Keeping your boiler at its preferred pressure level is vital. If it’s too high or too low, you risk shutting it down completely, leaving you without heating or hot water. In some extreme cases, it can lead to damage.
While the optimum pressure will vary between different models and manufacturers, the vast majority operate best between 1.0 and 2.0 bar if it’s on and 1.0 and 1.5 when it’s off. It’s important to remember that there is some leeway here and generally no cause for concern unless the pressure has strayed too far one way. Generally, this will be below 1.0 or above 2.5 bar.
Often, the boiler will highlight when this has happened. Analogue gauges should have red highlighted areas to illustrate when the pressure is too high or too low. If you have a digital monitor, then there should be an error message with the next steps.
How do I increase the pressure?
Turn off the boiler and find the external filling loop which should be under the boiler, you can recognise it as a braided tube linking two pipes, each one will have a lever at the end*
Turn both levers so they are facing the same way as the braided tube
You should hear the water filling and see the pressure rising
When it approaches 1.2 bar, turn the levers back
If the pressure stays stable, then you can turn the boiler back on
*While the external filling loop is a fairly standard mechanism, it is not uniform. If you cannot find it, then you will need to consult your boiler manual.
How do I relieve the pressure?
Turn off the boiler and ensure that the filling loop valves are firmly closed
Bleed each of the radiators, if you don’t know how you can search online or get a plumber to do it for you
Once you’ve bled the radiators, check the pressure, if it’s around 1.2 bar, then you can turn it back on, if it’s too low, you will need to bleed the radiators again
If the pressure has gone too low (below 1.0), then you will need to increase the pressure
Once you’ve got your boiler back to its optimal pressure level, you will want to keep an eye on it over the next couple of days.
How often should I need to change my boiler’s pressure?
While this will of course vary, it shouldn’t be more than a couple of times a year. If you find the pressure is requiring attention more than this, then you may have a leak, and will most likely need to speak to a professional to get the issue resolved.
