A.O. Smith 120 trough 500 - Manual (Page 41)

BTR TANK TYPE HEATERS
SERVICE HANDBOOK
A.O. Smith Water Products Service Handbook
Irving, Texas ©2000 Training Department
40
STEP 18A MAIN GAS VALVE CHECK
BTR 120 – 400 GAS VALVE
STEP 18A. MAIN GAS VALVE CHECK. Disconnect wires from gas valve TH and TR
terminals. Using a multimeter, test for 68 ohms plus or minus 5 between TH and TR on
the main valve coil.
IF THEN
The meter reads ‘O’ or infinity • Replace the gas valve
The meter reads 68* ohms plus or minus 5 • The main burner will ignite
TH
TR