Bradford White U-TW4-75S-76R-3N - Manual (Page 12)

Short flash, once every
four seconds
“Heartbeat”, alternates
bright/dim Thermostat calling
for heat (no fault).
Short flash once per
second Weak pilot signal
on last call for heat.
Two flash, three second
pause
Pressure switch not
working-closed
position.
Three flash, three second
pause
Pressure switch or
blower temp.
switch not working
-open position.
Four flash, three second
pause
Excessive tank
temperature.
System must be
reset.
Five flash, three second
pause Undesired-false
pilot flame present.
Troubleshooting
LED Status
Stand-by mode,
Waiting for call for
heat (no fault)
Control Status
Service
Procedure
Probable Cause
Temperature demand is satisfied.
Normal operation.
Adjust thermostat to
temp level.
Tank temperature below set point of thermostat.
Normal operation.
Adjust thermostat to
temp level.
1. Unstable pilot.
2. Pilot tube blocked or restricted.
3. Oxidation build up on pilot electrode.
4. Wire damage to pilot assembly or bad
connection at gas valve.
1-4. Page 19
1. Pressure switch tubing kinked or blocked.
2. Blocked pressure tap on switch or blower.
3. Faulty pressure switch.
Page 20
1. Vent blockage or improper vent configuration.
2. Pressure switch tubing kinked or blocked.
3. Faulty pressure switch.
4. Blower not spinning up to speed.
5. Blower temp or exhaust temp too high.
6. Faulty blower temperature switch.
1. Check vent or vent
tables
2 & 3. Page 20
4. Page 22
5 & 6 Page 23
1. Thermal well sensor out of calibration.
2. Faulty gas control.
3. Plumbing leak
1-2. Replace gas
control, page 26
1. Pilot valve stuck in open position.
Replace gas control,
page 26
None, control LED not on
or flashing No electrical
power Control power switch in “OFF” position.
Supply voltage interrupted.
Turn power on.
Page 12
Observe green LED indicator on Electronic gas
control. Error flash codes are displayed with a
three second pause before repeating. Check
and repair the system as noted in the
troubleshooting table below.
Green LED
Indicator
12