Draining and refilling central heating system

alphazulu

I have an old central heating system (boiler on floor) and I plan to add a couple of new radiators to the system. I have the boiler on the ground floor and upstairs is a hot water cylinder and another small cylinder on the wall (expansion tank?). I had a look in the loft and there is a tank up there that is no longer used. I plan to drain down the system, take all the rads off and flush them with a hose and then add my two new rads.

Is this all I need to do to drain the system?

1. Shut off the mains water supply.
2. Switch off the boiler and programmer.
3. Attach hose to one of the downstairs rads and run it outside (all downstairs rads have drain points)
4. Open the drain valve and then open bleed valves on rads.

Then to flush the system I plan to take all the rads outside and spray water through them from a hose pipe.

Then connect my new radiators.

Then to refill the system do I just open the mains water valve and it will automatically refill or is there a valve I will need to open somewhere? When I refill I know I need to add inhibitor but is it worth running X400 or similar through the system for a few weeks first?

I plan to get a new boiler fitted in a few months when I start work on the kitchen but wanted to get it running as best as possible for the new few months.

squeekswhenwalking

you seem to have the gist. if youre going to flush each rad with a hose. then a cleanser prob wont do much, just use inhibitor, unless you want to break up sludge before removing rads you could run a cleanser thro first fernox F3 is good