from the top to the thimble opening. Maybe put a 45 bend in it beforehand. You might want to put a nylon cord around it as a pull string. It will help if there is one person above and one in the basement. Then when the pipe is at thimble level, grab it and try to yank it through at a 60 deg. angle. It should feed thru, the lighter guage stainless flex is pretty flexible.

 

[Fencible]

See if you can borrow a short length from your stove dealer as a test. They often have a 4-5ft scrap around. I think it might make the bend. If it does, get the full length you need. Then feed it down from the top to the thimble opening. Maybe put a 45 bend in it beforehand. You might want to put a nylon cord around it as a pull string. It will help if there is one person above and one in the basement. Then when the pipe is at thimble level, grab it and try to yank it through at a 60 deg. angle. It should feed thru, the lighter guage stainless flex is pretty flexible.[/quote]

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Thanks, I'll have to take a look at the thinner flex liner. I've never had a chance to see it.

Dave