Is a trap required when useing condensate pump?

[CAE16]

When draining condensate from a cooling coil and utilizing a condensate pump; do you still need to trap the drain or is the trap function taken care of by the condensate pump?

 

[MintJulep]

If the discharge of the line from the coil drain pan to the pump's sump is always below the water level in the pump, and the depth of water in the sump is sufficient, then technically that will work as a trap.

Codes, and code enforcement officials may take a different view.

 

[CAE16]

Thanks, thats what i thought, problem is we are responding to a code officials request to provide a detail section of the condensate pump and piping arrangement.

 

[cjw81]

You should show at least a 2" air gap to prevent any back siphoning from condensate to drain. If you are using probes to turn the pump on and off, make sure you keep them clean as shorted probes will keep the pump on and cause a lot of replacements. There are plenty of biocide treatment tabs on the market.

 

[ChasBean1]

Condensate pump or not, here's how to think of it: you don't want a poor drainage setup that maintains a level of water in the coil drain pan that could be capable of microbial growth and release of contaminants into the airstream.

If you have a cooling coil on the fan suction side, the difference in height between the trap inlet (at the immediate cooling coil drain) to outlet, where the pipe discharges to whatever kind of drain you provide, should be equal to the fan suction pressure plus a filter loading margin.

For example, a fan normally operating at -2 in. w.c. suction should have a trap with an inlet-to-outlet of at least -3 in. w.c. The trap also needs to drop a sufficient level below both points to maintain a liquid level and prevent gurgling and back splatter. I'd suggest at least 1-2 in. below the trap outlet.

For a typical fan coil unit, if you pipe to a condensate drain sump, have the inlet pipe drop at least 4" out of the unit and drain a couple inches below the level of the water maintained in the sump. If the condensate sump doesn't provide piped inlet below the water line, use the afforementioned trap prior to the sump inlet.

 

[CAE16]

Thanks everbody.