Advice on draining home central heating system

[garry63]

Hi funsters
Hope you don't mind this post as not mh related
Are there any plumbers in the group that can advise how to drain central heating system so as to alter some pipe work.
I'm competent at doing pipes but not sure on safe way to drain system then top back up

 

[Mark McG]

Starter for 10 = depends on your system - we have a header tank in the loft which will need the water switching off before draining - I found a wine cork also works as a suitable bung in the tank feed pipe to the heating. When refilling system will need bleeding and possibly an approved additive adding back into the system- Ww have a Worcester boiler and needed this Adey-mc1-central-heating-inhibitor/p81125. - Plus what Figaro said

 

[Figaro]

Not a plumber but I've done mine a few times.
Stop it refilling at stop tap or local valve.
There should be a drain cock at the lowest point on the pipework with a connection for a hosepipe. Open valve and it should drain down.
There may be more than one drain cock and this won't drain the hw cylinder if you have one.
Open an air bleed valve on top of radiator to check the system has drained.
Refill is a reverse. If it's a combi boiler there is usually a refill loop to open and re-establish the pressure.

 

[St3v3]

Turn the heating off.

If you have tanks in the loft you need to shut the feed off to the small one, or tie the ball cock up.

If you have a combi make sure you know how to top it up and have the necessary key (if applicable)

Connect hose and drain. After a while, when the flow stops/slows open all of the bleed valves upstairs. Repeat for downstairs.

Filling can be complicated by the HW/CH valve if you have one. You need to make sure there is water in the pump before you turn it on.

Bleed the rads.

Call a plumber when it all goes wrong

 

[St3v3]

- I found a wine cork also works as a suitable bung in the tank feed pipe to the heating.

Like putting your finger over the end of a straw, then taking it out or the drink, that will keep water in the pipe.

That can stay there until you cut a pipe (allowing more air in than jusf the bleed valves) and then come out and surprise you.