Condensing PDV Series
9
Sequence of
Operation
Power Up Sequence
1. Start Up:
Upon power up, the control runs a safe-start check with a typical start-up delay of 5
seconds.
2. Flammable Vapor:
To assure no outputs are energized if the Simulated Resistive Device is out of
range, the control will test the Simulated Resistive Device for proper operating
range. If Simulated Resistive Device is out of range, the control LED immediately
flashes 7 times with a 3 second pause.
Normal Heating Sequence
1. Thermostat Calls For Heat:
Prior to energizing the blower, the gas control checks the safety circuit to ensure
that the circuit is open. Normal switch positions in the safety circuit are as follows:
a) Exhaust pressure switch normally open.
b) Intake pressure switch normally closed.
c) Blower temperature switch normally closed.
If the safety circuit is closed, the control waits 4 seconds, then the gas
control LED flashes 2 times with a 3 second pause. The gas control waits 2
minutes and then the blower runs for 30 seconds. This cycle repeats until the
safety circuit opens.
2. Blower energizes.
3. Pressure Switch Proves Blower/Vent System Operation:
If both pressure switches are not closed within 30 seconds, the control LED flashes
3 times with 3 second pause. The blower runs for 30 seconds every 2 minutes
trying to get the both pressure switches and temperature switch into a closed state.
This cycle repeats as long as there is a call for heat.
4. Blower pre-purge period (2 seconds).
5. Trial For Pilot Ignition (90 seconds):
a. The gas control lights the pilot by activating the spark igniter and gas flow to
the pilot burner.
b. If the flame is not sensed within 90 seconds, the igniter and gas flow are
deactivated, the blower will post purge and the control LED will flash 6 times
with a 3 second pause.
6. Main Burner Ignition:
After the pilot flame is sensed, the gas control activates the main valve for main
burner ignition. The gas control will ignore the flame and pressure switch signals for
3 seconds allowing for the main burner to stabilize.
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