RESISTANCE CONTROL THERMISTORS AND HARNESS

Set Appliance State:

Isolate Mains Power to appliance as per TOPs P4

Set Multimeter to Resistance

Remove thermistor connector from PCB

Measurement:

Measure resistance across each pair of
wires on the thermistor PCB connector.
Yellow wires - Dry fire thermistor.
Blue wires - DHW thermistor.
Pink wires - Return thermistor.
Red wires - Flow thermistor.

id isar he24 h49852 pcb thr dry fire connector dc.gif

id isar he24 h49852 pcb bottom connections.gif

Temperature Range (°C)	Resistance Range
0°C to 10°C	20.0kΩ - 34.0kΩ
10°C to 20°C	13.0kΩ - 20.0kΩ
20°C to 30°C	8.0kΩ - 13.0kΩ
30°C to 40°C	5.3kΩ - 8.0kΩ
40°C to 50°C	3.5kΩ - 5.3kΩ
50°C to 60°C	2.4kΩ - 3.5kΩ
60°C to 70°C	1.7kΩ - 2.4kΩ
70°C to 80°C	1.2kΩ - 1.7kΩ
80°C to 90°C	900Ω - 1.2kΩ
90°C to 100°C	700Ω - 900Ω

Resistances vary with temperature and should conform approximately to the table below:

Note: Clicking on the resistance table will switch between table and graph view.