condensing boiler

[vince]

I have just installed a condensing boiler. As warned the extra pressure has resulted in leaks on some radiators. I am changing some of the valves and radiators that means draining the system. I have never done this on a sealed system and all questions result in - get a plumber. I thought it is easy to turn off the boiler stop the mains water and drain the radiators then just turn on the water again to fill. Plumbers tell me it is not that easy.?? Any experience.

[Doctor Drivel]

Turn off the power to the boiler (remove the fuse). Replace valves with good quality valves and rads. Fill up system using the filler loop to no more than 1 bar on the gauge. Remove air from the system. Check for leaks. Drain the system again to flush. refill. Remove air. start up boiler and ring to temperature. Check for leaks. If OK then add inhibitor. This can be injected in a rad (available from plumbing places).

Keep checking the pressure over the weeks and no lower than 0.5 bar and no greater than 1 bar. See makers info on the pressure it needs, which in 99% of cases is 1 bar when cold.

[John Rumm]