Wood furnace BTU output

[centennial60]

Does anyone know how the manufacturers figure the BTU output of their wood furnaces? I installed a daka 622 add on wood furnace this fall and it is rated at 125,000 BTU but struggles to heat my 2200 sq.ft. home. I've also got a 68,000 BTU forced air electric furnace that will heat the house with no problem. I would think if the daka really did put out 125,000 BTU that it would be roasting me out of the house.

 

[ericjeeper]

Does anyone know how the manufacturers figure the BTU output of their wood furnaces? I installed a daka 622 add on wood furnace this fall and it is rated at 125,000 BTU but struggles to heat my 2200 sq.ft. home. I've also got a 68,000 BTU forced air electric furnace that will heat the house with no problem. I would think if the daka really did put out 125,000 BTU that it would be roasting me out of the house.

Most of this is configured from firebox size. Are you burning good dry wood? Are you allowing it to burn hot? Or keeping it dampered down trying to get a 12 hour burn?

 

[wdchuck]

We have a daka also. I know what ya mean. Wish I had some solid tips for ya.

 

[CrappieKeith]

The official definition for one BTU is the amount of heat required to raise the temperature of one pound of 60-degree water by one degree at a pressure equal to one atmosphere. In most countries that use metric measurements, the BTU has been replaced by the joule (J). MBTU represents 1,000 BTUs, while MMBTU is equal to 1 million BTUs. A therm is the term for 100,000 BTUs, and the therm is equal to the energy created when burning about 100 cubic feet of natural gas.

When measuring a furnace BTU, manufacturers list the numbers in tens of thousands or hundreds of thousands, and 80,000, 100,000, and 120,000 BTUs are common measurements. Looking at the furnace BTU measurements of various heaters and furnaces is a good way to compare performance levels when shopping. Be certain to look at the furnace BTU output number when trying to determine heat output.

In addition to the BTU measurement on a furnace, you might see an efficiency measurement, such as 80% or 90%, which highlights the heat output of the furnace versus the amount of energy it requires. A more efficient furnace requires less energy to heat the home. All newer furnaces should include a furnace BTU input number and an output number, which reflects the efficiency of a furnace. The difference between these two numbers represents the amount of heat produced (input) to the amount of heat actually delivered to your home (output). Every furnace "wastes" a certain amount of heat.

I have no doubt the Daka is rated at what it says...however to get the heat it says it can make you will burn a ton of wood.
I believe you are also looking for longer burn times. This is an oxymoron with this furnace as it is not capable of generating all of the btu's per lb of wood and give you the type of burn times your wanting or need to keep your home at a comfortable temp.
It's an all or nothing kinda thing.
At some point you may get fed up with it and I'd invite you to look at Yukon's.....we have the attributes to make all of the btus in a lb of wood plus the ability to exchange all of the btus physics say we can only allowing what is nessesary to create a decent draft(400degrees) to go up the flue.

 

[centennial60]

Thanks for the replies. I have been burning mostly seasoned elm and I do have to dampen it down quite a ways to get it to burn all night. When I'm around I will burn it hotter to try and get more heat out of it. Last week when it was cold out I was doing good to get the house up to 65 degrees.

Keith, I have been looking at and reading about the Yukon Super Jack and have been kicking myself for not doing my homework good enough and not buying one instead. I am pretty much fed up with the daka so I am considering buying the SJ hopefully I can sell the daka or maybe I will put it in my shop.

Adam

 

[flotek]

yes everything has a limitation ,but the ouput greatly depends on how its setup the best furnace in the universe wont perform all that great if if its not setup correctly also its only as good as the fuel being used ,wet or partially seasoned wood will only make about half the btus of say hardwood that has over a year of dry seasoning time

 

[John D]

I know what you mean,my OWB is rated at 240,000 BTU's,and it sometimes can't keep up with demand in my home,and my oil fired Weil McClain is 126,000 and it can cycle on and off with all the zones calling,and with me reducing the burner size from a 1.25GPH nozzle to a .85 GPH nozzle....My guess is my oil burner isnt even 100,000BTUs with the nozzle I have...

 

[mtfallsmikey]

I know what you mean,my OWB is rated at 240,000 BTU's,and it sometimes can't keep up with demand in my home,and my oil fired Weil McClain is 126,000 and it can cycle on and off with all the zones calling,and with me reducing the burner size from a 1.25GPH nozzle to a .85 GPH nozzle....My guess is my oil burner isnt even 100,000BTUs with the nozzle I have...

Wood heating appliance BTU ratings are not real accurate in the real world. Type/moisture content of the wood, draft, duct/piping setups have a lot to do with net output as well....at a .85 firing rate, you would get approx. 80-85K. BTU. Most oil boilers are/were oversized, the installing contractor looks at the rating plate, matches up the new/old, collects a check, and moves on....best rating is I=B=R, which tells you the carrying capacity of the boiler in cu. ft. of water.