Can the condensate from an air conditioning evaporator coil at an air handler in an attic drain into a vent pipe?
Wednesday, January 30, 2019
There are two reasons why the condensate drain from an air handler in the attic should not termate into a vent pipe nearby:
- It’s not allowed by the building code (Residential Edition of Florida Building code P3101.3 and similar in International Building Code).
- The blower in the air handler creates suction that can sometimes suck the water out of the trap and, even if that doesn’t happen, during the winter when the system is in heating mode, the trap will dry out anyway. This will allow sewer gas from the vent pipe to be pulled into the air flow at the air handler and be circulated throught the duct system in the home.
We saw the example shown above of a condensate drain into a nearby vent pipe recently in an empty house in Gainesville. It had been on the market for a while and, as soon as we tested the plumbing and ran the a/c, a sewer smell filled the house. So just don’t do it.
Also, see our blog posts Can an air conditioning condensate drain pipe connect to a sink drain? and Does code require a p-trap in an a/c condensate drain? and When is an auxiliary drain pan required under an air conditioner indoor unit (air handler)? and Should I move my air conditioner into the attic?
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To learn more about heating and air conditioning systems, see these other blog posts:
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