There are various wood stove sizing calculators to be found on the internet and they don't all agree. I have a space 11.5' L x 9'W x 8'H that I would like to heat. There is one window, no insulation in the walls, and average insulation in the attic. A Vermont Castings dealer told me a 35,000 BTU stove is fine if I build small fires and crack the window. I have read that building smaller fires leads to more creosote buildup and can ultimately be hazardous. I have found calculators that determine anywhere from 2000 to 12,000 BTUs is appropriate. Where is the original, authoritative source for sizing?
Determine proper wood stove sizing for a space?
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I don't think there is one.
It depends too much on heat loss (not only insulation but also air sealing), sun exposure, outside temperature, what is comfortable to you, how much heat spreads beyond the room etc etc).
Small fires are not necessarily more dirty as long as they burn hot enough. Choked down fires and/or wet wood results in dirty fires.
Do you have current heating in that room and are you able to describe what energy usage is to heat that room now? (E.g. electric space heater kWh usage?)
It depends too much on heat loss (not only insulation but also air sealing), sun exposure, outside temperature, what is comfortable to you, how much heat spreads beyond the room etc etc).
Small fires are not necessarily more dirty as long as they burn hot enough. Choked down fires and/or wet wood results in dirty fires.
Do you have current heating in that room and are you able to describe what energy usage is to heat that room now? (E.g. electric space heater kWh usage?)
There are tons of variables. Are you only looking to heat that space? That’s a really small space.
I would probably opt for a pellet stove so you can get a controllable small output BTU. It would probably be cheaper to insulate the space and use electric convection heaters. A wood stove could drive you right out of there.
Ctwoodtick
Minister of Fire
Agreed , pellet stove has the option of being turned off and the heat stops pretty quickly. Not so with a wood stove.
The space is really small, too small to heat with wood. A small propane heater or electric space heater would be more controllable.
I was thinking something similar. I have watched shows on TV where they have the little houses and some have a tiny wood stove. You would have to cut your own wood really short, and split really small. Maybe burn lump charcoal?
Assuming this space is insured? then if what is needed is permanent heating, it all must be certified for the intended use and inspected.
A portable propane space heater no way. Electric is no problem (and some can do it themselves).
I bought 6 ceiling mount radiant space heaters on sale this year. I have 4 in my garage and 2 in my porch. All applications uninsulated. When I want to warm things up I turn them on and it takes the chill off. I also have a diesel heater in my workshop. If you are not going for "insurance approved'" then I think a $150 diesel heater would do the job.
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The thing is that woodstoves are not a constant output device. The 35000 btu wood heater doesn't make the 35000 all at once but it peaks at 35000 and then trails off to zero. Pulse and glide.
What you're thinking of is a manual J calculation from the HVAC world. That is the thing where you tell it the square footages and insulation types as well as inside and outside temperatures to determine how many BTU the space needs to maintain the desired inside temperature.
Once you have the BTU loss for the space then you need to make that heat. Sure, you can do it with wood. There are folks heating wall tents with woodstoves in camping situations. I've done it! Cooked on it to. We packed that stove and tent on mules. It was great because you could open the door to regulate inside temperature as needed.
What you're thinking of is a manual J calculation from the HVAC world. That is the thing where you tell it the square footages and insulation types as well as inside and outside temperatures to determine how many BTU the space needs to maintain the desired inside temperature.
Once you have the BTU loss for the space then you need to make that heat. Sure, you can do it with wood. There are folks heating wall tents with woodstoves in camping situations. I've done it! Cooked on it to. We packed that stove and tent on mules. It was great because you could open the door to regulate inside temperature as needed.
Although this is only a bit over 100 sqft, a smaller wood stove would be in order, and would probably need to be ran low. Is there a chimney in place to use? If not, I'd suggest a smaller DV gas stove. You still have the ambiance of a pretty flame, reliable heat and could run as needed. Stay warm.
Look at boat heaters from Dickensen. They make them for a variety of fuels.
