Service Procedure V: Thermostat Testing - Bradford White ElectriFLEX HD CEHD 50 Service Manual

Immersion Thermostat Operation Testing
Providing the water temperature in tank is within the operating
range of the thermostat, checking thermostat operation can be
as simple as rotating the thermostat dial and listening to the
contactor(s) to see if they respond to a call for heat.
Use caution and turn Power "ON" and rotate the thermostat dial to call for heat. With
water temperature below the thermostat setting, the contactor(s) close. With the contacts
closed, use caution and check for rated voltage across lower terminals of contactor(s)
(see illustration 7), If rated voltage is present, the thermostat is calling for heat.
Rotate thermostat dial to the minimum setting. With water temperature above the
thermostat setting the contactor(s) will open. With the contacts open, voltage should not
be present at lower terminals of contactor(s).
Follow the procedure below If preliminary testing above does not verify thermostat
operation.
Thermostat Control Continuity Testing
1. This procedure assumes line voltage, Hi Limit Switch, and contactors are in working order.
2. STOP, DANGER! Turn power "off" to water heater.
3. Open door or remove lower control panel cover and insulation.
4. Locate thermostat control (see general control layouts on page 5) and remove wire leads to control screw terminals.
5. Water temperature in tank must be within operating range of thermostat for this test. If above or below, it will be
necessary to drain tank and remove thermostat bulb from tank to warm or cool the bulb to be within operating range of
thermostat.
6. Set multi-meter to the "Ohms" setting.
7. Rotate thermostat dial to highest setting.
8. Check across screw terminals of control
(see illustration 8)
A) Continuity IS present, okay, go to step 9.
B) Continuity NOT present, replace thermostat.
9. Rotate thermostat dial to lowest setting.
10. Check across screw terminals of control.
(see illustration 8)
A) Continuity NOT present, thermostat is okay.
B) Continuity IS present, replace thermostat.
16
Service Procedure V:
Thermostat Testing
16
WARNING
High voltage exposure. Use caution when making
voltage checks to avoid hazard to life or property.