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

Condensate Drain Connection

Alan (California Radiant) Forbes
Alan (California Radiant) Forbes Member Posts: 2,965
edited November 2020 in THE MAIN WALL
Connecting the boiler's condensate hose directly to the drain is something I see a lot and over time, it causes problems. If the drain gets clogged or if the neutralizer isn't changed often, water can back up and create misfirings in the combustion chamber.
There should be some kind of air gap so that if the drain backs up, it overflows onto the floor instead of backing up into the boiler. Eventually, someone will notice all the water on the floor and will clear the drain.
We install a 3/4" x 1-1/2" increaser at the boiler end and drop the drain hose into it.

Often wrong, never in doubt.


  • kcopp
    kcopp Member Posts: 3,815
    I especially see this when they are hose clamped directly to a condensate neutralizer.
  • Jamie Hall
    Jamie Hall Member Posts: 17,025
    In my humble opinion, there must be an air gap -- and a trap. Did I miss something?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England