Wood stove size

[Montana79]

Hi everyone. I'm in the planning stages of building a 1900 SF single story home in Southwest Montana, zone 6 (I think). I want to include a wood stove as primary heat for all rooms. I'm okay with including attic and/or crawl space duct work to move hot and cold air around. What size and brand stove should I go with? Should I modify anything to ensure good heat distribution? All advice will be greatly appreciated.

--R-19 exterior wall insulation
--R-40 ceiling insulation
--slightly vaulted ceiling in living room/kitchen area (scissor trusses with 8/12 exterior slope reducing to 5/12 inside).
--ceilings drop to 8 feet in hall and bedrooms
--4-foot crawl space throughout, to be insulted as well
--supplemental electric baseboard heat throughout
--35 feet by 55 feet exterior building envelope
--prefer to locate stove in the middle of the living/kitchen area

Thanks!

 

[stoveliker]

Ducts are generally not seen as ideal to move heat from a stove around. Make sure they are completely (!) within the insulated envelope otherwise it's not likely to work.

Returns into duct work can be low at the ground (at least they were in my previous home), leading to them not moving the warmest air that pools near the ceiling.

Now IF you will be able to move the heat efficiently, then I'd go not smaller than 3 cubic foot in firebox size if you intend to heat 24/7 with it.

How tall will the flue be from stove top to chimney cap? It's going straight up most likely (just beside the ridge I presume).
What is your elevation? (Stoves at elevation above sea level generally need more flue height to run well.)

What is your aesthetic preference? Modern, cast iron, (soap)stone?

Pacific Energy, Osburn (or their value brand Drolet), Blaze King (cat stove) are good brands. There are more though.

 

[begreen]

As has been noted many times, ranch homes are not great for heat distribution from a wood stove. The stove room will inevitably be warmer than the far rooms due to the hallway restriction. Convection can be improved by moving cooler air toward the warm room, but for this to work with ducting in a cold space it has to be very well insulated. Cooler air is denser than warm air and easier to move. Working with cool air also means ordinary fans will work without concerns of overheating.

For more even heat in the house option one would be to put a table or box fan at the far end of the hallway, placed on the floor, pointing toward the stove room. Run it on low speed. It will blow the cooler air down low, toward the woodstove. The denser cool air will be replaced with lighter warm air from the stove room. Running this way you should notice at least a 5F increase in the hallway temp after about 30 minutes running.

The other option is a bit more complicated and involves running an insulated duct under the floor with the intakes in the far bedroom floor, tied to a duct that blows out into the stove room. A quiet inline remote bath fan works well for this. The cool air will be replaced with warm air from the stove room. This will require that the bedroom doors be normally open or at least have a 1" gap under the door or a grille in the door to allow circulation.

Another option would be to cut a 6x10 intake grille in the floor of the 2 far bedrooms and run an insulated duct from them into a Y and then a quiet inline 150-200 cfm fan with the output duct going to the stove room. This can be controlled by an air conditioning thermostat in the stove room so that it turns on the fan when the stove room temps exceed a certain temp, say 74º. For best operation, the bedroom doors should be left ajar or the bottom cut up a little (or a grille on the door, etc.) to allow airflow from the room with the doors closed.

Stove sizing will depend on how well insulated and sealed the structure is, ceiling height, and the area of window glazing. Based on what is shown I agree with a 3 cu ft convective stove sizing.

 

[Montana79]

Ducts are generally not seen as ideal to move heat from a stove around. Make sure they are completely (!) within the insulated envelope otherwise it's not likely to work.

Returns into duct work can be low at the ground (at least they were in my previous home), leading to them not moving the warmest air that pools near the ceiling.

Now IF you will be able to move the heat efficiently, then I'd go not smaller than 3 cubic foot in firebox size if you intend to heat 24/7 with it.

How tall will the flue be from stove top to chimney cap? It's going straight up most likely (just beside the ridge I presume).
What is your elevation? (Stoves at elevation above sea level generally need more flue height to run well.)

What is your aesthetic preference? Modern, cast iron, (soap)stone?

Pacific Energy, Osburn (or their value brand Drolet), Blaze King (cat stove) are good brands. There are more though.

Thanks so much for your feedback!

 

[Montana79]

As has been noted many times, ranch homes are not great for heat distribution from a wood stove. The stove room will inevitably be warmer than the far rooms due to the hallway restriction. Convection can be improved by moving cooler air toward the warm room, but for this to work with ducting in a cold space it has to be very well insulated. Cooler air is denser than warm air and easier to move. Working with cool air also means ordinary fans will work without concerns of overheating.

For more even heat in the house option one would be to put a table or box fan at the far end of the hallway, placed on the floor, pointing toward the stove room. Run it on low speed. It will blow the cooler air down low, toward the woodstove. The denser cool air will be replaced with lighter warm air from the stove room. Running this way you should notice at least a 5F increase in the hallway temp after about 30 minutes running.

The other option is a bit more complicated and involves running an insulated duct under the floor with the intakes in the far bedroom floor, tied to a duct that blows out into the stove room. A quiet inline remote bath fan works well for this. The cool air will be replaced with warm air from the stove room. This will require that the bedroom doors be normally open or at least have a 1" gap under the door or a grille in the door to allow circulation.

