Service Manual

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Immersion Thermostat Operation Testing
Thermostat Specification:
 Calibration: 184°F/176°F
 Max Differential: 6°F
 Operating Range 80 to 180°F
Provided that the water temperature in the 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.
Using caution, 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 Figure 6), 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, ECO and
contactor(s) are in working order.
2. STOP, DANGER! Turn power “OFF” to water
heater.
3. Open control panel door.
4. Locate thermostat control (see general controls layout
on page 4) 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
immersion 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 Figure 7).
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 Figure 7).
A) Continuity NOT present, thermostat is okay.
B) Continuity IS present, replace thermostat.
Figure 6
Figure 7
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