Service Manual

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 mustbe
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
desired temp. level.
Tank temperature below setpoint of thermostat.
Normal operation.
Adjustthermostat to
desired temp.level.
1. Unstablepilot.
2. Pilot tube blocked or restricted.
3. Oxidation builduponpilot electrode.
4. Wire damagetopilot assembly or bad
connection at gasvalve.
1-4. Page 18
1. Pressure switch tubing kinked or blocked.
2. Blocked pressure tap on switch or blower.
3. Faulty pressure switch.
1-3. Page 19
1.Vent blockageorimproper vent configuration.
2. Pressure switch tubing kinked or blocked.
3. Faulty pressure switch.
4. Blower not spinninguptospeed.
5. Blower temp or exhaust temp too high
6. Faulty blower temperatu
re switch.
7. Intake vent length exceeds exhaust vent length.
8. Frozen intakeorexhaust vent terminal.
1. Check vent or vent tables
2 & 3. Page 19
4. Page 21
5 & 6. Page 23
8. Page 41
1. Thermal well sensor outof calibration.
2.Faultygas control.
3. Plumbing leak
1. Page 25
2. Replace gas control,
page 27 &29
1. Pilot valve stuck in open position.
1. Replace gas control,
page 27 &29
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 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
UPDX Series
(For models with serial numbers starting with K or later see chart on page 15.)
12