Draining pipes to replace leaking isolation valve

[renvo]

Hi, I need to replace a leaking isolation valve on the hot water pipe to the bathroom sink. The bath supply also runs off the same length of pipe, but I can't see any other isolation valves on the supply from downstairs, so assume I'll need to turn the water supply off at the stop tap then run all the taps to run the water out of the pipes. I have a combi boiler. If I unplug the power supply to the boiler before turning off the water supply, is there anything else I need to do?

Then, turning everything back on, I assume I turn the water supply back on, then plug the boiler back in? Should I expect to need to top up the boiler pressure?

Thanks for any advice.

 

[terryplumb]

You can turn off the mains cold water stopcock ,or on the boiler close the mains cold water inlets isolation valve. Isolate electric to boiler and drain hot taps.
Once done ,turn on cold water,and electrics supply to boiler.
Pressure on boiler gauge is irrelevant ,not affected.