Replacing piping to radiators: how do I drain system?

I would like to replace the piping to some radiators to improve its appearance. My system has a Worcester 24i combi boiler and uses 10mm piping. I have a wall-mounted thermostat. Most radiators have piping that comes down the wall to them. There is no draincock on my system. I would be grateful if someone could read over what I am planning to do and provide comments, as some stages I am a bit unsure of. I am totally new to central heating, so please be patient. Here's what I have planned:

1. Turn off boiler on front panel. Turn off wall-mounted thermostat.

2. Turn off mains supply to boiler. Not too sure how to do this as there is only one water stopcock in my house. Do I simply turn this off?

3. Turn off electricity supply to boiler at mains board. Check light is out on boiler.

4. Isolate lowest radiator at both ends. Remove thermostatic valve, catching water that will escape. Attach valve with drain-off to radiator. Attach hose and drain off by opening lockshield valve.

5. Open bleed valves on all radiators until system fully drained.

6. Replace pipework.

7. Turn Mains supply back on (after closing bleed valves).

8. Turn electricity to boiler back on at mains board.

9. Turn boiler on and turn wall-mounted thermostat to full to re-fire boiler.

10. Re-set thermostat and boiler temp.

My system also contains Sentinel X100 inhibitor that was put in in January 2003. Will I have to do anything different because of this? Would it be wise to replace this, and if so how would I go about it? Thanks for any help.

sounds right to me on quick read thro.

u might want to use x400 for some time before u work on the system to clean it....

when u empty the system it wont contain inhibitor anymore cos it will have gone down the drain!

u will need to put in some inhibitor.

when u fill up, u will need to flush the system. use some system x300 . then empty and refill with some inhibitor....

to put in it undo a rad bleed valve ?
place it in the f and e tank, making sure it all goes down the pipe
take a rad off and use a funnel down the pipe (with rad valve off)(if u leave it attached to the rad and close u minimise black oxide spillage)

Sorry.... what is f and e tank? Which pipe do I put what down?

yeh what f&e tank

Worcester 24i probably has a filler loop

just turn the boiler off at switch. lock all the rads off to keep the inhibitor still in the system and obvious u dont have to drain all the water if its still in the rads and drain from one rad as youve mentioned

I need to replace the piping though, so I will have to drain the system won't I? Can anybody reply to my original post in a slightly more coherent manner please? As I stated originally I am completely new to central heating, so I can't really understand abbreviated/ grammatically incorrect sentences.....

hey up GSte.

It may not be abbreviated/ grammatically incorrect sentences.....

But if you can't work out you have to get the water out the system or you will get very wet

What the hell chance have you of putting it all back safely and in the right order

doitall said:

hey up GSte.

It may not be abbreviated/ grammatically incorrect sentences.....

But if you can't work out you have to get the water out the system or you will get very wet

What the hell chance have you of putting it all back safely and in the right order

Click to expand...

Did you read my original post? Obviously I know that I have to drain the system, my question is how do I do it correctly? But replies that say things like 'flush system with x300', 'use the filling loop', etc aren't much help. If I don't know how to drain the system, how am I going to know how to flush it, or how a filling loop works?

What chance have I of putting it back together safely? That's why I posted here in the first place, for help/advice!

so i miised it was a combi , big deal !

I didn't mean 'what f & e' like: 'what do you mean. its a combi!'......

When I said 'what f & e', I just meant that I didn't know what an f & e was!

Thanks for your advice, it was certainly the best I have received so far.

But I'm still confused as to how I flush the system..... do I just leave the hose attached, and after I've replaced the pipework, turn on the filling loop and let it flush through....?

Or do I fill the system then drain again immediately?

Once again, thanks.

x300 is a flushing agent that you inject into the system and allow to circulate for aa few weeks prior to draining the system.

The Filler loop is what you need to fill it back up again, I would find that before you do anything.

You drain the system through a draincock after you made sure the boiler and all the electrics to it are isolated, once the hose is running you open the air vent on the highest rads first to let the air in, and remember to turn them off again after all the water is out.

Flushing the system can be with a machine or fill and drain a few times.

Finally when its all filled and tested inject an inhibitor into the system

Thank You.