Combination Boilers and Pressure Relief Valves

The Pressure Relief Valve is meant to act as a safety in case the boiler builds up too much pressure and needs to vent. You’ll find this type of system in Combination Boilers. As your boiler heats hot water in the Central Heating Loop the water expands. As it expands the pressure increases. That extra volume of water has to go somewhere or it will try to escape at the weakest point in the heating systems which could be a radiator valve, solder joint or the Pressure Relief Valve.

As the water expands the extra volume is taken up in the expansion vessel which contains a rubber bladder and as the water pressure increases the rubber bladder fills with the extra water. Recently our plumbers managed to get to a boiler just in time; we spotted the problem whilst completing a routine boiler check up in Wembley.

However, if for example the pressure vessel fails and the pressure cannot escape as I mentioned earlier it will force its way out in the form of a leak. You’ll also notice that the pressure gauge will start displaying a lower and lower pressure when the heating is turned off. Over a period of time you will have to keep filling the system by way of the filling loop.

We see this type of issue all the time and recently did repairs and maintenance checkups on different combi-boilers in Surbiton. If you have noticed anything different about your boilers performance, contact us today! We have heating and boiler engineers based all over London including in areas such as Uxbridge and Brixton.

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