Dumb on Btus

This may seem like a dumb question but just would like some expert opinions.
If I have a radiant stove rated at 30,000 BTUs and replaced it with a convection insert stove rated at
90,000 BTUs can I assume I would get three time the heat output. I realize some BTU ratings are not exact, but with everything being equal in my home, would my assumption be correct. I know the convection insert would have the blower fan, but there would also be some radiant output from the cast iron front door as well as the glass, correct ? Thanks in advance for your input.

Koko wrote:can I assume I would get three time the heat output

It depends!! I would say it is safe to assume you will get some multiplier more BTU's, but what that multiplier is exactly would be near impossible to calculate outside of a controlled lab experiment.

To start, the BTU rating may be figured differently for different mfg's. Some ratings may be input BTU's & some output BTU's. And then you get into the efficiency of the stove transferring the BTU's it has inside the firebox out to the room/building itself. What is the sq ft area of the stove available to radiate the heat, how well is airflow around this area accomplished, how well is heat extracted from exhaust, etc, etc.

I can see this one growing into quite a few pages!!

To achieve 30,000 output BTU's burning anthracite (and assuming 75% effiiency) you would need to be burning roughly about 3.3 lbs of coal per hour. That's just under 80 lbs. per day. Doable for many coal stoves I would assume. The heat is in the coal. Roughly 12,150 BTU's per pound on an "as received" basis if you can burn it at 100% efficiency.

The above posts kind of sums it up for me. You did say "Rated" BTU's. So, if the stove is "Rated" to run at 90,000 BTU's, and you have fire to support the BTU rating, it should put out 3 times the BTU's. Now to distribute them BTU's.... If it was 90,000 BTU's MAX, you probably wouldn't want to run at max all the time. You most likely wouldn't run at rated BTU's. But if needed, you can.

Koko wrote:This may seem like a dumb question but just would like some expert opinions.
If I have a radiant stove rated at 30,000 BTUs and replaced it with a convection insert stove rated at
90,000 BTUs can I assume I would get three time the heat output. I realize some BTU ratings are not exact, but with everything being equal in my home, would my assumption be correct. I know the convection insert would have the blower fan, but there would also be some radiant output from the cast iron front door as well as the glass, correct ? Thanks in advance for your input.

I'm no expert but I'm thinking you will be able to get more heat when you need it with the bigger convection insert than with the smaller radiant stove. As mentioned, being able to burn more coal per hour will yield you more BTUs..

The flip side of this of course is that 90,000 BTU's of output requires the burning of roughly 9.9 lbs of coal per hour. Possibly doable for short periods of time, but I'm a bit skeptical.

Thanks for all the input on BTUs. I just wanted to make sure that if I were to move up to a large unit I would get more heat. Right now this radiant small stove holds 5 lbs of coal, (Denmark mfg - multi fuel type) where as the insert hold 45 lbs of coal( USA mfg). I am not expecting to run at full blast, normally average 450-500 degrees, on those very cold days we been have in the northeast. Looks like you have answered my BTU questions - should get more heat with the insert ! ! Kevin.

Just to narrow down this question. So let's assumed we have a radiant stove rated at 30,000 BTUs holds 5 lbs of coal and is burning at 400 degrees vs another radiant stove rated at 90,000 BTUs, holds 40 lbs of coal burning at 400 degrees (would have to assume the 90K is a larger stove). Wouldn't the heat "output" be more on the 90K ? All conditions being the equal, we would just switch out one stove with the other. I know many people start with a small stove then move to a larger stove and they have too much heat in one room and find it difficult to move that heat to other rooms in the house - challenging ! !

I know you didn't ask, but I would be quite interested to know what model Morso you are presently burning -- and what stove you are thinking of switching to.

A stove that holds only 5 pounds of coal is mighty small. One that holds 45 pounds is decent sized, and if rated at 90,000 BTU I expect you will get vastly more heat from it than from the little one, and/or the same heat for a vastly longer time before reloading. Just bear in mind that virtually every manufacturer lies about realistic BTU capacity.

rberq,
Thanks for your response. I have the Morso 1410 which is a multi-fuel stove, the Denmark. mfg claims it is rated at "30,000" BTUs, and I know that is a rating which would be under very exact conditions. I actually purchased it because it fit inside my small fireplace (old house, 1889, which originally used the fireplace to burn canal coal in a basket type grate). Then I saw the Keystoker HF 70/90 HF coal inserts which would fit inside my fireplace. One is "rated" at 70,000 BTUs and the other is a 90,000 BTU rated insert. Appreciate your interest. Kevin.

There is a forum search box at upper right on the screen. You can see what people have to say about Keystoker by searching. I believe Keystoker stoves are highly thought of. I notice that the HF 70/90 can be used with or without a blower. Blowers generally increase BTU output and air circulation substantially, so in my opinion they are worth the money. But they are sometimes noisy. Good luck with whatever you choose, and feel free to come back with more questions if need be.

Koko, the bigger stove at 400 degrees would have more heat output than the smaller stove at 400 degrees because the bigger stove has more heat transfer area.

Lightning,
Thanks for your input, I was thinking exactly the same way, more stove, more heat displacement, or as you stated more heat transfer. Kevin.

Koko wrote:Lightning,
Thanks for your input, I was thinking exactly the same way, more stove, more heat displacement, or as you stated more heat transfer. Kevin.

I guess no one cares that the heat is in the coal. Everyone thinks it is in the stove.

lsayre wrote:I guess no one cares that the heat is in the coal. Everyone thinks it is in the stove.

Well, sure it is.. The coal is in the stove, right??
Kidding of course...