If a small heater element is placed at the required liquid level of a flooded evap­orator, together with a heat-sensing element, then the latter will detect a greater temperature if liquid refrigerant is not present. This signal can be used to oper­ate a solenoid valve.

The thermostatic or electronic expansion valve can also be used to maintain a liquid level. The phial and a heater element are both clamped to a bulb at the required liquid level. If liquid is not present, the heater warms the phial to a superheat condition and the valve opens to admit more liquid.

Posted in Refrigeration and Air Conditioning