Chimney Flues and Mutiple Furnaces

Rochester, NY · Post by **Rochester, NY** » Mon. Oct. 31, 2005 7:30 pm

I'm hoping to add a coal stoker boiler to my home. I currently have a good NG boiler and I don't see any reason for getting rid of it (back-up, spring/fall heating, etc...). I can't find any "rules" for venting 2 furnaces through the same chimney flue. Does anyone know what is allowable and what is not?

Mlou · Post by **Mlou** » Mon. Oct. 31, 2005 8:29 pm

You can not mix fuels in the same flue.

Oil Region · Post by **Oil Region** » Wed. Nov. 02, 2005 8:01 am

The instructions in my NG boiler say you should not exhaust the boiler into a chimney with ANY other appliance (such as hot water tank). My boiler has a power vent. I'm assuming one reason a power vent could be dangerous with another appliance is that the power vent could 'push' flew gasses back through the other appliance and into the house. Modern boilers do not have the high temperature exhaust to create a proper draft, so the power vent does the drafting. If there is a down-draft in the chimney, the gases could end up in the house via the other appliance. This is the theory as I understand it, anyway.

Troy