Propane or sewer smell

[Greg and Kathy]

It seems I get a stinky smell in my 5.0 and it seems to only be when using the furnace for a while. I notice it more when I stick my nose in the cupboard under the furnace. Soaped the line and fitting in the front of the furnace. I had enough wire to place my propane detector in the cupboard and is is not alarming. Any ideas.
I noticed it a few days ago and then it cleared as we were not running the furnace but today it was back as my furnace was running several times overnight.

[MVA]

Originally Posted by Greg and Kathy

It seems I get a stinky smell in my 5.0 and it seems to only be when using the furnace for a while. I notice it more when I stick my nose in the cupboard under the furnace. Soaped the line and fitting in the front of the furnace. I had enough wire to place my propane detector in the cupboard and is is not alarming. Any ideas.
I noticed it a few days ago and then it cleared as we were not running the furnace but today it was back as my furnace was running several times overnight.

Have you checked the air admittance valve to see if it is leaking? On our E19, it is in the furnace cabinet so if the furnace was running, air would be drawn next to the valve and pulling any fumes with it. Not sure where the valve is on the 5.0.

If you are not aware of what the valve looks like, an example is:
https://www.homedepot.com/p/Oatey-Su...9230/205395535

It allows air into the gray tank without the need for a vent stack.

[Greg and Kathy]

I was wondering why a black cap on the pipe in that cabinet. That May very well be the issue. Will check by unscrewing it and checking it out. How do you check to see if it’s stuck.

[Ron in BC]

You might be surprised to learn that in the good old days the vent in the 19 was in the closet and not capped at all.

Never bothered us but there were smell complaints from some folks.

Ron

[MVA]

Originally Posted by Greg and Kathy

I was wondering why a black cap on the pipe in that cabinet. That May very well be the issue. Will check by unscrewing it and checking it out. How do you check to see if it’s stuck.

It should be a one way valve; letting in air but not out. It may be attached with a threaded fitting. If not, you will have to cut the vent pipe in a way that it is easily reattached with a hub.

[Greg and Kathy]

It is screw on. I took a look at it and valve seemed loose and saggy. I will find a new one. It is screw on