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18-CD37D1-2-EN
Installer’s Guide
IMPORTANT:
The condensate drain should be installed with
provisions to prevent winter freeze-up of the condensate drain
line. Frozen condensate will block drains, resulting in furnace
shutdown. If the drain line cannot be installed in a conditioned
space and/ or its surrounding ambient temperature is expected
to fall below freezing, then heat tape should be applied as
required to prevent freezing (per manufacturer’s instructions).
The heat tape should be rated at 5 or 6 watts per foot at 120
volts. Self-regulating (preferred) or thermostatically controlled
heat tape is required.
Typical sources of UL listed heat tapes are W.W. Granger,
Inc. (Wintergard Plus
TM
Series), McMaster Carr Supply Co.
(3554 Series), or your equipment supplier.
The condensate drain may be cleaned or inspected by re-
moval of the drain tube at the header.
Evaporator and Furnace condensate drain piping may be
manifolded together as shown in Figure 46. A primary drain
vent stack must be installed and terminated below the outlet
of the secondary heat exchanger drain connection to prevent
water from damaging Furnace controls if the primary drain
outlet plugs up.
Where the Furnace is installed above a finished ceiling,
the primary drain vent stack must be installed such that
overflow from the vent stack opening will flow into an
auxiliary drain pan in order to prevent water damage to
the finished ceiling below.
ALL HORIZONTAL APPLICATIONS
ARE LEFT SIDE DRAIN ONLY
TO
OPEN/
VENTED
DRAIN
UPFLOW FURNACE ON LEFT SIDE
WITH LEFT DRAIN SHOWN
HEADER
Figure 45
Primary drain vent
stack must terminate
below secondary heat
exchanger condensate
drain outlet.
To drain opening
If upflow furnace is
installed over a finished
ceiling, overflow from
the primary drain vent
stack must flow into an
auxillary drain pan to
prevent damage to the
finished ceiling below.
Figure 46
