Venting pellet stoves into masonry flue

[mchappe]

I'm retiring and building one last house. Wife and I have been heating with only wood [no backup] these past 45 years [lately with a Blaze King]. We've been buying tree length maple and oak and working it up with chainsaw and splitter, but as we transition into our [hopefully] golden years, we're thinking about something less strenuous to heat with, such as a pellet stove.
We're planning on a small pellet stove in the finished basement area, and a larger pellet stove in the main living area. We'll also use a cast iron cookstove which will be vented into an 8x12 flue.
Question: Can we use an 8x8 masonry flue to pull fresh air into the two pellet stoves, and another 8x8 flue to vent the burned gases? Do we need to buy the expensive stainless piping, or will the chimney flues suffice? The chimney will rise some 30' from basement through the ridge.

 

[Bridgeman]

I'm not an expert, but two pellets stoves vented into one flue is definitely not going to work or be safe. Pulling the air out might work but separate exhaust and intakes is the way I would go. I would consult the local stove shop about your options for running liners in the existing spaces.

 

[SidecarFlip]

You really need to consult a reputable installer/shop before going any farther or making a decision about multiple stoves.....

 

[BrotherBart]

Virtually all stove makers and localities say not to vent two combustion appliances into a single flue. Maine being an exception, for the life of me I don't know why, and allows it. At least so far. Back drafting of exhaust from one into the other and then out into the living space can easily turn it into not-living space.

As to venting into a masonry flue, I will let the pros here comment on that. Flex liner is cheap for what it does for ya. In your case, maintaining a draft should you have a power failure. The draft would pull the smoke out of the stove and to the great outdoors. As opposed to into your house. It is doubtful that pellet exhaust is hot enough to maintain a draft in 8X8 tile lined chimneys.

 

[bcarton]

I really believe that selecting a good vent is at least as important, and probably more important, than selecting a stove. I bought a pretty primitive old stove, and spent the larger share of my budget on the vent. My vent goes into a liner inside of a masonry chimney. The liner is insulated. The installer tried to convince me that I didn't need either the liner or the insulation. Less than 2 days after I got my stove installed, we had a power outage. No smoke at all got into the house. Power came back on in just few minutes. The stove was still warm and smoldering, pellets started feeding again and the stove came back to life. I never would have known any of this happened except my wife had just gotten home from work and was here when power went out. I did spend a few hundred dollars more, but to me it was very much worth it. My wife would not be at all sold on this pellet stove idea if the house had filled up with smoke or if the CO and smoke alarms started screeching. If we add a second stove, or move to a different house someday, the next install will be done to the same standard.

 

[rona]

I'm retiring and building one last house. Wife and I have been heating with only wood [no backup] these past 45 years [lately with a Blaze King]. We've been buying tree length maple and oak and working it up with chainsaw and splitter, but as we transition into our [hopefully] golden years, we're thinking about something less strenuous to heat with, such as a pellet stove.
We're planning on a small pellet stove in the finished basement area, and a larger pellet stove in the main living area. We'll also use a cast iron cookstove which will be vented into an 8x12 flue.
Question: Can we use an 8x8 masonry flue to pull fresh air into the two pellet stoves, and another 8x8 flue to vent the burned gases? Do we need to buy the expensive stainless piping, or will the chimney flues suffice? The chimney will rise some 30' from basement through the ridge.

I have a friend who does this and gets by with it but I sure won't recommend it. My worry was if the top stove is off the exh from the lower one could back into the top ones pipes. He claimed that wouldn't be possible since the top one has pipe going up 4 feet 90 then straight into the chimney. He claims the natural draft will suck the exh straight up the chimney and not come into the horizontal pipe and down 4 feet into that second stove. I can see his theory but still wouldn't want it in my home.

 

[SmokeyTheBear]

I'm retiring and building one last house. Wife and I have been heating with only wood [no backup] these past 45 years [lately with a Blaze King]. We've been buying tree length maple and oak and working it up with chainsaw and splitter, but as we transition into our [hopefully] golden years, we're thinking about something less strenuous to heat with, such as a pellet stove.
We're planning on a small pellet stove in the finished basement area, and a larger pellet stove in the main living area. We'll also use a cast iron cookstove which will be vented into an 8x12 flue.
Question: Can we use an 8x8 masonry flue to pull fresh air into the two pellet stoves, and another 8x8 flue to vent the burned gases? Do we need to buy the expensive stainless piping, or will the chimney flues suffice? The chimney will rise some 30' from basement through the ridge.

Please note in a new house there is no way you can do the two devices into the same flue in Maine the rule that allows such a connection to exist is to grandfather situations that existed pre- 02/02/1998

From MSRA section 2465 sub section 1-A as enacted by PL 2005.

Rules adopted pursuant to this subsection may not prohibit the continued use of an existing connection of a solid fuel burning appliance to a chimney flue to which another appliance burning oil or solid fuel is connected for any chimney existing and in use prior to February 2, 1998 as long as sufficient draft is available for each appliance, the chimney is lined and structurally intact and a carbon monoxide detector is installed in the building near a bedroom

 

[SmokeyTheBear]

Just for giggles an 8x8 masonry flue is highly problematical for a pellet stove vent, the 64 square inch cross section is well over the 28.27 square inches indicated in most install manuals.

Now there is nothing to prevent you from running two separate 4" PL vents through the same masonry flue because you just made that one flue into two separate flues.

 

[mchappe]

Thanks for all the input. There will be a lined masonry chimney, at least for the cast iron cookstove. Per your comments, I'll have to figure just where/how I can vent the pellet stoves most efficiently and economically. I'll consult the local "experts" who sell the stoves.

 

[SidecarFlip]

Besides, 2 shiny stainless pipes sticking out the top of a chimney cap would look cool.....