Thread: greenhouse around OWB

i want to build a small greenhouse around my outdoor boiler..I was hoping to use one or two of those chimney fan driven heat exchangers to help capture some of the waste heat. Ive got to say that my boiler chimney looks like Saturn 5 launch vehicle upside down, with the amount of heat comign out of it. I also expect that there is some residual heat comign off the boiler and chimney.

I figure that raising the ambient temperature around the boiler by at twenty or thirty degrees should improve the performance of the boiler also.

Phase one will be a frame and roof, to just cover the wood, and then phase two will enclose the greenhouse portion..and I would insulate it with a thin layer of spray foam.

Has anyone experimented with a building around thier outdoor boiler?

Check this out: Woodsheds for OWB-Photos?

If you glassed in a big enough area, you would be kiln drying your wood somewhat, which would also increase efficiency.

people with glass woodsheds shouldn't throw logs.

the enclosed area for the greenhouse will be small, but the roof will form areas to protect wood also. Im not intending on using glass, but just a plastic greenhouse fabric or maybe a greenhouse poly product...

Im worried that the air to air heat exchangers wont be able to handle the heat...and that is why Im searching for anyone else that has actually enclosed the OWB..

thanks for the commetns so far!

Hmmm, the main losses in heat for a CB type OWB are the vent fumes out the stack. I was thinking of ducting the stack fumes via a fan into a wood pre-heater/curing room for the firewood (low volume fan only to draw the heat down from the stack, and not increase the airflow in the firebox). Throwing frozen wood into the boiler sucks heat out of the system, so at least you would gain some from pre-heating the wood. The problem is with all the smoke that you would be ducting into the woodpile and shead.

I am not sure about adding more insulation around the boiler itself, which is what a shead around it would be. Adding foam core panels next to the boiler would probably be as beneficial as putting it inside a greenhouse or shead. But most of the heat is going out the stack, and not from the sides of the boiler or from the piping (if they are insulated correctly).

yes, the amount of heat leaving the chimney is huge.

Here is the in chimney heat exchanger i was looking at.

http://www.northerntool.com/webapp/w...1508_200331508

is very affordable and i have been seeing this ad in popular mechanics since i was a kid...

I agree warmer dryer wood woudl make a difference..I would think having the boiler in a 40 degree room instead of a ten degree windy place would make a big difference also. I woudl expect the largest efficiency gain woudl be from the chimney heat exchangers however.

My hope is to have a small raised bed garden in this small room, I expect it will remain above freezing all winter..and on the 37 below nights, i woudl have to cover the plants like i will have to start doing any day now...(41 degrees the other night!)

I will post plans of this greenhouse at some point. I am planning that for the first phase it will just be a unheated cover for my wood, and the following season i will enclose and insulate about a quarter of the space for this greenhouse thing. Hope to start the posts this weekend..

good luck

It looks like you could duct that heat exchanger with a fan and get warm air w/o the smoke. Looks like a good way to recover some lost energy.

I say go for it! I think it would work good.