One Chimney for Two Stoves???

One chimney for two stoves???

PostBy: Tom On: Mon Apr 17, 2006 12:50 pm

Hello all,
I've lurked on this site for months, but never posted.
To say the least I've been impressed with the knowledge and
the time all of you take to help others out.
That said, I hope there's still a few around to see this post before next heating season.
I'm in the Upstate New York area and just finished my fourth heating season with a Hitzer 50/93 EZFLO stove. I've been heating a ranch house. The stove was placed in the basement and I heated about 2200 square feet with ease.
I'll be moving to a 1900 square feet colonial this summer. I need to heat the basement due to an aquarium hobby, so I was concerned that the stove, or any stove could handle three floors. Adding the basement means I'm heating about 2700 squares.
My question is: does anyone have experience with or an opinion about placing a basement stove and a first floor stove on the same chimney. Over and above that, I'm considering a stoker on the main floor. I'm not familiar with automatic stoves, but if this one chimney idea could work, would the operation of a stoker be compromised by another stove operating on the same line?

Thanks in advance.
God Bless America

PostBy: Clinker On: Mon Apr 17, 2006 10:34 pm

I was a heating technician for over 20 years. Worked on mostly oil fired units ....but draft is draft is draft no matter what fuel your burning. You are never supposed to have 2 "units" attached to one flue. In some locations you are allowed to have one small unit (like a gas or propane water heater) sharing one flue pipe with a larger heating unit (boiler, furnance etc) but even then they have to be piped separately and in very close proximity to each other, and both connected into to the lowest part of the chimney. A chimney can produce only so much draft depending on height, construction and outside ambient temperature as compared to flue gas temprature (hot goes to cold and hot air rises thing blah blah blah).
Trouble is, coal does not make very high flue temps (unless over-fired) so your thermal draft will proberly be low to begin with if you were to add another coal burning unit onto the one chimney flue then you would be pretty much cutting the already low thermal draft in half. Remember if the flue gas can't leave the coal stove and chimney fast enough then potentially deadly flue gases will back-up into the house....never ever a good thing.

Didn't mean to ramble short the answer is NO

I am also positive it is against fire codes (and insurance regs)everywhere.

Your better off running an additional steel insulated chimney from the first floor up.

P.S. BTW, Welcome to the board. Good people reside here... and I agree...may God bless America....always.

Please note I edited my post a few times because of multiple spelling errors.
Last edited by Clinker on Mon Apr 17, 2006 10:57 pm, edited 3 times in total.

PostBy: Berlin On: Mon Apr 17, 2006 10:45 pm

go for it, the only thing that really matters is whether the flue will handle the combined exhaust gas volume and still draft well, which it very well may.
Hot Air Coal Stoker Furnace: Will-Burt Combustioneer 77B
Coal Size/Type: Ohio BITUMINOUS pea stoker coal

PostBy: Complete Heat On: Tue Apr 18, 2006 8:35 pm


It is against fire codes and if your insurance company or building inspector finds out they will more than likely make you remove one of the units. A "Class A" chimney for the upstairs unit is the preferred method. Another alternative is a "direct vent" unit. Alaska and Keystoker make some out standing stoker units that will direct vent. Both manufacturers have an outstanding reputation, so the only choice is what kind of unit you like, and whether you want it to be controlled by a thermostat or a rheostat. The rheostat option will put out a continuous amount of heat ranging between 5 to 85k btus. The t-stat option will turn the unit on and off to hold the room at a near constant temperature. Both systems work well.

Complete Heat
Stove/Furnace Make: Axeman-Anderson
Stove/Furnace Model: AA-130/FHA

PostBy: Tom On: Tue Apr 18, 2006 11:46 pm

Thanks for the responses. I guess its a good habit to consider fire codes and insurance regs first instead of last. They're there for a reason.

Complete Heat, are the direct vents relatively efficient?

Thanks to all, Tom

PostBy: Complete Heat On: Wed Apr 19, 2006 9:00 pm


Whether the stove is direct vented or natural vented (chimney or "class A"), the units efficiency is not effected. The benefit to a natural vent is that it is one less thing to go wrong. The down side to a "class A" system is the cost, generally in the $2k range, depending on whether the "class A" is going through a roof or through a wall. If going through a roof, how many floors, is an attic insulation shield required, roof pitch, do you need a roof brace kit? These are all thing that effect the price. A direct vent system is going to be in the $500 range, but will require a little more maintenance, though the maintenance is relatively easy. If you have the ability, I (and the stove manufacturers) would go with a natural vent.

Most of the stoker stoves sold are in the 80-90% efficiency range, which is very good, considering that most furnaces are in that same range.

If you have any more questions, let me know.

Complete Heat
Stove/Furnace Make: Axeman-Anderson
Stove/Furnace Model: AA-130/FHA