Exhaust Pressure Switch Testing And Replacement - Bradford White EF Series Service Manual

Sequence of operation:
Sequence of operation:
With the thermostat calling for heat, prior to energizing blower, the ignition module checks the exhaust pressure switch for normal
With the thermostat calling for heat, prior to energizing blower, the ignition module checks the exhaust pressure switch for normal
switch position of normally open. If the exhaust pressure switch contacts are closed (not in normal position), the ignition module
switch position of normally open. If the exhaust pressure switch contacts are closed (not in normal position), the ignition module
waits 45 seconds for the pressure switch contacts to open. If the pressure switch contacts do not open after 45 seconds, the
waits 45 seconds for the pressure switch contacts to open. If the pressure switch contacts do not open after 45 seconds, the
ignition module locks out with the PURGE LED flashing indicating a pressure switch fault.
ignition module locks out with the PURGE LED flashing indicating a pressure switch fault.
LED Status
LED Status
Only power LED is on, or
Only power LED is on, or
Purge LED flashing.
Purge LED flashing.
Does blower N
Does blower
N
energize?
energize?
Y
Y
Call technical
Call technical
support.
support.
Does heater
Does heater
function?
function?
Verify proper
switch operation.
Verify proper
(see pg 38)
switch operation.
(see pg 38)
Check PURGE LED status
on ignition module, is LED
Check PURGE LED status.
off then Flashing after 5
minutes?
Y
On within 5 minutes?
Check amp draw through
N
BLACK wire lead of blower
N
motor. Is there .6 to 1
amp?
Flashing after
N
5 minutes?
Y
Y
Is Blower wheel secured to N
blower motor shaft?
Check blower for proper
N
operation (see page 25)
Is blower OK?
Y
Y
Refer to
"Check Collector Pressure"
Refer to
(see Pg 28)
"Check Collector Pressure"
(see Pg 28)
Service Procedure EF-VI
Service Procedure EF-VI

Exhaust Pressure Switch Testing and Replacement

Exhaust Pressure Switch Testing and Replacement
Safety Circuit Trace
Safety Circuit Trace
Is there continuity
Is there continuity
Through GREY
Through GREY
wire leads of heater side
wire lead of heater side
safety circuit harness?
safety circuit harness?
(see photo 20)
(see photo 20)
N
N
Depress reset
Depress reset
button on vent
N
button on vent
safety switch. Is
N
Y
safety switch. Is
there continuity
Y
there continuity
across high limit
Y
across high limit switch?
Y
(see photo 21) switch?
(see photo 21)
N
N
Replace vent
safety switch.
Replace vent
(see pg 39)
safety switch.
(see pg 39)
Pressure switch is OK.
Replace blower.
(see pg 26)
Call for technical
support.
Correct blower problem
(see page 25)
WARNING
WARNING
120 volt potential exposure. Use caution
120 volt potential exposure. Use caution
making voltage checks to avoid personal injury.
making voltage checks to avoid personal injury.
Is there continuity
Is there continuity
through RED
Y
through RED
Y wire leads of heater side
Lead wires of heater side
safety circuit harness?
safety circuit harness?
(see photo 20)
(see photo 20)
Y
Y
Check PURGE LED status
Check PURGE LED status
on ignition module,
on ignition module,
Flashing after 45 seconds?
Flashing after 45 seconds?
Control side
Control side harness
harness
Reset button
Reset button
Safety Circuit OK,
N
Safety Circuit OK,
N See Blower.
See Blower.
(Page 25)
(Page 25)
Replace exhaust
Replace exhaust
pressure switch
pressure switch
(see Pg 29)
(see Pg 29)
Heater side
Heater side harness
20
harness
20
21
21
Page 27
Page 27
Page 27