Bradford White EF Series Service Manual page 9

Lockout Conditions
The system will go into lock out mode for the following reasons:
-Pressure switches stuck open or closed.
a) Check for exhaust or intake obstructions.
b) Check for compliance with vent tables.
c) Check for evidence of moisture or condensate present in pressure switch tubing or pressure switch.
-No ignition after 3 attempts.
A) Check gas pressures.
b) Igniter resistance too high (lower resistance preferred <150 Ohms).
C) Check venturi screw adjustment (6 ½ turns from bottom)
d) Flame sense micro amp not present (1 to 5 micro amps required).
Lock out reset is accomplished by shutting OFF the line voltage to the system or opening the 24V thermostat
circuit for at least 2 seconds.
System will automatically reset lockout after 1 hour of continuous call for heat from the thermostat. Three ignition
trials will be attempted each hour until the thermostat is satisfied.
Ignition Module Specifications
Control Functions:
- Ignition & heating functions in response to thermostat.
- Hot surface ignition using a microprocessor to control timing, flame sensing using flame rectification & ignition
retries.
- Monitoring of system pressure switches and limit switches.
- Control of gas valve, inducer motor, and hot surface igniter element based on thermostat demand and status of
safety inputs.
- Diagnostic indicators to provide information on power to control and control status.
- Non-interchangeable polarized plug-in connectors for all interconnections.
Control Inputs:
- Thermostat call for heat.
- Limit Switch Circuit (normally closed)
- Pressure Switch Circuit (normally open)
- Flame sensing.
- Low voltage supply.
- Line voltage supply.
IGNITION MODULE
Sequence of Operation
Control Outputs:
- Inducer motor
- Hot surface igniter
- Gas valve
- Status indicator LEDs
Power - Green
Purge - Red
Igniter - Red
Valve - Red
Flame - Red
WIRING DIAGRAM
Page 9
Page 9