How To Repressurise Your Boiler

Your hot water system requires a constant pressure level to ensure it works correctly. Generally it works by the cold water feed flowing through the system from the mains, however if there is a leak of some type or your radiators have recently been bled, you may experience a loss or increase of pressure that can mean no heating or hot water right when you need it.

You will be able to see if the problem is caused by a drop in pressure by taking a look at the gauges on your boiler. They are usually set at 1-bar and you will be able to see that it has dropped or increased, indicating there is an issue with your boiler or the heating system.

Your first port of call will be to try and reset the pressure and that may fix the problem completely. However if after you reset it, the pressure falls or rises again, you know you have a problem that needs the help of an expert.

The re-pressurising process

If you look in your handbook for your boiler there will be clear instructions for your particular boiler, however the following gives you the standard procedure that works for most combi-boilers.

Low pressure:

  1. Switch off your boiler and allow the whole system to cool down
  2. Locate the filling loop hose and ensure both ends are attached with valves
  3. Open both valves with a screwdriver (some have handles) to allow the cold mains water to enter the system. You will hear this flowing
  4. When the pressure gauge hits 1- bar you should turn off each valve in turn. It should then settle at this level. If not, it means the integral issue has not been solved

High pressure:

The pressure relief valve will usually ensure that any buildup of pressure is released ensuring your boiler is safe at all times. However if the gauge continues to show high readings there are steps you can follow.

  1. Check the valves on the filling loop to ensure they are closed and not loose
  2. Bleed your radiators and this should immediately reduce the pressure in your system

If these don’t work it might be a problem with the valves and they may need replacing by a qualified engineer.

Most of us will want to avoid the call out fees from a qualified gas heating engineer – so don’t be afraid to take the relevant steps for you boiler before you decide that expert help is needed. You might just solve the problem yourself.