Hi,

We are getting a rotten egg smell coming from our house vents. Does not occur all of the time. We have a heat pump and does not occur during the colder months. Mainly occurs when it is hot and the AC is running.

Had the heat pump coils cleaned.

Any other suggestions other than getting the vents cleaned?

Any ideas what would be causing it (but not every time the AC is running)?

Thanks.

Paul

Sounds like the house might be under negative pressure and it is allowing the odor from a bad plumbing vent to be sucked into the system.

Is your condensate drain piped into the house plumbing system or does it go directly outside? Is there a condensate trap? Where is your air handler unit, in your attic or basement. Are the covers and filter doors closed and are all the screws back in the holes. Are there any gaps in your return air ducts that can be sucking in air?

Slab foundation? Is ground water seeping up into the ductwork or plenum in the springtime rains?

If your house is under negative pressure and is sucking in air from a plumbing vent, how would you go about resolving this?

I don't believe most homes are under a negative pressure. Unless you are running an exhaust fan that's discharging a lot of cfm, it takes a real well sealed home to create a negative pressure. Usually there are vents in your attic that allow air movement in the attic and air can usually get in your home through door cracks, vents, windows etc. There are units you can purchase ( Energy Recovery Units ) that will allow you to bring in fresh air that it will transfer the moisture /heat back outside. You can always crack a window (open it some) to prevent the negative pressure. Your plumbing system should have traps that will prevent any sewer gases from getting into your home. Sometimes they will dry out and you may have to run some water in any unused drains to keep the water level up.