Combi boiler/heating

[DirtyHabit]

I have done a fair bit of plumbing but have not had much to do with combi boilers. I need to move a radiator. What is the procedure for refilling the system?

[pilotlight]

I assume that the system is a " pressurised sealed system " type, i.e. no header tank, and a pressure guage on the combi.

Some combis have heating system isolating valves underneath, which would mean that you could use these to carry out your alteration whilst leaving the combi to provide hot water if needed. Otherwise, switch off the power at the isolation switch and drain the system. Once you have completed your alteration, you should then re- introduce a system inhibitor.Then re-fill by using the " filling loop ", which will be adjacent to the boiler. ( this is usually a silver coloured flexible small pipe, that may, or may not have been left connected.) Open the small washing machine type valve and you will hear the water entering the system. The indicator on the pressure guage will start to rise -- allow the system to fill to 1 bar. Now you will need to check all the radiators, and release the air if required. This obviously will cause the pressure to drop again, so re-pressurise as required. When the system is air free, ensure that the pressure is set at 1 bar, switch power back on , and re-adjust the programmer if required.

A very few combis have their own inbuilt filling key. If there is no filling loop, check for this.

Hope this helps.

[DirtyHabit]

Thanks pilotlight,
Much as thought, just that I have only had experience of open,header tank system.