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If you have a combination boiler there may come a time when you have to drain the system and then refill it. This might be the case if you want to change one of the radiators in your home for a new designer radiator or perhaps fit a towel rail in your bathroom.
If you have a combination boiler you will need to re-pressurise the system after the new radiator has been fitted. The pressure in these systems usually sits between the 1 bar and 1.5 bar mark and you can usually find the pressure gauge fitted to the boiler. If the pressure drops below the 1 bar mark for any reason you may experience problems with the system and you might not have any hot water.
To top up the system to attain 1.5 bar you need to attach the filling loop hose that sits under your boiler. This connects your system to the mains water supply. Tighten the hose onto the filler connector and then slowly open the tap to let mains water into your system. You should see the pressure gauge rising. If the system becomes over pressurised your boiler will release some water using its safety valve. Remove the loop after filling.
If the pressure in your central heating system keeps falling and you have to keep topping it up, you may have a water leak on the newly fitted radiator so it needs to be investigated further.