Draining and refilling an unvented system

[scaffie]

I have searched and trawled this site and the net, but can't seem to find anything whihc explains how to do this.

I have an unvented system, and am gutting my bathroom at present.

I am now at the stage where I need to start changing tap/shower pipe locations, and plan to stick isolation valves just where the hot and cold pipes come into the bathroom so I can put the water back on and take my time to sort out the bathroom while using the water in the rest of the house as normal.

How do I safely drain and refill the hot water system to do this?

I can find the mains stopcock, and also a valve which if opened would rain into the pressure/expansion relief discharge pipe.

Presumably though, I need to "vent" the system to clear the vacuum to allow it to drain though(?)

 

[cjb1971]

wouldnt open the pressure relief valve if i was you,most of the time the will not re seat properly.

 

[Gasguru]

Shut off mains, open hot taps. That will drain most of the pipework, if you need to drain cylinder connect hose to drain-off valve at the base where the cold feed connects.

 

[scaffie]

Thanks. Preumably when I refill I won't have any pressurisation problems?

 

[cjb1971]

you wont be emptying the central heating system just the water in the pipework for your taps/shpwer etc-no need to refil-just turn mains water back on and open taps.

 

[scaffie]

you wont be emptying the central heating system just the water in the pipework for your taps/shpwer etc-no need to refil-just turn mains water back on and open taps.

Even with an unvented system?