Understand correct boiler pressure and how to fix it if it is too low.

Understand correct boiler pressure and how to fix it if it is too low.

Checking your boiler’s pressure and re-pressurising it is something that you can do for yourself.

We always advise that you turn on your heating before the autumn to check that it is working properly.

This will save you from the problems that often arise in the winter, when the boiler breaks down and Gas Safe engineers become overburdened with work and unable to come out as quickly as you might need.

Often, when they do come out, they find that the cause is a frozen outlet pipe and we have explained in a previous blog how you can deal with that yourself.

Another common problem engineers come across is when the boiler pressure is too low.  This can mean that your heating is not as efficient or as warm as you expect.

Again, checking the boiler pressure and re-pressurising it is something that you can do for yourself.

Boilers need constant water pressure to function properly; water flows into the boiler from the mains water supply and keeps the boiler pressure at a relatively constant level. Most boilers should be at one bar of pressure.

In general boilers come with a dial on the fascia, showing the pressure level, with green showing the optimum level, which is where the needle on the dial should be, and red showing when it is too high.

Common causes of low pressure are if you have recently bled radiators to remove air bubbles, or if there is a leak in the pipework somewhere. So, if the pressure is low it is worth checking around your property for any tell-tale damp patches visible.

Most of the most popular makes of boiler come with information about how to check the pressure and boost it if it is below the optimum level.

There may be a tap you can use to refill the water in the boiler, or a screw you need to twist to recalibrate the system.

Both Viessman and Worcester-Bosch include guidance on their websites to help you to understand and deal with boiler pressure problems.

If you are having to boost the pressure too frequently, however, you may need to call in an engineer.

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