Sensors - Rheem 325 II Series Service Instructions Manual

Component Test 1

Sensors

The sensors are identified as follows:
Tank sensor
Evaporator sensor
Compressor sensor
Heat exchanger water outlet sensor
All four sensors are identical and each can be tested as per the following instructions.
Unplug the relevant sensor from the controller and remove the sensor from its
location so its temperature will be the same as the ambient air temperature. The
sensors all have different connectors to aid with correct reinstallation.
As the evaporator sensor is difficult to remove, it may be best left in place, as long as the
evaporator coil temperature can be confirmed.
Using a multimeter set on the resistance (kilo-ohms) scale, measure between the two pins
of the sensor plug*. As the resistance of each sensor will change according to its
temperature, the resistance measurements for each sensor will need to be checked
against the Sensor Temperature / Resistance Table below, and the value then compared
to the ambient air temperature.
* Note: The sensor plug sockets are quite small. Fine Probe Adapters (available from
Rheem Spare Parts, part number WH0020082) can be utilised as probe extensions.
Alternatively small pins may be used, however ensure good contact is made when testing.
Sensor Temperature / Resistance Table
The table below sets out the resistance of the sensors for a given water or air temperature.
TM077: 325 & 410 Series II Heat Pump Service Instructions
Rev 00: Issued April 2014
This document is stored and maintained electronically by
Temperature (°C)
0
10
20
30
40
50
60
70
80
Resistance (kΩ)
23.73
15.45
10.31
7.037
4.905
3.485
2.521
1.853
1.384
Service. All printed copies are deemed uncontrolled.
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