Another option would be to cut a 6x10 intake grille in the floor of the 2 far bedrooms and run an insulated duct from them into a Y and then a quiet inline 150-200 cfm fan with the output duct going to the stove room. This can be controlled by an air conditioning thermostat in the stove room so that it turns on the fan when the stove room temps exceed a certain temp, say 74º. For best operation, the bedroom doors should be left ajar or the bottom cut up a little (or a grille on the door, etc.) to allow airflow from the room with the doors closed.

Stove sizing will depend on how well insulated and sealed the structure is, ceiling height, and the area of window glazing. Based on what is shown I agree with a 3 cu ft convective stove sizing.

Great tips, thanks!

 

[Montana79]

The other option is a bit more complicated and involves running an insulated duct under the floor with the intakes in the far bedroom floor, tied to a duct that blows out into the stove room. A quiet inline remote bath fan works well for this. The cool air will be replaced with warm air from the stove room. This will require that the bedroom doors be normally open or at least have a 1" gap under the door or a grille in the door to allow circulation.

How much warmer can I expect the room to be if I go with this option?

 

[begreen]

It's hard to say without some trial and error. Best case scenario if the ducting is well insulated, maybe only 5º warmer with a convective stove. There will be some radiant energy from the stove that fans will not change much.

 

[stoveliker]

The increase in farther rooms depends a lot on the temperature in the stove room. If you cook that up to 90 F, your farther rooms will get up more than if you keep the stove room at 75 F..
This is all because a stove is primarily a space heater.

As.an example, I have my stove in the basement. If it's 10 F and howling wind outside, I have the basement at 95 F and my living floor above that at 70 F. And I use a fan to suck cold air from the living room floor and deposit that with a little duct on my basement floor so that the warmest air at the ceiling of the basement gets pushed up the stairs to the living room floor.

If it's 30 F and quiet the basement is 80 to keep the living room at 70.

 

[Montana79]

It's hard to say without some trial and error. Best case scenario if the ducting is well insulated, maybe only 5º warmer with a convective stove. There will be some radiant energy from the stove that fans will not change much.

Will adding insulation into the walls of bedrooms and baths (to blunt sound) inhibit the heat from getting into the back bedrooms?

 

[Montana79]

The increase in farther rooms depends a lot on the temperature in the stove room. If you cook that up to 90 F, your farther rooms will get up more than if you keep the stove room at 75 F..
This is all because a stove is primarily a space heater.

As.an example, I have my stove in the basement. If it's 10 F and howling wind outside, I have the basement at 95 F and my living floor above that at 70 F. And I use a fan to suck cold air from the living room floor and deposit that with a little duct on my basement floor so that the warmest air at the ceiling of the basement gets pushed up the stairs to the living room floor.

If it's 30 F and quiet the basement is 80 to keep the living room at 70.

So if it's 10 outside, and I like to keep my living room at 70, and since I am in a ranch, not a two-story like your house, should I expect even a greater difference in temperature in bedrooms? Say like 20 degrees? And should I just expect to supplement with baseboard heat?

 

[kborndale]

What you need is to create a convection loop. A fan in the floor in the cold room turned on low blowing cold air towards the stove room will help a lot.

 

[stoveliker]

Will adding insulation into the walls of bedrooms and baths (to blunt sound) inhibit the heat from getting into the back bedrooms?

Not much, because the heat will travel mostly through, no *with* the air.

So if it's 10 outside, and I like to keep my living room at 70, and since I am in a ranch, not a two-story like your house, should I expect even a greater difference in temperature in bedrooms? Say like 20 degrees? And should I just expect to supplement with baseboard heat?

It's tough to say, see begreens remarks above.
The question is whether you want even temps or are okay with lower temps in the bedrooms. (I like colder bedrooms.)

Find a way to move.the cold air from the far rooms that hear the stove. Either with a fan in the hallway or with a duct below the floor as long as the space is insulated - and if insulated but not heated, insulated the duct as well to decrease heat loss.
Note that this duct.may need multiple registers (one in the master and one in the other corner room).

I'd for sure add e.g. IR heat in the bathroom to quickly give temps a boost there when desired.

To make the new build comfortable,.do plan on having space localized heat in far rooms that you want at a decent temp.
Whether electric or otherwise, you want to be able to add heat in certain places without adding in the stove room.

 

[begreen]

Will adding insulation into the walls of bedrooms and baths (to blunt sound) inhibit the heat from getting into the back bedrooms?

To a certain extent, yes. It will make ducting from the rooms to pull out cold air and a way for the heat from the stove rooms to enter more important.

So if it's 10 outside, and I like to keep my living room at 70, and since I am in a ranch, not a two-story like your house, should I expect even a greater difference in temperature in bedrooms? Say like 20 degrees? And should I just expect to supplement with baseboard heat?

Without a convection loop it's very possible for the stove room to be 75º and the bedrooms to be at 60º when it's 20 outside.

 

[begreen]

Another possibility is to install a high-efficiency EPA fireplace in the main room and pipe some of the output through insulated ducts, into the bedrooms. This might take rethinking the floorplan a bit. The Study room wall would be a good location, but this may mean switching out the French doors?