Safety valve 8115 4 bar 3/4 inch, solar 8115.20.152

Solar system over‑pressure protection

The membrane safety valve 8115.20.152 protects installations with solar collectors from exceeding the allowable pressure – especially when the fluid in the circuit heats up and expands, and there is no way to discharge the excess energy. The 4 bar setpoint is selected for typical operating conditions of solar systems, where pressure can rise due to prolonged sunshine.

The valve is intended for the following media: steam, gases and liquids, including water‑glycol mixtures up to a maximum of 50 % concentration. It can operate at temperatures up to 160 °C, which corresponds to conditions in solar circuits during pump shutdowns or regulator failures.

For the installer – clear practical compliance

In practice, the DN20 (3/4 in) valve is the standard choice for systems with collector areas up to 100 m². This value is not an approximation – it results from flow and fluid‑volume analysis that the valve can safely discharge when opened. For example, if the installation has 85 m² of collectors, this valve provides an adequate safety margin without the need for a larger diameter. The 4 bar setpoint and G 3/4" thread are a standard combination for systems up to 140 kW – these parameters are consistent and verified by the manufacturer for specific applications. Installation is simple: the G 3/4" thread allows direct connection to standard piping in solar systems.

For the end‑user – what does it mean in practice?

When the solar system overheats – e.g., after a long hour with no heat demand – the pressure rises. The valve opens automatically, discharging the excess fluid and preventing damage to pipes, collectors, or the storage tank. No manual intervention is required – it works like a “pressure fuse.”

It requires no maintenance or adjustments. It is designed as a single‑use element – after opening and releasing the excess fluid, it returns to the closed position once the pressure falls below the setpoint.