Thermostatic Cartridge

- Oct 26, 2018 -

Before talking about thermostatic valves, we talk about the phenomenon of hot expansion and cold contraction at first. Our most common thermometer captures this phenomenon well.


The thermostatic cartridge combines this hot expansion and cold contraction with the piston.

The piston lies between the cold water inlet and the hot water outlet.

After setting the temperature value, if the water outlet temperature is low, the temperature sensor moves the piston towards the cold water inlet, making the cold water inlet smaller and the hot water inlet larger. The temperature will go up. At the set temperature, the piston stops moving.

If the effluent temperature is higher than the set value, do the opposite action.


From electronics, this is a negative feedback phenomenon. If the temperature is high, I will pour out the hot water and add cold water, so that you can quickly reduce the temperature. If the temperature is low, I will get cold water and add hot water into it. This is a constant search for balance.


The sensitivity of the temperature sensor determines the sensitivity of the spool.

The piston determines stability.

Thermostatic cartridge structure

There are two main types of thermostatic cartridges on the shower faucet, one is high purity paraffin as heat-sensitive material, the other is memory spring as heat-sensitive material.

The following is a thermos-sensitive head.

The use of wax type constant temperature spool will have to say the French "VERNET" (Wan Nai) company. A constant temperature spool of RMB close to two hundred yuan, really not cheap! If the production of thermostatic faucet manufacturers do not know (Wan Nai) this brand can not be passed.



The picture below is a combination of piston core and thermos-sensitive temperature sensor.

There is also a constant temperature spool, which is represented by the Japanese TOTO company, using the memory spring as the thermal element.


Several more constant temperature spool dismantling plans.

  • Bidet Toilet Faucet
  • Hand Held Shower Heads
  • Bathroom Basin Faucets
  • Wall Mount Sink Faucet
  • No Return Check Valve
  • Three Way Angle Valve

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