HELP PLEASE...sewer/rotten egg smell from vents

[fanny c]

If anyone could offer some insight, I would be so grateful. For several months now, whenever air is blowing through the vents, there is an intermittent rotten egg/sewage smell that comes out the vents and lasts about 10 minutes. It comes and goes a few times a day without any regular interval. I've had countless HVAC and AC guys out to look and all they ever want to do (or maybe all they know) is clean out the AC unit and the coils. The unit is fairly new and I've already had it cleaned. But that's all they can come up with and most people I've called have NEVER heard of something like this. Any of you out there ever experienced this? I'm having my first baby soon and can't stand that she'll have to breathe this in. Thank you so much.

[HayZee518]

maybe something like a mouse is dead inside one of your trunk lines. other possibility is the warm air return is near a toilet or a sink trap that is dry.

[manhattan42]

Not The HVAC

The problem is not with the HVAC but with the plumbing pipes.

The HVAC when on can create a negative pressure that can gas from an open or leaking plumbing trap or vent.

A plumber can check your plumbing system with smoke to determine where the problem is originating, then repair it.

[fanny c]

Thanks so much for your reply. I am having someone come out Thursday to do a smoke test.

[Redwood]

Hi Fanny,
Sometimes a quick inspection of your plumbing often will yield the solution without going through the expense of a smoke test.

• unused fixtures with dry traps.
• loose or rocking toilets.
• improperly plumbed condensate drains from the hvac unit.

Are just a few of the things that should be looked at.

[HandymanCincy]

Don't forget a clogged or capped plumbing vent stack. Move into a new home once and had the exact same problem problem you describe. Hopped up on the roof and discovered that the plumber never busted off the vent caps after his pressure test.