backdraft

[Jay H]

I've been burning now for the most part part-time since end of november... I'm very occasionally getting backdraft problems via my vent for my bathroom (ceiling fan) and perhaps the vent for the shower/sink. I believe the shower and sink plumbing is vented by code to a small 3" (guestimate) pipe that just barely sticks above my roof. The bathroom fan is vented to a louvred square vent too.

If I'm getting smoke occasionally coming through the small 3" pipe, what is the standard way to prevent this? Some kind of directional piping to point the tube away from my chimney or to raise it higher than the flue for my stove?

Jay

 

[MountainStoveGuy]

I would say raise your chimney, if you get more above your 15' put a damper in it.

 

[Highbeam]

I'm very occasionally getting backdraft problems via my vent for my bathroom (ceiling fan) and perhaps the vent for the shower/sink. I believe the shower and sink plumbing is vented by code to a small 3" (guestimate) pipe that just barely sticks above my roof. The bathroom fan is vented to a louvred square vent too.

If I'm getting smoke occasionally coming through the small 3" pipe, what is the standard way to prevent this? Some kind of directional piping to point the tube away from my chimney or to raise it higher than the flue for my stove?

Jay

You say the smoke is coming down the small 3" pipe which you describe as the plumbing vent. But it sounds more likely that you meant the smoke is coming back in through the square vent which is the exhaust for your fans right? There is supposed to be a flapper in that roof vent that acts as a check valve to only allow air to be forced outwards. The flapper can be plugged up with lint and junk and blocked open. Clean it out. Often times there is an additional flapper on the fan unit itself which can also be gummed up and stuck open. Normally I would think hot air would want to rise out of the open vent pipe but if conditions are right air might blow down too.

I don't think it is the suck being put on your home by the stove that is the culprit.

 

[Michael6268]

You shouldnt be getting anything down the plumbing vent pipe and into the house. The "traps" would prevent that.

 

[webbie]

More likely it is coming in through soffit vents and other such places and then small cracks or open windows. It is possible for some to come in through bath or kitchen vents.

Mich is right about traps - there is a solid wall of water in between vents and your home.