Replies

1. GBA Editor
   Martin Holladay|Mar 07, 2018 11:54am|#1

   Anthony,
   (1) You can install a trap in the drain line. Pour some mineral oil in the trap to create an air seal. (Mineral oil evaporates more slowly than water.)

   (2) Get a condensate pump and route the drain line to a nearby laundry sink. (This works if the sink drain has a trap and if the sink is used regularly enough to keep the trap from evaporating.)

2. Expert Member
   MALCOLM TAYLOR|Mar 07, 2018 12:06pm|#2

   Anthony,

   Are you sure the trap just hadn't been filled? Our code mandates traps on all interior drains. As Martin said, they can dry out, but mineral oil stops that.

3. 
   Remodelpro|Mar 07, 2018 12:32pm|#3

   Thanks Martin and Malcom,

   Typically overflow pan drains must be routed to the exterior of the building (Daylight) and most inspectors do not allow them to be trapped.. Any other suggestions?

4. Expert Member
   MALCOLM TAYLOR|Mar 07, 2018 12:45pm|#4

   Anthony,

   There is manufacturer that makes back-flow valve drains that also are very air-tight. Unfortunately I can't remember the name - but I'm pretty sure it has come up here on GBA. Perhaps another poster can remember it.

   Edit: The reason I said A manufacturer is that a lot of the back-flow values work by closing the drain with a float when water comes up from below. The one I'm thinking of works similarly to an air admittance valve, using a spring. So it is always closed unless there is water from above.

5. Expert Member
   MALCOLM TAYLOR|Mar 07, 2018 12:54pm|#5

   Another option to get around the inspector's allergy to traps is to terminate the pan-drain near a floor drain (which presumably has a trap). This is allowed in the 2015 IPC.

6. 
   Remodelpro|Mar 07, 2018 02:39pm|#6

   Thanks Malcolm,

   I believe that this is the back flow valve you are referring to.
   https://www.rectorseal.com/waterless-kits/
   I believe that this solution will make everyone happy.

7. GBA Editor
   Martin Holladay|Mar 07, 2018 02:42pm|#7

   Anthony,
   Thanks for the link.

8. Expert Member
   MALCOLM TAYLOR|Mar 07, 2018 03:16pm|#8

   Anthony,
   Yes, that's the one. These type of problems are annoying to deal with. When each jurisdiction has different standards, you realize how arbitrary they are.