Draining Condensate from Return-side Duct
Draining Condensate from Return-side Duct
(OP)
Hello, we've got an air cooler that consists of a cold water coil and a blower. The only place we can locate the coil is upstream (return, or suction side) of the fan, so I'm a bit concerned about corrosion if condensation droplets reach the fan. But my first concern is draining the condensate from the ductwork at the coil - what kind a trap would allow the condensate to drain out against the negative pressure differential? Thanks for any ideas.
Fran McConville
author of the Pilot Plant Real Book
www.pprbook.com





RE: Draining Condensate from Return-side Duct
If you maintain a coil face velocity below 500fpm, moisture carryover is minimum.
Regards,
RE: Draining Condensate from Return-side Duct
HVAC68
RE: Draining Condensate from Return-side Duct
Fran McConville
author of the Pilot Plant Real Book
www.pprbook.com
RE: Draining Condensate from Return-side Duct
You can use 2 to 3" difference for a seal.
Regards,
RE: Draining Condensate from Return-side Duct
Fran McConville
author of the Pilot Plant Real Book
www.pprbook.com
RE: Draining Condensate from Return-side Duct
RE: Draining Condensate from Return-side Duct
If you have about 24" between the condensate drain and the fan, that will be 0.067 in in pressure drop.
RE: Draining Condensate from Return-side Duct
Fran McConville
author of the Pilot Plant Real Book
www.pprbook.com
RE: Draining Condensate from Return-side Duct
Regards,
RE: Draining Condensate from Return-side Duct
Now, when the damper is closed, the air handler shouldn't be working. Additionally, if the damper is closed because of a fire, what importance may have a few drops of water into the AC ductwork anyhow? I don't think you should desing the P-trap for that condition.
Regards,
PS: Regarding pressure drops, CFM and duct sizing, get yourself a ductulator from Trane or other manufacturer. Call your Trane dealer, they will probably give it to you for free, or charge like 5 or 6 bucks.