Do you have a leaking pressure relief valve?

It’s easy to drop into ‘tech’ speak when talking about the intricacies of a boiler.

At UK Leak Detection, we believe in explaining how our process works and how parts that can cause leaks function, often we identify this common part as being faulty and this can be identified in most instances before we attend, possibly saving you the cost of leak detection. Failed PRV’s are a quick leak detection for us, but not the most cost effective for our customers, it’s not common but each engineers sees a failed PRV about once a month.

One of the common things talked about is the Pressure Relief Valve or ‘PRV’, a small device that stops the water pressure from building up beyond the point that is considered safe. This is normally 3-bar on most heating systems, on old money that is about 44-psi, more than you put in the average car tyre!

This a small spring operated valve, that fails at 3-bar and drops the pressure back to safe levels.

The usual reason for these operating is either the system is filled to a high pressure by mistake and exceeds the 3-bar from incoming water pressure (if you have better than 3-bar) or filled to a high pressure when cold and then being triggered as the water heats and pressure builds to over 3-bar.

Like all components, they can just fail or once triggered often then never quite seal back up, this results in the pressure dropping and an incorrect diagnosis that there is a leak on the heating pipework.

In reality, the water is being slowly discharged out from the relief pipe, normally located outside. The water will often evaporate before it can be noticed on the ground, but brown rust or lime-scale stains are a good indication it has been leaking.

It is quite simple to test is the PRV is leaking, however if you have any doubts you should consult an engineer.

The PRV and discharge pipework should NEVER be blocked, however slipping a small balloon over the pipe will allow you to trap and water before it can evaporate, whilst allowing any excessive pressure to blow the balloon off the pipe before it could build to any level.

If you have any questions, please call us on 0800 228 9000 to discuss your leak detection.

Next we will talk about the other ‘PRV’ the pressure reduction valve…