How to Repressurise a Boiler: Step by Step

how to repressurise a boiler
When the pressure is in the red, it is time to consider repressurising the boiler (Image credit: Future)

Repressurising a boiler is a relatively simple job and can be done on a DIY basis. However, there are two main ways to top up your boiler, either via an external filling loop or an internal filling loop (either keyed or keyless) – and both methods are demonstrated in the video and the step-by-step guide below.

Topping up a boiler with mains cold water is a routine aspect of maintaining a boiler’s life cycle. You may have noticed that your heating has become less efficient, or that the pressure gauge on your boiler turns to red. 

Sarah Handley

Sarah is a journalist, editor and the former Web Editor of She began her career more than a decade ago, working on the editorial team of Public Sector Building magazine, before joining the wider Homebuilding & Renovating team as Social Media Editor in 2012. Since purchasing her first house in 2015, Sarah has been adding to the ever-increasing list of home improvements she needs to make; including extending over the garage, resurfacing the driveway, replacing existing flooring and revamping the kitchen. Fortunately, her time with Homebuilding means she is not short on design inspiration or top tips to tackle or project manage these tasks herself.