CALEFFI is a European leader in the production of top-quality control and measurement fittings used for domestic and industrial applications in the heating, air-conditioning, sanitary installation and renewable energy sectors

Heat pump protection

The increase in popularity of heat pumps, including monobloc heat pumps, has contributed to the growing popularity of the Caleffi 108 series anti-freeze valve. Its main purpose is to protect the monobloc heat pump from freezing in the event of an electrical power failure.

How does the anti-freeze valve work?

The anti-freeze valve, installed in a heat pump system, allows a slow bleed when the medium temperature drops below 3°C. The valve is fitted with a specially calibrated thermostatic insert which opens the water bleed when the medium temperature in the valve drops below 3°C. The water bleeds off at the bottom, forcing its movement in the outer section of the system. The thermostatic insert closes the bleed at 4°C.

The amount of water that comes out of the system depends on many variables such as:

  • outside temperature
  • length of external sections
  • quality of insulation
  • installation water temperature

Figure 1 Installation diagram with automatic filling valve

Figure 2 Valve operating diagram

In the picture shown, the upper element is open because the outside air temperature has dropped below 5 oC. In addition, the system was deprived of electrical power and, for this reason, the medium in the system cooled down. The thermostatic element located at the bottom opened because the temperature of the medium dropped below 3 oC. At the same time, the vacuum breaker opens allowing the refrigerant to flow out of the valve. When the medium reaches the valve at a temperature of 4 oC the thermostatic element will close the outlet.

108 iStop wersja podstawowa

Figure 3 108 iStop basic version

Figure 4 108 iStop extended version

Which version to choose?

  • basic if the heat pump will be used as a source for heating
  • extended if the pump will prepare low-pressure heating and cooling medium.

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