Art. 791

Application
Anti-freeze valve for heating/cooling systems with heat pump. The anti-freeze valve allows to protect the pipes and the heat pump from failures caused by freezing of the water inside them.
In case of shutdown of the system during the winter season, if the water temperature drops and reaches +3°C, the valve starts to open allowing a discharge, initially modest: the outflow draws the water from the side of the circuit inside the building, having a higher temperature, thus preventing the formation of ice.
If the discharge continues due to cold temperatures, in the absence of a filling group, the internal pressure of the circuit runs out and tends to reach atmospheric pressure, thus making the outflow impossible: a vacuum breaker valve present in the upper part of the valve body intervenes to allow the intake of air, allowing water drainage to continue. 
The presence of an automatic circuit filling unit is recommended which, by restoring the pressure in the circuit, will bring the anti-freeze valve back to normal working conditions and the system will be able to restart autonomously.

Installation
The installation of two anti-freeze valves, one on the flow, the other on the return, is recommended. Otherwise the pipe that does not have it may not be emptied and may be damaged by any freezing.
The installation position is outside the building, at the lowest point of the system, in a position close to the heat pump.

Technical specifications
- Forged body in brass alloy. Yellow brass finish;
- Maximun static pressure 10 bar (PN 10);
- Maximun medium temperature: 90 °C
- Ambient temperature range:  -30°C to +50 °C
- Opening start medium temperature: +3°C
- Closing start medium temperature: +4°C
- Accuracy: ±1°C
- Inspectable vacuum breaker valve;
- Inspectable cartridge for cleaning and replacing the sensor

Code 1” Male: 04791
Code 1”1/4 Male: 05791
Code 1”1/2 Male: 06791
Code 28 mm: 28791
Code 1” Male x swivel nut: 04791C
Code 1”1/4 Male x swivel nut: 05791C