Hi. Been around about a year reading and absorbing. I have a 1917 brick bungalow, little to no insulation, new windows. Trying to decide on a Tundra wood furnace or PE Summit insert. I don't see the insert heating the 2 upstairs bedrooms well but I have a concern with the furnace option too. I currently have 2 ducts and a cold air return going to 2nd floor. In my point of view there is no way to ensure 1" clearance to combustibles if I were to hook those up to the tundra. Is there anything I could do, like inserting a 4" duct in the original steel and insulate it somehow? SS liners can be insulated and have 0 clearance so why couldn't duct work? Should I even worry about this?
Ducting furnace to 2nd floor
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DoubleB
Minister of Fire
I faced the exact same question when I installed my Tundra this fall. My solution was to make use of a large preexisting chase on the 1st floor and turn it into a return duct from the upstairs, so no new space or remodeling required. It's sized to pull about 500 cfm from the upstairs. The other return duct (500 cfm) is on the 1st floor; Tundra in the basement. The open stairway is my supply duct upstairs. It works so-so. It's much warmer upstairs now that I pull some of the cold out. But the upstairs is still 5 to 15 deg cooler than downstairs depending upon wind and outdoor temperature. I plan to add another large supply duct at the bottom of the stairs so the warm air isn't as diluted by the time it gets to the route upstairs. That should help. I live in an old farmhouse, so I kind of make do with what I can.
How big is your existing return duct from the upstairs? Can you repurpose it for your wood furnace?
How big is your existing return duct from the upstairs? Can you repurpose it for your wood furnace?
DoubleB
Minister of Fire
Maybe I'm a bit confused...Are your current 2nd floor ducts being used, for example with an LP or oil furnace? Or are they abandonable?
What I meant to ask in my previous post was whether you can dedicate and connect your former laundry chute as a return duct to a wood furnace. The idea isn't to deliver hot air upstairs, rather to draw the cold air out and bring warm air up the stairway as a result.
Based on my house, I'd probably prefer hot air ducts going upstairs, just because the temperature of the hot air, per cfm, is much greater than that of air coming up the stairway if induced by an upstairs cold return. So I agree that hot ducts are better for you if you can manage, and I also am pretty literal and conservative about the manufacturer's clearance to combustible policy.
I'd look at your laundry chute (mine is 6x12), and then consider trying to wiggle a rectangular duct up through it, say a 4.5x10. Put ribs/spacers along it to help maintain clearances if you like. Four-inch ducts inside your existing ductwork might work, although you won't get much air through them in comparison.
Some have accused me of doing things "the hard way" before, but it's also my house and I'm the one who decides that I'd rather engineer risk away than have it lurking...
What I meant to ask in my previous post was whether you can dedicate and connect your former laundry chute as a return duct to a wood furnace. The idea isn't to deliver hot air upstairs, rather to draw the cold air out and bring warm air up the stairway as a result.
Based on my house, I'd probably prefer hot air ducts going upstairs, just because the temperature of the hot air, per cfm, is much greater than that of air coming up the stairway if induced by an upstairs cold return. So I agree that hot ducts are better for you if you can manage, and I also am pretty literal and conservative about the manufacturer's clearance to combustible policy.
I'd look at your laundry chute (mine is 6x12), and then consider trying to wiggle a rectangular duct up through it, say a 4.5x10. Put ribs/spacers along it to help maintain clearances if you like. Four-inch ducts inside your existing ductwork might work, although you won't get much air through them in comparison.
Some have accused me of doing things "the hard way" before, but it's also my house and I'm the one who decides that I'd rather engineer risk away than have it lurking...
DoubleB
Minister of Fire
Another option, probably easier, is to use your upstairs ducts as-is, but to insert a back-draft damper between them and the furnace, the damper closing under gravity but opening under fan power. During a power outage, they should get only a harmless trickle of heat if done properly (if the weight of the damper is more than the buoyancy of the hot air.)
You would need to have enough first-floor supply registers without any restriction from the furnace, however, to help dissipate heat in a power outage.
You would need to have enough first-floor supply registers without any restriction from the furnace, however, to help dissipate heat in a power outage.
DoubleB
Minister of Fire
If you connect a wood furnace to the 2nd floor ducts with a backdraft damper, you might also consider an additional backdraft damper to prevent backwards flow from the wood furnace into the LP furnace.
I like the Tundra. Good bang for the buck as far as I can tell, although I've only operated wood stoves thus far for comparison. My brother in law has a Kuuma and likes it, although I couldn't justify the extra cost.
It took me a while to figure out how to operate the Tundra. That's probably more my fault than the furnace. My wood supply for this year is stuff that burns quickly (box elder, basswood). I only had a year to dry most of it, so I split it smallish. My moisture meter says it's in the 15-18% range. Unfortunately, I'm finding that the wood offgasses so quickly since it's so small and dry that I have too rich a mixture for a short while, after which it's down to coals. I selected bigger pieces that I had drying 2 years, and can get proper secondary combustion, although it still doesn't last as long as I would like. Again, more the traits of the wood than furnace. I found a load of seasoned elm, and it lasted much longer, more as I would expect.
I had two broken parts when the furnace arrived, and SBI shipped replacements no questions asked. Just today I also had to adjust a rod that opens the damper because it wasn't shutting properly in some conditions. Appears to work fine now. All in all I'm happy.
I like the Tundra. Good bang for the buck as far as I can tell, although I've only operated wood stoves thus far for comparison. My brother in law has a Kuuma and likes it, although I couldn't justify the extra cost.
It took me a while to figure out how to operate the Tundra. That's probably more my fault than the furnace. My wood supply for this year is stuff that burns quickly (box elder, basswood). I only had a year to dry most of it, so I split it smallish. My moisture meter says it's in the 15-18% range. Unfortunately, I'm finding that the wood offgasses so quickly since it's so small and dry that I have too rich a mixture for a short while, after which it's down to coals. I selected bigger pieces that I had drying 2 years, and can get proper secondary combustion, although it still doesn't last as long as I would like. Again, more the traits of the wood than furnace. I found a load of seasoned elm, and it lasted much longer, more as I would expect.
I had two broken parts when the furnace arrived, and SBI shipped replacements no questions asked. Just today I also had to adjust a rod that opens the damper because it wasn't shutting properly in some conditions. Appears to work fine now. All in all I'm happy.
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