Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Foul Odor

It smells like something died in my house, but I am suspicious that it may be problems with my heat/AC system.

I have a hydronic heat boiler running into an air handler the does both heat & A/C into what used to be a conventional scorched hot air system. I replaced the old furnace with the boiler with hopes of doing in floor radiant heat at some point in the future. I have had problems with the A/C condensate overflowing the pan in the air handler and ending up on the floor, soaking the rug on the lower (partly finished) level of the condo. I had my contractor replumb the 1" condensate line that empties into an ejector pump to create a steeper incline to insure better drainage. In doing so they bypassed the existing P trap, capped it, and tied the condensate line into the ejector tank inlet at a lower level. The condensate line is now a straight shot with no trap. It would look to me like the negative air pressure in the air handler is drawing sewer gas up the condensate line and into the duct work where it is distributing it about the house. Some areas smell more, where I assume the gas settles when not being blown about by the fan. Will a simple P trap solve this issue? Do I need a new heating contractor?


  • Ric Murray
    Ric Murray Member Posts: 23
    wrong pipe size

    In the above post I stated that the condensate pipe was 1". It is actually 3/4".
  • BillW
    BillW Member Posts: 198
    Foul odor

    You may have a couple different issues here.  Evaporator (cooling) coils get wet, and if condensate doesn't drain properly, it can lead to mold or algae growing either on the coil and/or in the condensate pan. Its usually described as a "dirty sock" odor.  If your condensate line is going directly into a sanitary sewer, that's downright dangerous.  Hydrogen sulfide is very poisonous, and tends to numb your smell receptors, so you may not smell it after while, but if in a high enough concentration, it will kill you.  It is also very corrosive, and will rapidly destroy metals of all kinds.  Methane also is a component of sewer gas, and is highly flammable, and explosive in the proper mixtures, with any ignition source.  Pipe your condensate to a sump pump pit, or outside.  A basic condensate pump is all you need. 

    Also, if you are using an hydronic coil for heat, it may give off an odor as it heats up, from dust and other debris on it.  It should decrease over time, and check for possible leaks.  Boiler water can be pretty smelly.
  • rockhound57
    rockhound57 Member Posts: 14
    ejector pump clarification

    you described the pump as an ejector pump, is it a small pump in a box about the size of a shoe box? that's typically a condensate pump, the correct type for the job. It should then pump to a trapped drain connection on the sanitary sewer. If it's going into a larger pump tank like a 5gal. pail or bigger, that's an official ejector pump, NOT the right application unless the connection is indirectly connected to a p-trap at the tank. Billw is correct, it is very unhealthy at best. Somewhere in the line, there needs to be an indirect connection before a trap, best located as close to the sewer as possible
This discussion has been closed.