Boiler/wood question

[skeeter2010]

I am not a hvac guy or a math expert,
I am courious about your new boiler you are putting in the addition. You had said you get 16 cords of wood to burn each year. I did some calculations on Btu values http://worldforestindustries.com/forest-biofuel/firewood/firewood-btu-ratings/
I used 25,000,000 btu's per cord x16=400,000,000 btu's. 400,000,000/91,000 btu's per gallon of propane =4,395 gallons of propane

Did the hvac guys give you an idea on how many gallons of propane your new boiler should use per year?
Not that's it's any of my business at all but that seems like a huge amount of propane. Before we converted our house to natural gas we used about 500 gallons a year for heat and hot water for a 2200 sq ft home in southern Wisconsin which I understand will be different.

I am guessing I made a mathematical error someplace

 

[jd]

That's a good question. I did not do the raw numbers calculations, but there will be some pretty big differences between the two systems.

The first being that the gas fired boiler will be much more efficient. I forget the exact number, but something like 93-96. The wood boiler is more like 60%. Add to that the fact that the wood boiler is situated around 100 feet (as the water travels) from the house, so quite a bit of heat is lost as it travels from the boiler to the house. When we put the boiler where we did, we were thinking the main house would be much closer, but ended up just adding onto the cabin, which kept the distance pretty far. The gas fired boiler will be right inside the house, so no heat loss from it to the house.

The wood boiler also burns wood even when the heating system is not calling for heat. Not a ton, but there is still a loss. The gas fired boiler will only be fired when heat is needed.

I also plan to keep the shops a bit cooler and use a wood stove in the woodshop to bump the temp to a comfortable working level. So there will be less fuel used to heat the shops.

My rough calculations put our propane usage at around 1000-1300 gallons, depending on the type of winter we have.

When we first started using the wood boiler, we got our own wood, so it was free. Then a few years later, started taking delivery of logs and the price was around $65 a cord. The past few years, the price of a cord of wood has averaged out to be around $120 a cord.

I suspect that our heating costs will not be way different between the two, but the amount of work sure will be! If I were younger, I would still likely be getting my own wood for free, but that ship has sailed!

-John

 

[slimcake]

You know I always got a kick out of these guys that say they have free heat with wood. Whadda ya got a 10-15K outdoor wood stove. Saws, splitters, countless hours cutting,splitting, stacking, moving, moving again, loading into stove, cleaning stove and so on... Forget it. Dad always said you get heat out of wood heat 8 times.... I got natural gas with an electric backup. Bring it on WINTER!!!

 

[lotoftoys]

I have a wood burning stove in walk out basement that keeps it nice and warm as well as the main floor. The top floor has its own furnace but rarely runs. There is also a back up furnace for main floor when we are away. Yes, two saws , splitter , hauling wood home , splitting stacking. It is out doors and keeps you young. The $? Well my wife loves time under the blanket in front of the wood burner and you know where that leads every now and then! You can't put a price on that guys!