Jotul Maximum Burn Question.

[Texas123]

This past January when we had the coldest temperatures here in Texas with power outages, I was using the Jotul Oslo 500 for the primary heating. I had the stove going quite well and was using the central heating and ac unit blower only for circulation.

I remember checking the front porch and it was 25 degrees, and in the hallway it was 74 degrees.
The house is 1,666 square feet times (74-25) = 1,664 * 49 = 81,536 BTUs per hour at maximum output.

Jotul rates the Oslo at only 70,000 BTUs per hour, did I do anything wrong or are there calculations on the modest side? I have examined the stove and there are no signs of warping or cracking.

Thanks.

 

[blacktail]

I don't think you're calculating your home's heating needs correctly.

 

[xman23]

I assume you didn't heat the house as well as you expected when the outside temp got down to some low temp. This is not unusual. All of our setups have there limits. So you've got what you've got unless you ID issues you can correct. Here's number questions and issues that I think you should look at. Some or all may help your situation.

How well was the stove running when you had the problem? What was the stove top temperature? It takes me a lot of full loads of good wood, but I can get my Oslo stove top to 650 degrees. If you can't do that, then you have an issue with wood or draft. I never need that kind of temp for my place, more like 450 on the 0 degree days. And much less as the temp goes up. That's only because of my setup.

The stove is a concentrated heat source. It doesn't move the heat to far ends of the house well. You say the house is 74 ft long. Is the stove centrally located? You were using the house blower to move room temp air to unheated rooms. By the time the air moved through the ducts it will cool. Are the ducts run through unheated spaces?

Insulation / Windows are a biggest issue. Are the walls and the windows leaking more cold air in than you have heat.

 

[begreen]

Square feet times the temperature differential does not equal heat loss or BTU production. First, the house is a cube, not a flat area. Ceiling height is important. Then there is insulation and glass area to be factored. And the shape of the house also affects heat loss. A two story square home will lose less heat than a long single story of the same sq. ftg due to more exterior wall area.

If you want a rough guide look up your climate zone. I think it is #3 which requires roughly 40-45 BTUs / sq ft. or about 66,640 to 74,970 BTUs for an average home. If the house is better insulated or if the winter was short or mild, then the number would be less.

Do you have a stove top thermometer on the stove? That will help guide you in preventing overfire of the stove.

 

[Knots]

Add in the house's solar gain too. It's a big difference here living on the north side of a slope vs. the south - even when it's cloudy out. Being sheltered against the north wind vs being out in the open is a big factor too.

 

[nola mike]

...And the thermal mass of the house (important in my case; all brick, no wall insulation).
My best idea to determine heat output is to heat conventionally for a period of time that has similar heating degree days. In my case, pretty easy to see gas usage, which is almost all for heating when the furnace is on. Still a VERY rough estimate.