To prevent property damage due to fire and loss of
equipment efficiency or equipment damage due to dust
and lint build up on internal parts, never operate unit
without an air filter installed in the return air system.
Even though a return air filter is not supplied with this unit, there
must be a means of filtering all return air. All units may be
Refer to the unit filter size chart in the Appendix for filter size
Filters installed external to the unit should be sized in accordance
with their manufacturer recommendations. A throwaway filter
must be sized for a maximum face velocity of 300 ft per minute.
IMPORTANT: When installing a filter, the airflow arrows on the
filter must point toward the circulator blower.
Install the flue exhaust hood, screen and lower flue hood prior to
operation of the unit.
To install the flue hood cover, please refer to IO-653*, included in
the flue hood assembly box located in the blower compartment.
Flue Hood and Bug Screen Installation
A. Flue exhaust hood
C. Lower flue hood
D. Combustion air intake hood
E. Heat exchanger door
Condensate Drain Connection
A ³⁄₄" (1.9 cm) NPT drain connection is supplied for condensate
piping. An external trap must be installed for proper condensate
A. Drain connection
B. 2" (5.1 cm) minimum
C. 3" (7.6 cm) minimum
NORMAL SEQUENCES OF
This unit is equipped with an ignition control that automatically
lights the main burner.
NOTE: Do not attempt to light the main burners by any other
1. Thermostat calls for heat. The induced draft blower energizes
for a 15-second pre-purge.
2. The spark igniter and gas control valve energizes for
NOTE: The igniter produces a very intense electrical spark
that ignites the gas.
3. The 30-second Heat Fan On delay time begins.
4. The unit delivers heat to the conditioned space until the
thermostat is satisfied.
5. The gas control valve de-energizes. The induced draft blower
continues operation for a 29-second post-purge.
6. Ignition control begins timing the Heat Fan Off delay. There is
an adjustable Heat Fan Off delay of approximately 120/135/
150 seconds (factory-set at 150). After the Heat Fan Off delay
time has elapsed, the blower will de-energize. This allows any
additional heat in the heat exchanger to be transferred to the
D. Positive liquid seal (required)
E. Flexible tubing, hose or pipe