Safety Circuit Voltage Trace - Bradford White UPV Series Service Manual

UPV Service Procedure IX – Safety Circuit Voltage Trace

Safety Circuit Voltage Trace

NOTE: This procedure assumes a cool tank.
Remove three screws (T20 Torx screwdriver) from control
access cover on blower and remove cover (see photo 20).
Position gas control switch on the "ON" position
and adjust thermostat dial to call for heat. Is
there 10 to 13 VAC between switch and jacket
head screw shown in photo 21? Blower must
be running during this voltage check.
Y
Is there 10 to 13 VAC between
red wire on temp switch and
jacket head screw?
Y
Do you hear or
can you see the
igniter sparking?
Y
Safety circuit
voltage is OK.
21
Is LED on gas valve
N
flashing the "heartbeat"
Verify 115VAC to gas
control (see page 30).
Is there continuity through blower
N
temperature switch? (see page 23).
Check igniter/sensor
N
(see page 16).
Is igniter/sensor OK?
If burner does not light, observe LED
flash code on gas valve and refer to
troubleshooting section on page 12.
WARNING
115 volt potential exposure.
Use caution to avoid personal injury.
Y
code (alternating
bright/dim).
N
Y
N
Correct igniter/sensor problem.
Y
Faulty cord set or gas control.
20
Blue wire leading to
blower temp. switch
Red wire leading from
pressure switch
Jacket head screw
29
No voltage from gas control,
call Technical Support.
Check for loose or
broken wire connection
at switch terminals.
Determine case of blower
temperature switch
N
activation and correct.
29