How to fill your combi boiler

My combi boiler has stopped working, first check the water pressure on the boiler if the water pressure is low in your combi boiler, simply try and top it up using the filling loop.  

These are known as a “Pressurised Systems” and if the pressure drops below a certain pressure the boiler will switch off. 

The boiler will have a gauge and will normal be between 1 to 1.5 bar when cold, if you see the picture of the gauge it is marked green for the normal working range it will increase as heating temp increases and there is also red line for minimum and maximum pressures, note the pressure is to low in this system when in red.

Re-Pressuring the System

You will need to use a filling loop to re-pressurize the system (this will allow mains water pressure into the system), this may be part of the boiler or a flexible pipe (see picture) check with the boiler manufacturer if unsure.
After you have connected the filling loop just open the valve to let the mains water pressure top up the system, slowly open the valve on the filling loop, until the correct pressure is seen on the gauge (normally 1 bar).

Why Has It Lost Pressure?

Minor leaks can cause pressure drops over time, possibly several months or even a year, bleeding a radiator will cause the system to lose water pressure.
Larger leaks may be more visible. Hidden pipework in solid floors and walls my hard to find.

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

Emergency Plumber 24|7 Ltd
01225 247 247

Bristol, Bath, Weston Super Mare, Portishead

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