Pressure Relief Valve 15mm 3 bar

Every sealed heating system needs a safety valve, and a pressure relief valve 15mm 3 bar is the standard choice. It opens if the pressure in the system goes over 3 bar and lets water out to the discharge pipe.

When to use a pressure relief valve 15mm 3 bar

You will find one on combi and system boilers, and on sealed system kits with an expansion vessel. If the vessel loses its charge, or the filling loop is left open, the pressure rises as the water heats. This valve stops it going over the limit. So if you see it dripping, check the vessel and the filling loop first.

• Size: 15mm
• Opens at 3 bar
• For sealed heating systems
• Used on boilers and sealed system kits

Fit it with nothing between the valve and the system that could isolate it. Run the discharge pipe to the outside, where it can be seen and will not hurt anyone. Once a relief valve has passed dirty water, it often keeps weeping, so a new one is cheap insurance.

Sealed system parts in Glasgow

Unvented cylinder valves sit in the same pressure relief valves section.

Drop into Plumb Parts at 555 South Street, Glasgow G14 0QX. Times: Mon-Fri 8am-5pm, Sat-Sun 8am-1pm. Online orders are open as well.

Specification

• Sizes: 15mm, 3 bar
• Suitable for: Sealed heating systems, boilers and sealed system kits

Common Questions

Why does my 3 bar relief valve keep dripping?

The pressure is reaching 3 bar, so check the expansion vessel charge and make sure the filling loop is fully shut. Once a valve has passed dirty water, it may keep weeping and need changing.

Can I adjust a 3 bar pressure relief valve?

No, the opening pressure is fixed. If your boiler or system calls for a different figure, fit a valve with that rating instead.

Where should the 15mm discharge pipe run?

Take it outside to a point where any discharge can be seen and will not splash anyone. Never put a valve or cap between the relief valve and the boiler.