Unit Components - Modine Manufacturing PTX Installation And Service Manual

CONTROL OPERATING SEQUENCE / UNIT COMPONENTS
CONTROL OPERATING SEQUENCE
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
Figure 25.1 - Major Gas, Electrical Service, Safety and Other
Components
8
1
9
2
5
4
3
1. Power Exhauster
2. Pressure Switch
3. Integrated Direct Spark Control Board
4. Combination Gas Control
5. Control Transformer
Table 25.1 - Control Options
Control Description
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.
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.
6
8
7
6. Flame Sensor (hidden)
7. Direct Spark Igniter (hidden)
8. Auto Reset Limit Control (hidden)
9. Gas Pipe Connection
10. Horizontal Air Deflector Blades
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 4 tries there will be at least a
1 hour wait before ignition is tried again.
10
Control Service
Code No. Voltage
11 115V
21 115V
12 115V
22 115V
6-534.1
Thermostat Type of
Voltage Gas
24V natural
24V propane
24V natural
24V propane
25