20
Note: Low Ambient Operation
Air-cooled DX units without a low ambient
option, such as condenser fan cycling or the
0°F low ambient option, will not operate in
the cooling mode of operation properly when
the outdoor temperature is below 55°F. Low
ambient and/or economizer options are
recommended if cooling operation below
55°F is expected.
Gas or Electric Heating
The unit is designed to heat a given amount
of air while operating. If this amount of air is
greatly reduced, approximately 1/3 during
the heating season, the gas heat exchanger or
electric heating coil may overheat, and may
cut the burner or heater off entirely by action
of the safety high temperature limit devices
which are factory mounted at the heat
exchanger and supply fan areas.
Airflow should be adjusted after installation
to obtain an air temperature rise within the
range specified on the unit rating plate at the
required external static pressure.
Should overheating occur with a gas heat
exchanger, or the gas supply fail to shut off,
shut off the manual gas valve to the furnace
before shutting off the electrical supply.
Prolonged overheating of the heat exchanger
will shorten its life.
The maximum supply air temperature from
the gas heater is 140
°
F and the minimum
allowable entering air temperature is 40
°
F.
The maximum temperature rise for the gas
heater is 100
°
F.
Wiring Diagrams
Unit specific wiring diagrams are laminated
and affixed inside the controls compartment
door.
Condensate Drain Pans
Units require field installed drain p-traps and
lines to be connected to the condensate drain
pans of the unit.
For condensate drain lines, the line should be
the same pipe size or larger than the drain
connection, include a p-trap, and pitch
downward toward drain. An air break should
be used with long runs of condensate lines.
See Installation section of this manual for
more information.
Unit should not be operated without a
p-trap. Failure to install a p-trap may
result in overflow of condensate
water.
CAUTION
Emergency
drain
pan
is
recommended for all applications
where a risk of water damage to
surrounding structure or furnishings.
Refer to local codes.
CAUTION
