Safety valve 8115 6 bar 1/2 inch, solar 8115.15.153

Solar system overpressure protection

Membrane safety valve 8115.15.153 is used to protect installations with solar collectors from exceeding the allowable pressure – in this case 6 bar. It is designed for operation with liquids, including water‑glycol mixtures, at a maximum temperature 160 °C. Glycol may constitute up to 50 % of the medium volume – making it suitable for freeze‑protected systems.

The valve with a 1/2" (DN15) diameter is a typical choice for installations with collector area up to about 50 m². In practice this means it can effectively protect systems with a thermal power up to 171 kW – corresponding to typical residential or small commercial solar installations.

Why this setting and size?

A 6 bar setting is not accidental – it allows safe operation of the system at high temperatures, when the fluid expands under solar heating. Compared with lower settings (2.5–4 bar), this value handles cyclic pressure rises better in fully insulated circuits where temperature can exceed 90 °C. Therefore you do not have to worry about frequent valve opening during normal operation – it opens only in emergency situations.

Installation is simple: the G 1/2" thread enables direct connection to the pipe or a collector elbow, without the need for additional fittings. The membrane construction provides precise opening and tight closing after pressure drops – there is no “leaking” or “choking” as in piston valves.

Application and limitations

It is not suitable for flammable gases or aggressive media. It works exclusively with neutral liquids – water, glycol, unsaturated water vapour. In installations with flat‑plate or tubular collectors it is a standard protection element – both for manufacturers and installers who want to avoid damage to pipelines or storage tanks.

It is worth remembering: if the installation exceeds 50 m² collector area, a DN20 (3/4") valve should be considered. This model is not an “additional protection”, but a necessity – because with a larger fluid volume and greater volumetric expansion, a 1/2" valve may not be able to discharge enough medium during a failure.