Why did sewer gas smell disappear after using central air?

Question

We have had a sewer gas smell in basement that circulates throughout entire house through the air returns. This has been going on for at least three years This year it was unbearable. Every time we did laundry the entire house stunk. I have had 2 plumbers come and they could not figure it out. We have made holes in walls looking for holes in vent pipes. Flushed vent pipes. Done pepermint test etc. Then the heat wave came and we turned on the central air. NO SEWER GAS SMELL! We are doing loads and loads of laundry and no smell anywhere in the house. We keep the air on because this prevents the smell. Does anyone understand what is going on here? I do not want to spend any more money for confused plumbers.

Answer 1

More air you add the less smell, the chemicals are still in the air you have just mixed in more air so it is not so dominate of a smell. Others coming  into your home may smell it though.....

I saw in the news in Portland Oregon where the city sewer system was so old that  fumes were leaking into peoples homes. It was not the home owners but the city who has to clean it up and help the people clean there places up. This was in the news not long ago. I think the sewer finally gave out and flooded peoples basements. Probably still on the web somewhere, maybe this is your problem?

Answer 2

I would guess that your condesation drain from your A-coil in your furnace is tied somehow into a sewer drain line. When the a/c isn't used the condesation trap water evaporates allowing that sewer gas to follow the plastic pipe up and through the dried out trap and out into the air around your furnace.

When you start running the ac, that condesation trap then fills up with condesation from the a-coil dripping into the pan and filling up the trap. This then blocks the sewer smell as there is now some water in the trap.

Look on your furnace for a small 3/4" or 1"  PVC fitting coming out under where the air conditioning coil is. Follow it to find if it goes into sewer or perhaps a floor drain. If it is going to a floor drain, the same thing could be happening- the water in the floor drain trap has evaporated away until you start the ac, then the condesation fills up the floor drain trap and VUALLA!!!!!!! sewer smell stops because the trap now has some water in it.

Answer 3

Are you sure there isn't something rotting in your a.c.? LOL. Well if the air is turned on and the smell is gone, it's going to be hard to detect where the smell is coming from, now isn't it! I think you should call up the AC company who services your parts/ system and ask them for advice. I never had this situation happen, but it sounds like you should have your sewer lines inspected. Do you own a septic tank or is it done by the city? Maybe your tank needs an emptying!  I would be very grossed out if we kept smellilng sewage... I say call up whoever is local and services the AC, sewer, and have another plumber come (one who is very reputable) and take a look at it. I also wonder if it has to do with your washing machine and the waste water... WHO KNOWS!

Answer 4

Is there a drain in the floor somewhere?  If there is, dump a cup of water in it.  There is a trap in there that holds water so the sewer gas doesn't come up.

Answer 5

Basements have no windows and no way for air to circulate.

I use to take care of rentals.  They closed up the windows and turned up the heat.  Mold would grow on the walls on every floor, worse in the basement.

I told them to turn on the ceiling fan in the bathroom and leave it on.

We scrubbed down the walls with clorox bleech to remove the mold and kill it.  Opened the windows and turned on fans.

Didn't know what we was going to do the house was so bad.

A carpender came out and put in around the outside edge air vents.  So air circulation could happen under the house.

Then when renting it again asked the potential renter do you like to sleep with windows open?  She said, "yes she did"

After they moved in and kept the ceiling fan on and windows opened it never had a mold problem again.

When she moved we sold the house.

But in having rentals found that some people by closing up the place make the house mold and stink.

We put in ceiling fans, air conditioners, bathroom ceiling fans.

That come on automatically when they turn on the light.