Temperature Sensor Therm 895-1

Sensor measuring the water temperature at the outlet of the heating coil. Sends a signal to the thermostat that regulates the burner's operation.

Application

The sensor is fitted in the water line in the combustion chamber, right next to the temperature sensor tee (T-Einschraub-Verschraubung, 44.173) and the measuring cable clamp (Klemmring für Messleitung Thermostat, 44.087 1). It measures the current water temperature, on the basis of which the thermostat switches the burner on and off.

Symptoms – when to replace

• Water temperature doesn't match the thermostat setting, despite a sound burner and sound regulating knob.
• The burner doesn't respond to changes in water temperature – it runs continuously or doesn't switch on at all.
• Unstable, fluctuating water temperature during operation, despite a constant thermostat setting.
• Visible physical damage to the sensor or its measuring cable when disassembled.

How to choose the right part

Selection is based on reference number 449541 – it applies to the therm 895-1, 1165-1, 715, 1017 and therm-RP. The therm C and therm CA models require a different sensor (44954, without the suffix), despite an identical function.

When replacing the sensor, check the condition of the measuring cable (Messleitung Thermostat, 44.101 2) and its mounting clamp – an incorrect temperature reading may result from a damaged cable, not only from the sensor itself.

[faq]

Does the same sensor fit the therm C or therm CA?|No – these models require a different sensor (44954, without the "1" suffix), despite having the same water temperature measuring function. The numbers are not interchangeable between series.

The burner runs continuously despite reaching the set temperature – is that the sensor's fault?|That's possible – a damaged sensor can send an incorrect (too low) temperature reading to the thermostat, so the burner never receives the signal to switch off. It's worth comparing the actual water temperature with the thermostat's reading.

Does removing the sensor require draining water from the system?|Yes, replacement requires depressurizing the high-pressure system – it's best to shut off the water supply and release pressure by opening the gun before starting disassembly.

Does the measuring cable (Messleitung) also need to be replaced when replacing just the sensor?|If the cable is in good condition, it can be reused. It's worth replacing if it turns out to be damaged during disassembly or its insulation is cracked.

I replaced the sensor but the temperature problem persists – what else should I check?|Check the thermostat itself and its knob (44.153) – if the signal from the sensor arrives correctly but the burner still doesn't respond, the cause may lie in the thermostat rather than the sensor.

[/faq]