draining down gravity fed c/h system

[wet wet wet]

Hello. I'm a novice diy'er and need some help....I need to drain down my gravity fed system but not too sure how to do it. I know how to connect to the drain off valve on the lowest rad but not too sure of isolation or shutting off the water? Do I need to isolate both boiler and the immersion/storage tank and turn off the water to my house or do I just need to go into the loft and tie up the ball/float valve in the h/e tank in the loft. Can I still have hot water in the taps while doing this. Please help and if so can you please list step by step in order that things need to be done....many thanks

 

[Dotty]

Why do you need to drain it down?

 

[heliotrope]

You must turn off your boiler and ensure it cannot fire up.

Isolate the supply to the f&e tank by turning off at an isolating valve or tying up the
ball valve to stop water entering the tank.

If you have spring return 2 or 3 port valves then latch the valves back to manual setting
(this will helpwith draining)

There is no need to drain the cylinder and you can switch on the immersion heater to
give you hot water whilst the system remains drained.

There is no need to interupt the water supply into the building.