Greenheck ERCH - Energy Recovery Unit with Packaged DX (468151) - Manual (Page 12)

12
Energy Recovery Unit with Packaged DX
DRAIN TRAP
Cooling coils are provided with a stainless steel drain pan
with 1-inch male NPT drain connection . A drain trap must be
connected to the drain connection to allow excess water to
flow out of the drain pan . More importantly, though, due to the
negative internal static of the cooling coil compartment, installing
the drain trap prevents outdoor air from being pulled into the
drain pan and consequently forcing water out of the pan and into
the unit .
To ensure the drain trap works properly, the trap height must
account for the difference in static pressure between ambient
conditions outside the unit and the internal negative pressure of the cooling coil compartment . For energy
recovery units, an assumption of 3 .0 in . wg differential will be sufficient . This would require a trap design as
shown . If the internal static is believed to be higher, consult factory .
Refer to local codes to determine drainage requirements . If draining onto to roof, place a drip pad below drain
to protect roof . If draining onto roof is not acceptable, a drain line must be attached to the trap . The drain line
must be pitched away from the unit at least 1/8-in . per foot . On longer runs, an air break should be used to
ensure proper drainage . Local codes may require drainage into a waste water system .
Drainage problems not only occur from improper drain trap design, but also from lack of maintenance of the
cooling coil compartment . Algae can form in the drain pan and trap and cause reduced water flow, which can in
turn result in backup into the system . Regular maintenance will prevent this from occurring . If the drains have a
cleanout opening, be sure to close the opening after cleaning .
4 in.
2 in.