Explain BTU's

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xjcamaro89

Member
Feb 1, 2011
112
New Castle, PA
Can someone explain to me how BTUs work. I have a EPA exempt newer stove. It has worked great for how we heat, only for a couple hrs in the evening and then most of the weekend. Its rated to hear 1500 sq ft and 110,000 BTUs. Ive been checkin out some EPA stoves for some longer burn times, and use less wood. I have been looking at a couple stoves that will heat a sq ft area similar to the one i have but the BTUs are much lower like 68,000. How would that effect the way i heat. Here is what i do now. We get home from work and light the stove at like 4-5 pm, and run it until we go to bed, it keeps the one end of the house pretty warm and the other end at least 65*. Which is fine. But because of where the stove is, its on a big enclosed porch that doesnt have a door with a dead bolt, the deadbolt door is the one coming off the porch into the house. So when we go to bed we have to shut the door so we can lock it. Which is fine cause by that time its burned down and we let the furnace take over for the night. What i would like to do is get a high eff. stove and either put a through the wall fan from the porch to the house so we can still lock the door, or get a real outside door for the porch. But i would like to load up the stove and let it burn all night. My current stove would not burn all night. But i high efficient would. But how to the BTUs compare and what would i notice going from a higher BTU stove to a lower? Not as much heat output? Longer heat up times? I dont know if i would want longer heat up times, cause when we get home from work we want it hot and fast. Thanks guys!
 
BTU's is just a measure of heat. Typically, the ratings that you provided of 110,000 or 68,000 is for the number of maximum number BTUs of useful heat the stove provides in an hour. The really rating for heating appliances is typically expressed BTU/hr. The BTU/hr rating does not necessarily mean anything as to to the length of burn time. That is usually determined by the size of the firebox and stove design (mainly cat or non-cat). But usually the larger stoves have the longer burn times and higher BTU/hr output.

A stove with a 110,000 BTU/hr is very, very high output. What brand/model do you have? Typically, a four bedrm house with reasonable insulation has a furnace with an output no greater than 110,000 BTU/hr (much bigger than 1500 sf). A house 1500 sf with reasonable insulation would be overheated with 110,000 btu/hr stove. The problem that you get with a stove with such output is getting the heat to the rest of the house. A furnace of this size needs a ductwork distribution to get the heat spread out to the rest of the house.

Another thing to be aware of is that wood stoves typically only come close to maximum output under the right conditions, i.e., packed firebox, with the optimum wood and draft. And then it will only achieve its maximum output for a portion of the burn cycle, like 2 - 3 hours.

From your description, it sounds like you need to find ways to move the heat out of your enclosed porch.
 
I guess im not worried about moving heat, the way the heat moves now is satisfactory to me (and keeps the furnace off) I guess what i sort of want to know is what am i going to notice about the heat, from a high BTu to a lower one.

Here is the stove i have : http://www.northerntool.com/shop/tools/product_200393570_200393570

And here is the stove im looking at (cause its on sale) : http://www.northerntool.com/shop/tools/product_200316551_200316551

Right now, when we get home from work, when its pretty cold, its around 40* on the porch, the porch is about 20x26. We fire up the stove and within a hour its up to 70*. What would i notice heat wise between those BTU outputs.

If it makes sense to go with a high efficient and keep my good heating cycles, i would probably spring for a decent outside door for the porch so i could lock it all up and leave the door going to the house open so i could heat the house all night. I have a corner door frame fan in the porch-house door to move warm air and it works ery well to move heat into the house.
 
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