Sewer Gas when furnace is on

cindys0417il · Sat Feb 23, 2008 11:46 am

I smell sewer gas when the furnace is on. Would it help to have the heat vents cleaned? Could this have to do with it being really cold in Illinois and maybe the vent on the roof is not open? I don't know much about the sewer gas vent and how can I tell which one it is on the roof? (sorry for such a stupid question) I notice this smell sometimes in the summertime too when my air is on too so not sure its really the vent...Help!

Greg · Sat Feb 23, 2008 3:19 pm

Cindy, this is not a stupid question. I mist admit that I am baffled by it though.
If you are sure that it is indeed sewer that you are smelling, I would say you need to find out where the heat ducts are picking it up. You will need to start in the "basement", Check under your home for any obvious leaks. Look for water or ice coming from the belly. It is possible that you have a drain line leaking and somehow getting into the heat duct. You may be able to use a mirror and flashlight to see down the duct through the register from the top also. Greg

Steve S. · Sat Feb 23, 2008 8:51 pm

Do you smell sewer gas coming from the floor registers? That would be odd

...I'm thinking that perhaps there is a p-trap(s) that may be void of water and the negative pressure created by the furnace sucking air from the house is pulling sewer gases through the drain pipes, hence the odor. Check your drain vents for blockage and like Greg says, check for leaks down under. Some furnaces pull air in from underneath also.

Sat Feb 23, 2008 10:29 pm

I bet the sewer gas smell is coming from the roof. Unless you have an older home, on top of most roofs is a vent that brings fresh air into the home when the furnace is running. I bet you have a sewer vent near that vent. When the furnace is running, it's pulling sewer gases from that vent, through the fresh-air vent and into the home.

To minimize the problem, extend the sewer vent up past the fresh-air vent. To extend the pipe, just add a coupler and another piece of pipe.

Let us know how it comes out.

Mark

cindys0417il · Sun Feb 24, 2008 4:59 am

Thanks Mark..I will try that...I was thinking it might have something to do with the sewer vent on the roof....It has been really cold here in Illinois too and maybe there is ice blocking the air flow...thanks for the suggestion...I'll have to send my son up there and look at it...thats a good suggestion about adding a piece of pipe to the vent. thanks!