Lochinvar 000 - 500 Installation And Service Manual page 45

STEP 1:
Is the pilot lit?
YES
Is the gas valve
STEP 2:
getting 24VAC?
YES
STEP 3:
Unit is running.
TROUBLESHOOTING GUIDE
90,000 - 270,000 Btu/hr Models - Water Heaters F1
NO
NO
Check 24VAC at R and W on
the (EMS) terminal strip.
Check all safety limit devices.
Check 4-pin low water cutoff
connector.
Check for gas. Check the pilot
assembly and thermocouple.
Check the gas valve for proper
operation. Clean and replace.
Is there 24 VAC
(purple wire) on the 4-
pin connector plug on
the temperature
controller?
NO
NO
YES
45
Check for an open
sensor. If not open,
replace temperature
controller.
NO
Is there 24VAC
(tan wire) on the
4-pin connector
YES
plug on the
temperature
controller?
YES
Check X and B on the
terminal strip if the flow
switch is installed. Check for
an open auto reset high limit.
Check vent damper 3-pin,
louver relay connectors, and
venter proving.
Check the vent damper or
the vent damper plug and
the voltage to and from the
transformer.