Bradford White M1TW40S Series Service Manual page 13

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.
LED Status
None, control LED not No electrical
on or flashing power
Stand-by mode,
Short flash, once every
Waiting for call for
four seconds
heat (no fault).
"Heartbeat", alternates Thermostat calling
bright/dim for heat (no fault).
Weak pilot signal
Short flash once per
on last call for
second
heat.
Pressure switch
Two flash, three
not working-
second pause
closed position.
Pressure switch
Three flash, three or blower temp.
second pause switch not working
-open position.
Excessive tank
Four flash, three temperature.
second pause System must be
reset. (See Pg. 24)
Undesired-false
Five flash, three
pilot flame
second pause
present.
Control
Status
Control power switch in "OFF" position.
Supply voltage interrupted.
Temperature demand is satisfied
Tank temperature below set point of thermostat.
1. Unstable pilot.
2. Pilot tube block or restricted.
3. Oxidation build up on pilot electrode.
4. Wire damage to pilot assembly or bad
connection at gas valve.
1. Pressure switch tubing kinked or blocked.
2. Blocked pressure tap on switch or blower.
3. Faulty pressure switch.
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. Thermal well sensor out of calibration.
2. Faulty gas control.
3. Pluming leak.
4. Tank not filled with water.
1. Pilot valve stuck in open position.
Probable Cause
Troubleshooting
Green LED
Indicator
Service
Procedure
Turn power on
Normal operation.
Adjust thermostat to
temp level
Normal operation.
Adjust thermostat to
temp level
1. Page 15
2-4. Page 17
Page 18
1. Check vent or vent tables.
2 & 3 Page 18
4. Page 20
5 & 6 Page 22
1. Page 24
2. Replace gas control,
page 24
Replace gas control,
page 24
Page 13
Page 13
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