View Full Version : vent stovehood into furnace exhaust

10-14-2010, 08:59 AM
my furnace and water heater vents through the roof and I need to add a exhaust for my stove top. I was wondering if I could avoid cutting a new hole in my roof and put a T in the furnace exhaust pipe and vent my stovetop through this pipe.

The furnace and water heater are in the basement and the T would be in the ceiling in a single story house in Michigan.

10-14-2010, 09:33 AM
Not a good idea! You could get CO back into the house, and any grease that made it past the hood's filters, might line the furnace flue and create a grease fire. Don't think code would allow it, either. Often, people vent the range out the side, rather than the roof.

10-15-2010, 08:29 AM
What jadnashua said- it's (rightfull) a code-disaster, and a real hazard. If the hood vent is power vented, and the furnace/water heater are atmospheric drafted (likely, if they're sharing a flue) you're guaranteed to be driving copious amounts of exhaust into the basement. Side vent it if you can, but use a decent backflow preventer no matter which way you go with it (roof or side.)

10-15-2010, 11:05 AM
You really want the vent to be as short as possible. The grease filters generally work fairly well, but the warmer the air is, the more the smoke and grease can stay in suspension. Also, smoke particles tend to stick to surfaces, so the fewer elbows you have, the cleaner the vents will stay. The longer things are, the colder things get, and then you start to have problems. A grease fire in the wall is no fun! NEVER run the thing without the filters in place, and if they get replaced, make sure they are the proper ones. Clean them periodically, too!