A.O. Smith 120 trough 500 - Manual (Page 30)

BTR TANK TYPE HEATERS
SERVICE HANDBOOK
A.O. Smith Water Products Service Handbook
Irving, Texas ©2000 Training Department
29
NORMAL OPERATION (continued)
Condition:
• Thermostat closed, damper in process of opening
STEP B TEST FOR 24VAC BETWEEN BLACK AND ORANGE
IF THEN
24VAC is present Continue to Step C.
24VAC is not present See Troubleshooting Step A2
Condition:
• Thermostat closed, damper fully open
STEP C TEST FOR 24VAC BETWEEN BLACK AND YELLOW
IF THEN
24VAC is present Continue to Step 11
24VAC is not present See Troubleshooting Step A3