Thermistors Troubleshooting - EcoSmart ECO 8 Troubleshooting Manual

Activity A | Thermistors Troubleshooting
Each heater is equipped with two thermistors (see image above). One located on the inlet side (yellow wire)
and one located on the outlet side (red wire). The function of the thermistors is to measure the incoming
and outgoing water temperature and keep it within 1 to 2 degrees (+ or -) of the set temp shown on the LED
display. If the thermistors fail, the heater will still activate, however the control board will not send power to
the elements. Follow these steps to test the thermistors.
1. Turn OFF breaker
a. Once breaker is off, turn round knob to ensure no power is at the unit.
LED display will not light up if the correct breaker is off.
b. If LED display does illuminate, the correct breaker was not turned off.
2. Unscrew front cover of unit. You will notice a "Warranty Void if Seal Broken" sticker, disregard this.
a. Warranty will not be voided. This sticker is there for safety purposes to ensure customers
contact technical support before opening the unit.
3. Locate white plastic cover covering control board and remove.
a. Cover is secured with Philips head screws, one in each corner.
4. Locate thermistor on control board (see image above).
a. Disconnect inlet and outlet thermistors from control board.
i. Both wires are quick-connect style. To disconnect, gently pull on wires until unplugged.
ii. Inlet is yellow
iii. Outlet is red
5. Turn breaker ON
a. Leaving thermistors unplugged, turn breaker back to ON position.
6. Run water
a. Turn on the hot water tap for approximately 45/60 seconds. During this time, the unit should
begin to heat water.
b. Make sure LED display is illuminated on heater.
i. If it is not, check that the correct breaker was turned on.
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