Use and Care Manual

20
6-560.8
CONTROL OPERATING SEQUENCE / UNIT COMPONENTS
Upon a call for heat from the thermostat, power is supplied to
the power exhauster motor. The unit will go through a purge
period and then the direct spark igniter will be energized. At the
same time, the main valve in the combination control valve will
open to allow gas to flow to the burners. If the fan motor has
not already started it will start shortly. If a flame is not sensed
within 7 seconds for any reason the main valve will close and
there will be a short purge period before ignition is tried again.
If the flame is not sensed after four tries there will be at least a
one hour wait before ignition is tried again.
CONTROL OPERATING SEQUENCE
Figure 20.1 - Major Gas, Electrical Service, Safety and Other
Components
1. Power Exhauster
2. Pressure Switch
3. Integrated Direct Spark
Control Board
4. Combination Gas Control
5. Control Transformer
5
2
1
4
3
7
8
8
6
9
10
6. Flame Sensor (hidden)
7. Auto Reset Limit Control (hidden)
8. Direct Spark Igniter (hidden)
9. Gas Pipe Connection
10.HorizontalAirDeectorBlades
Table 20.2 - Gas Controls - All Models
Control System Description
Gas
Type
Control
Code
Control
Voltage
Service
Voltage
Single-Stage, Direct Spark Ignition,
100% Shut-off with
Continuous Retry
Utilizes a single-stage
combination gas control with
ignition control.
Gas is lit with a direct spark
igniter on call for heat.
Natural 11
24V 115V
Propane 21
Two-Stage, Direct Spark Ignition,
100% Shut-off with
Continuous Retry
Utilizes a two-stage combination
gas control with built-in ignition
control. Firing rate is 100% and
50% of full rated input. Gas is lit
with a direct spark igniter on call
for heat.
Natural 12
Propane 22