Installation and Service Manual

18
6-584.13
Figure 18.2 - Unit Heater Rear View
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 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 4 tries there will be at least a one hour wait before
ignition is tried again.
CONTROL OPERATING SEQUENCE
Figure 18.1 - 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
6. Flame Sensor (hidden)
7. Flame Rollout Switch
8. Auto Reset Limit Control (hidden)
9. Direct Spark Igniter (hidden)
10. Manual Reset Control (hidden,
propeller 100-125 only)
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Vent Pipe Connection
Gas Pipe
Access Panel with
Lighting / Operating
Instructions
Electrical Access
Holes
Fingerproof Fanguard
Fan Motor
Mounting Brackets
Table 18.1 - Control Options
Control Description
Control Service Thermostat Type of Model
Code No. Voltage Voltage Gas Size
Single-Stage, Direct Spark Ignition, 100% Shut-Off with Continuous Retry 11 115V 24V natural 30-125
- Utilizes a single-stage combination gas control with ignition control.
Gas is lit with a direct spark igniter on call for heat. 21 115V 24V propane 30-125
Two-Stage, Direct Spark Ignition, 100% Shut-Off with Continuous Retry 12 115V 24V natural 75-125
- 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
22 115V 24V propane 75-125
igniter on call for heat.
Combustion Air Inlet
Pipe Connection
Flame
Sight Glass