A.O. Smith 120 trough 500 - Manual (Page 23)

BTR TANK TYPE HEATERS
SERVICE HANDBOOK
A.O. Smith Water Products Service Handbook
Irving, Texas ©2000 Training Department
22
STEP 4 INSPECT THE DAMPER
STEP 4. INSPECT THE DAMPER. Lower the thermostat setting so the unit will not be
calling for heat, then inspect the damper.
IF THEN
If the damper is open: • Go to step 5.
If the damper is closed: • Go to step 7.
Note: If the water temperature in the tank is below 120 degrees F, temporarily disconnect the
jumper wire between the high limit and thermostat to simulate a satisfied thermostat.
STEP 5 CHECK THE PC BOARD
STEP 5. CHECK THE PC BOARD. Test for 24 VAC between the black PC board wire
connection and ground.
IF THEN
24 VAC is not present: • Check the black wire connections
between PC Board and high limit.
24 VAC is present: • Go to step 6.
E E f f f f i i k k a a l l D D a a m m p p e e r r O O p p e e n n