Boiler Pressure Guide

How to fill up the water in your boiler should the pressure drop

Checking the boiler water pressure 

A common occurrence that causes problems with central heating systems is a lack of water pressure in the system. Most Combi/System boilers require a pressure of at least   1bar, and the recommended pressure tends to be between 1 and 1.5 bars of atmospheric pressure. You should check the operating manual for the recommended pressure before topping it up. Most boilers will have a dial or gauge to show the current pressure with a working range indicator. Generally, the water pressure indicator is located on the front of the boiler. The pictures show an analogue gauge and a digital gauge (from the current Valliant range) for an example. Newer boilers might have a digital indicator. As above if it reads less than 1 bar, check the recommended level and the follow the steps below to refill your boiler water pressure.

Refilling Boiler Pressure 

1. Find the cold water input feed or filling loop to your boiler (usually a plastic tube or copper pipe underneath or beside the boiler with one or two taps or valves) see photos

2. Using the small tap or valve on the cold water feed/filling loop slowly turn until the boiler pressure indicator display reads between 1 - 1.5 bars.  This will only require 1-2 gentle turns, or a quarter turn depending of the tap/valve. Fill the system slowly and do not overfill.

3. When the gauge reads between 1 - 1.5 bars (or the recommended pressure on your system), Close the tap(s) 


Should the pressure in your boiler drop and you need to fill it more than twice in 24 hours please ring  Dave asap as there may be a fault with the boiler.