Skip to main content

Ready to hire?

Post your job in minutes, browse real reviews and choose who to speak to.Post a job

Need some tips or advice?

Ask a question
Plumbing

Combi Gas Boiler Losing Pressure after British Gas Service

Anonymous user 11/11/2025 - 9.31 AM

The next day following a service I noticed that the pressure had dropped to 0.5, so I re=pressurised. I have had to do this on a daily basis since the service so have booked an engineer to visit on Weds - thinking it may be an expansion vessel or Relief valve issue? Yesterday the pressure rose to 3.5 when the heating was on so I turned the heating off. However ever since the pressure has remained at 1.5 and not dropped at all. I will still see what the engineer says but could the losing of pressure issue been a temporary issue, maybe trapped air?

Are you a tradesperson and able to answer this question?

Log in

4 Answers

Porter Builders

No reviews yet

Croydon
sounds like pressure gauge not working right, you been re pressureized and it goes over 3 bar, releases water and goes back down To me a dirty system causing the pressure gauge to give faulse reading. Fit external gauge to make sure
Answered16 November 2025
1

Michael soggee

Rating: 5 out of 5
Coulsdon
Sounds like the exspaion vessel needs topping up with air. I would also check the pressure relief valve and make sure its not constantly dripping if so that will need replacing
Answered16 November 2025
1

Joule Heating Ltd

No reviews yet

Bournemouth
Sounds like the expansion vessel has lost its air pressure, could be an air leak from when the engineer checked it during the service.
Answered3 November 2025
0

Anonymous user

It sounds like the expansion vessel but it is good to eliminate the possibility of air in the system. Go around each radiator and bleed them individually (start from the top)
Answered6 November 2025
0