IMPORTANT

If you have not done this sort of thing before or are not totally confident in your technical abilities, you should not attempt to repressurise a boiler. There are many different kinds of combi boiler and repressurising systems vary greatly.

For this reason it is not possible here to instruct you on what to do or how to do it. The information below is for informative purposes only - not instructions for you follow.

You must refer to the manufacturers handbook for detailed information about repressurising. Also, there are some very good videos on the web/youtube that might help you. Here's a useful link: http://www.glowzone.co.uk/how_to_video.html

Similar to bleeding radiators from time to time, this is one of those maintenance tasks that, as a tenant, you are responsible for. However, if repressurising becomes necessary too often, say at least every month or two, then report this anyway as there may be a leak that needs fixing. Don't worry, this would be a repair that the landlord would pay for.

Remember, if you are not confident that you can do this properly or safely and do not know anyone who can do this for you, call us to report the problem.

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Repressurising a combination boiler

When a combination boiler ("combi" boiler) stops working, it could be because the water pressure is low inside the boiler. A "combi" a pressurised system and if the pressure drops below a certain level the boiler will switch off.

Most boilers will have a gauge and should normally be around 1 bar when cold (this will increase slightly as the heating temperature increases). If more than 2.5 bar, an engineer will need to reduce the pressure.

A flexible filling loop (shown below) is usually used to repressurise the system by allowing mains water into the radiator system. Although filling loops should be disconnected and removed when not being used, often they are left connected with the valves turned off.

When the filling loop is connected the valves should be slowly opened to let the mains water (which should be at a much higher pressure) top up the system until the correct pressure is seen on the gauge (normally 1 bar).

Some boilers may have a filling key that would have been supplied with boiler.

READ the manufacturer's handbook/manual.

Why has the system lost pressure?

Very minor leaks can cause pressure drops over a long time, possibly several months or even a year. Also, bleeding a radiator will cause the system to lose pressure.

Larger leaks may be more visible and leave a stain. Hidden pipework in floors and walls make leaks harder to find.

Tip! Check for minor leaks when cold, as expansion can cause minor leaks to seal and the leak also evaporates away.

Remember, if you're ever in doubt of your DIY abilities it's best to call in an engineer to do the job for you.