My house is 900Square feet and I have a 38,000 BTU furnace. I want a wood stove as a backup heat source only to heat one small room so I don't freeze to death during a winter power outage. That's all I want it for. Thanks for responding.
Yes. I am only looking to heat one small bedroom in case of a winter power outage. Just backup heat so I don't freeze to death like people in Texas did two years ago.
I am a prepper. I was wanting wood for self sufficiency. I can harvest wood from my maple trees. I would rather not rely on an outside source for fuel.
No, a small bedroom in my 900 square foot house. I just want the stove for backup heat for one room in case of a winter power outage. I don't want one for regular heating. I have a central air furnace.
Likely it's against code to have a solid fuel appliance in a bedroom.
And it's likely going to be too much unless you get one of those boat stoves mentioned above.
And it's likely going to be too much unless you get one of those boat stoves mentioned above.
It's a bad plan for a wood stove. It's better to put the stove in the living room and sleep there if no power.
A manual J is a calculation approach to calculate how much BTUs you need. I.e. how much heat you loose from the home. It needs specific input like insulation, shading, outside temps etc.
It is used in the HVAC industry but the outcome would be useful independent of what heat input source you use to provide the needed BTUs.
Thank you, everyone. A Vermont Castings dealer determined the Aspen C3 (35,200BTU) would work in my 103.5 square foot space if I built small fires and cracked a window. I trusted him and bought the stove and they installed it. Before I used it, I was told by a friend the stove was way oversized for the space. I called Vermont Castings and the lady on the phone confirmed it. They would not assist me in getting it removed. (This dealer is still in business.) I called The National Fireplace Institute and the Chimney Safety Institute of America. They also confirmed it was way over sized, a safety hazard that could cause oxygen depletion, and warned me not to use it. Neither organization would give me anything in writing. (This dealer is still certified.) The dealer insisted it was fine. He is suing me for not paying off the balance of a stove I haven't used. I need AUTHORITATIVE documentation on sizing to win this in court. No one has been able to tell me where this is. I have researched this to death. I had government inspectors come out and these people are clueless. IRC 1401.3 looks to me to apply to wood stoves. An inspector thinks it doesn't.
There is no authoritative documentation on sizing.
I would look up Kentucky code for wood stoves in bedrooms. It's prohibited in many areas. That is likely the only way to get something out of this.
I believe the NFPA 211 prohibits solid fuel appliances in bedrooms.
The question is whether your jurisdiction defers to the NFPA or not.
I would look up Kentucky code for wood stoves in bedrooms. It's prohibited in many areas. That is likely the only way to get something out of this.
I believe the NFPA 211 prohibits solid fuel appliances in bedrooms.
The question is whether your jurisdiction defers to the NFPA or not.
Unfortunately, there is no Kentucky code. They use IRC. Chapter 14 addresses heating and cooling equipment. M1401.3 says equipment and appliances shall be sized according to Manual J or S. Section M1414 covers fireplace stoves. And yet, this dealer claims a government inspector told him that to apply M1401.3 to this situation is "a misapplication of code." That seems wrong to me.
A Google search of "Does Manual J cover wood stoves?" says it does.
I didn't see anything in NFPA 211 that prohibited a wood stove in a bedroom.
How do you know for sure that there is no authoritative information on sizing? I agree that seems to be the case. But where do all these BTU calculators come up with their figures? There must be a physics/math formula somewhere.
Should I try to get another wood stove dealer or an HVAC dealer as a witness? I must have a witness that this is sized wrong.
Here's the crazy thing. I replaced my 54 year old gas furnace five years ago. It was 60% efficiency. Many of the quotes I got were for the same size input BTUs. But these stoves were 80-95% efficient. (So they were trying to sell me furnaces that were way oversized.) GreenBuildingAdvisor said to get a Manual J. The local utility should have been able to refer me to one, but no one there had ever heard of Manual J. I called numerous HVAC companies and they didn't do them. I finally found one that came out and did it, but they didn't do a blower test. I called someone at the ACCA. He said they didn't do it right. He said it's a problem in the whole industry. But nobody seems to be doing anything about it.
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