propane furnace

[Mike in Ohio]

I posted earlier asking oil vs propane. I think I will go with the propane, so I have a couple of questions.

The shop is 30 x 48 the furnace will be placed close to a corner of the building.

The furnace is a 65,000 btu out of a mobile home I think.

The vent is only 4" in diameter, it is about 12' to the roof do I need to increase or decrease that as it goes up? I am going to go straight up and out of the roof.

When we put in a wood burner a long time ago, I think we had to have the top of the chimney 2' above anything within 10' of the pipe. Does this sound right?

Can use regular vent pipe untill I get close to the ceiling then go to b-vent so I can scavenge some heat of off the vent stack?

I have to build a plenum for this furnace. The opening on top of the furnace is 14 1/2 x 19 1/2. I was thinking of running the duct work along the ceiling with insulated flexible ducting. Should I put them into the side of the plenum near the top of it, or should I put a couple of 90 degree turns right on top of the plenum and run my ducts from them?

I'm sure I'll have some more questions, thanks for all the help on this board,
Mike

 

[rickairmedic]

Mike by code you are not supposed to have more than 3' of singlewall pipe including 90's ( which each count as 1'). For the Plenum I would just build a sheetmetal box and run your ducts off of it . You can run 4" all the way out however and yes it needs to be at least 2' above the peak of the roof.


Rick

 

[Mike in Ohio]

Thanks Rick,

I wasn't set on the single wall, I just thought maybe I could scavenge some of the heat going up the chimney.

Mike