I have closed off the valves on my radiator and removed it, I would like to change the pipes in order to fit a towel warmer radiator.I know there are a series of valve at the boiler to isolate pipes but I guess its impossible to remove those radiator cut off valves without introducing air into the system.So what is the procedure for bleeding a combi boiler and ensuring 1 bar pressure is reached?
Assuming you isolated the boiler before commencing work, reopen flow/return valves beneath charge the system up to 2 bar via filling loop. Bleed the towel rail and any rads. Ensure system has 1-1.5 bar in when this is done. The auto air vent on the boiler will bleed any air. Run the boiler without heat (no gas) to prevent any possible damage to heat exchanger (incase air in there). You will have to reset the boiler 3 or 4 times after the flame failure kicks in. All we want is the pump to run for a minute or so. When this is done check gauge/top up turn the gas back on underneath and you should be ok.
Once rads are reffitted re pressure the combi with the filler tap (normall found under boiler on cold supply) and bleed the radiater's starting with the nearest to the boiler, letting the air out of the bleed nipple found on the top left or right of the rad, do this on all rads even if they never lost water. Tip, close all rads before you start as this will save some water and any treatmen already in system, you will need to keep topping the combi up as the pressure will fall as you bleed the rads, make sure you finish with the pressure on the combi at the leverl recomended by manufacure, normally 1 - 1.5 bar. You cannot remove the rad valves without part draining the system to remove the pressure.
