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21. P40U-P (-IP), P40U-W (-IW) SEQUENCE OF OPERATION GASLITER 50N (DSI)
The Gasliter 50N is a three trial ignition control module with a 30 minute soft lockout/reset. It is
powered by a 24v transformer that is activated when the thermostat calls for heat. On every call
for heat the Gasliter 50N will delay start-up to provide a 30 second system pre-purge. When the
Gasliter 50N is activated by a thermostat or call for heat an internal transformer provides power
to the electronic generator circuit for Spark Ignition and the retrial/safety lockout timing begins.
At the same time, the Gasliter 50N opens the gas control valve allowing gas to flow to the main
Burner.
The Gasliter 50N Control Module performs the following basic functions:
·
Provides a 30 second system pre-purge
·
Supplies power to the electronic pulse-generator circuit for the Spark Igniter (30,000 volts
open circuit).
·
Allows up to three 20 second Trials For Ignition (TFI) before a 'soft' system safety lockout of
30 minutes occurs.
·
Three time TFI and soft 30 minute lockout repeat
·
Senses the Burner flame for safe lighting
·
Shuts off the spark after the Burner is lit.
Burner with direct spark ignition, sequence is as follows :
1a. Line Voltage Thermostat: Upon a call for heat by the line voltage Thermostat or "ON/OFF"
switch, the Blower and the 120/24 volt Transformer are powered simultaneously with 115
volts. .... continue to 2.
1b. 24 Volt Thermostat: 120 volt supply to heater powers the 120v/24v Transformer and the
120V side of the Blower switching relay simultaneously. A call for heat by the 24 volt Ther-
mostat energizes the 24 volt control circuit and the 24v/120 volt relay powering the Blower.
2. The 24 volt control circuit powers the DSI control in series through the normally open Air
Pressure Switch (APS) and the normally closed Blocked Flue Switch (BFS).
3. The Blower creates a positive pressure and closes a normally open contact inside the Air
Proving Switch (APS).
4. Provided there is no blockage in the system (tube and vent), the Blocked Flue Switch re-
mains in a normally closed position.
5. 24 volts supplied to the DSI control initiates the 30 second pre-purge cycle.
6. After completing the 30 second pre-purge cycle the DSI control generates high voltage to
the Spark Igniter, and 24 volts to energize the Gas Valve.
7. The Burner will light and establish a steady flame.
8. Once the flame sensor determines there is a steady flame established, with a minimum
flame signal of 1.5 µA the spark igniter is then de-energized.
9. In the event ignition does not occur, the DSI control will retry the ignition sequence up to an
additional two trials. If ignition does not occur after the third ignition trial, the system will en-
ter a 30 minute 'soft' lock-out. This will reset the ignition module and the operating se-
quence will restart at step #1 after the 30 minute lock-out period.
10. If there is a loss of flame during the run mode, the unit will energize the spark within 0.8
seconds and perform a T.F.I., without the gas valve being closed first, this is called Spark
Restoration. If a flame is not established during Spark Restoration the unit will repeat the
process in step number 9 (above).
31
P40U-F / P40U-IF I&O Manual
IM101220
RD: MAR 2014
RL: 4B
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