can be a can of worms i agree..
i dont usually touch the boiler unless im gonna be fitting new rads...
I find best way is to just turn the valves to the rad off...sounds simple eh?
pullin the rad off then is easy enough, provided theres 2 of you, you have a big bucket, and the carpet is well away...
turn it upside down soon as you can...
problems:
trv (thermostatic one, big plastic thing with numbers on)
2 things here, make sure when you turn it off it gets past the '*' (frostguard) to the '0' (off).
If when youve got the rad off, its p'ing out all over at pressure its probably foobar'd...some people stick a 5p in between the valve stem (metal bit) and the actuator(plastic bit), sometimes it works too..
i find best thing with these is to either screw a flexi tap connector straight to the valve end with a stop end on the other end, or just stick an olive on a bit of 15mm copper and a nut and screw that onto the valve with a stop end..that way the valve can do what it wants, itll never leak..
the lockshields (opposite end of rad) are usually fine but if you do get a drip repeat above..
The reason i use this method is i was caught out a while ago..
built extension for customer, removed rad for plastering the knock through area
window wasnt installed, just a plastic sheet over..
trv off, or so we thought..
gravity system (yplan, tank in loft, cylinder in airing cupboard)...
4 o clock in morning temperature drops to around 3 degrees...
trv opens to prevent pipes freezing...
when they open they open FULLY
system fills itself on gravity via ball valve in loft unless tied off...
flooded blokes house...
it was in the floor/ceiling/coving/studwalls...
wrecked his carpets....
1st thing anyone knew was about 7:30 when they all got out of bed...
public liability claim that one...