18 | Condensate Drain
A drain line must be connected to the heat pump
and pitched away from the unit a minimum of 1/8"
per foot to allow the condensate to flow away from
This connection must be in conformance with local
plumbing codes. A trap must be installed in the
condensate line to ensure free condensate flow.
A vertical air vent is sometimes required to avoid
air pockets. The length of the trap depends on the
amount of positive or negative pressure that is on
the drain pan. A second trap must not be included.
(See Fig. 49.)
A supply air outlet collar and return air duct flanges
are provided on all units to facilitate duct
Supply air duct and return air duct flanges are
shipped unfolded with the unit. They need to be
folded. See "Return and Discharge Air Duct
Flanges" on page #14 for details.
Refer to unit Dimensional Drawings for physical
dimensions of the collar and flange. (See page #63
through page #65.)
A flexible connector is recommended for supply
and return air duct connections on metal duct
systems. All metal ducting should be insulated
with a minimum of 1-inch duct insulation to avoid
heat loss or gain and prevent condensate forming
during the cooling operation. Application of the
unit to uninsulated duct work is not recommended
as the unit's performance will be adversely
NOTICE: Do not connect discharge ducts
directly to the blower outlet.
The factory-provided air filter must be removed
when using a filter back return air grill. The factory
filter should be left in place on a free return
If the unit will be installed in a new installation that
includes new duct work, the installation should be
designed using current ASHRAE procedures for
duct sizing. If the unit is to be connected to
existing duct work, a check should be made to
ensure that the duct system has the capacity to
handle the air required for the unit's application. If
the duct system is too small, larger duct work
should be installed. Check for any leaks in the
existing duct work and repair as needed.
The duct system and all diffusers should be sized
to handle the designed air flow quietly. To
maximize sound attenuation of the unit blower, the
supply and return air plenums should be insulated.
There should be no direct straight air path through
the return air grille into the heat pump. The return
air inlet to the heat pump must have at least one 90
degree turn away from the space return air grill. If
air noise or excessive air flow are a problem, the
blower speed can be changed to a lower speed to
reduce air flow.
Supply and return piping must be as large as the
unit connections on the heat pump (larger on long
Flexible hoses should be used between the unit
and the rigid system to avoid possible vibration.
NOTICE: Never use flexible hoses of a
smaller inside diameter than that of the
fluid connections on the unit.
Ball valves should be installed in the supply and
return lines for unit isolation and unit water flow
SM units are supplied with either a copper or
optional cupro-nickel condenser. Copper is
adequate for ground water that is not high in
Subject to change without prior notice
Greensource CDi Series SM
Greensource CDi Series SM Model