Low temperature switch is developed for low temp. monitoring and frost damage prevention.As frost protection switch, it has been widely used in water treatment,water supply,and HVAC air conditioning,especially in cold area. The switch has a long copper capillary tube as sensing parts which is full of vapor. When temperature of the part is below setup point, the inner contact point won't disconnect.

The low temperature limit controller works on the mode of single-pole double-throw. It is suitable for hot water coil pipe unit,cold water pipe unit,liquid working pipeline,heat exchanger and surface air cooler. The low temperature limit switch features compact size, high reliability,quick response action,direct reading dials to indicate setup value and convenient to set temperature controlling point.

Working Mode

Wrap the long sensing capillary tube onto pipeline to detect low temperature and do related protection action. When any 200m length part of sensing capillary has its temperature below setup point, inner switch will be off until temperature are rising up, and over 2℃ or 2.5℃ than set temperature,then switch will re-connect.
The sensing part of capillary tube has vapor,and main body has adjustable enclosure.If capillary tube is cut, the whole temperature switch controller won’t be repaired and completely bad.

Installing Notes:

  • While installed on the wall, please drill installing hole as instruction and then use self-tapping screw to lock.
  • Environmental temperature shouldn’t be lower than setting temperature. Avoid installing in the near accidental cold,hot source and outdoor or environment that will make sensing capillary over 80℃
  • Don’t heavily press sensing capillary,otherwise it will change the calibration result to damage accuracy class.
  • In order to ensure right and reliable action, should at least wrap over 200mm length sensing capillary onto pipeline of related protection devices.
  • Sensing capillary tube of low temperature controller should be installed at leeward side of surface air cooler and heat exchanger.
  • In order to avoid electric shock or damaging, please make power OFF before wiring.

  • Working Mode: Single-pole,double throw(Low temp.open)
  • Controlling Temp.range:1.0-7.5℃
  • Return Temp.difference:2.0-4.0℃
  • Capillary tube length: 3m or 6m optional
  • Rated power:250VAC, no inductive current:5A, inductive current:4A

  • Working Mode: Single-pole,double throw(Low temp.open)
  • Controlling Temp.range:1.0-7.5℃
  • Return Temp.difference:4.5-5.5℃
  • Capillary tube length: 3m or 6m optional
  • Rated power:125VAC, no inductive current:8A, inductive current:6A250VAC, no inductive current:5A, inductive current:4A

This low temperature limit switch is different from two items above. Its sensing part is not capillary tube,but it is temperature bulb with air inside. The switch is equipped with two functions together: setting temp. function and adjustable of return temp.difference. Of course, if need capillary tube as sensing temp.part,we can prove special manufacturing.

Technical Specification:

  • Working Mode: Single-pole,double throw(Low temp.open)
  • Controlling Temp.range:-30-15℃
  • Max temp.of sensing bulb:45℃
  • Return Temp.difference:3-15℃
  • Protection class:IP54 
  • Rated power:110Vac or 220Vac. Can directly control equipment with power below 1KW. 

Note: Regular supply of this model is 1m capillary tube with temp.sensing bulb,and capillary doesn't sense temperature. 2m-6m capillary tube can be made as requirement.