SERVICE PROCEDURE MCE-V
High Limit (ECO) Testing
Page 19
1. This procedure assumes line voltage, tran sformer,
fuses, and thermostat are in working order.
2. Turn power “OFF” to water heater .
3. Remove lower control box cover and remove insulation
from insideof controlbox.
4. Check for continuity across terminals 1 & 2.
(see illustration 7)
A) Continuity IS present, ECO is okay.
B) Continuity NOT present, proceed to step 5.
5. Verify power to the water heater is “OFF”, firmly press the ECO
reset button. Recheck continuity across terminals 1 & 2
(see illustration 7).
A) Continuity IS present, the ECO has previously opened indicating the water i nt he tank, at
some point did overheat, Check the following:
1. Thermostat must be in full contact with tank.
2. Be sure heating element(s) is not shorted to ground (see page 15).
3. Proper thermostat operation (see page 22).
B) Continuity NOT present, water in tank may be over heated.
1. If water is overheated, verify that power to water heater is “OFF”. Flow water through the t ankt o cool
below set point of upper thermostat. Reset ECO and recheck continuity.
2. If water is cool, Replace ECO (High Limit).
High Limit Control (ECO) Testing for
600V Surface Thermostat Models
ECO reset
button
Illustration 7
DANGER
High voltage exposure. To avoid hazard to
life or property use extreme caution when
making voltage checks .
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