Maintenance and repair of direct-acting temperature regulators

Maintenance of direct-acting temperature controllers should be performed in accordance with the operating instructions and the recommendations below should be taken into account.

• Once a month, it is recommended to check the setting temperature using a control thermometer.
• Every six months, it is recommended to measure the hysteresis, time constant, and proportionality zone, comparing them with the values obtained during commissioning.
• If there are metering devices, it is recommended to measure the pressure drop in the fully open and leakage in the fully closed valve every six months, comparing them with the values obtained during commissioning.
• The mesh filter installed before the temperature controller should be cleaned as it becomes clogged. The clogging of the filter is determined by the readings of the gauges installed before and after it.

Repair of the temperature controller may be required if it fails to maintain the temperature. Reasons for the temperature controller failure are:

• Thermal element failure due to mechanical damage to the impulse line or temperature sensor. Most thermostatic drives cannot be repaired and require replacement.
• Valve boiling. It can be eliminated by cleaning the disc and seat after dismantling the temperature controller.

Direct-acting temperature controllers are reliable devices and rarely fail. Therefore, if you notice a deviation in temperature from the set value, before looking for the cause in the controller, check if the operating mode matches the calculated one.

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