Draining CH system to replace rad valves - please help!

[minimayfair]

Hi All,

I'm a plumbing novice, so I'm sorry if I'm asking something that would be obvious to someone more experianced.

I have a Vaillant turbo max combi boiler running my CH system and I want to drain the system to replace the normal valves with TRVs. I also want to take the opportunity to replace 1 old rad, flush the system and add an inhibitor.

So here's where my questions start

How do I drain the system? I cant find a drain on or near any of the radiators.
Do I have to do anything to the boiler when I drain it?
How do I refill the system? The vaillant says " make sue the flexible hose in connected" What hose and to where?
Any additional advice given the work I'm planning?

As much info as possible would be a great help

thanks, Chris

 

[WedgeAntillesRed2]

Turbo Max's usually have an in built filling loop which you should be able to identify by a grey handle. Just turn it and possibly another one connected with it 90 degrees to re-pressurise system after you have drained it. They are found under the boiler.
Not at all uncommon for monkey installers to neglect a drain off!
Heres how to do it :
1. Choose a rad you want to drain from (lowest rad in dwelling i recommend)
2. Pull back carpet, or use plenty dust sheets around one pipe end of rad.
3. Bleed off system pressure from air vent until it no longer dribbles
4.Turn off both ends of rad valves, and if possible put a tray under rad to catch any water. Only a caution as you have now theoretically airlocked the water in the rad.
5. If they are 1/2 inch rad tail connectors you are laughing, simply stick a hose on tail and open the other end rad valve. Go round all other rads opening the airvents, letting air into the system! Dont forget to shut them before filling up.
6. If there 3/4 rad tails i suggest draining the rad manually (catching it in a tray) then removing the valve from pipework and sticking your hose on the copper.

Boilers got an auto air vent BTW so shouldnt need to touch it

If only real life was as easy as plumbing ,lol

 

[minimayfair]

thanks for the advice, I'll give it a go.

Much appreciated

Chris

 

[plumberdan]

3/4 rad valve try putting the end of and outside tap on the valve, the nipple that comes off the tap, if you've got one of course.

 

[misterdubya]

As an addy, turn the boiler off before you start.
Put Inhibitor in when you re-fill.

Mr. W.

 

[namsag]

No need to drain it , if the auto air vent is visible screw the cap down.
Release the pressure at rad bleed or basin under cracked rad valve. The system will vacum up for changing one valve at a time.
Or turn off the boiler isolating valves for sam affect.

The repressurise when finished