Draining central heating without a drain point....

[Malutki]

Hi,

This may be an incredibly stupid question so apologies if it is!

I’m planning to refit my bathroom soon & part of it is to fit a towel radiator. I’ve got an ancient Glow-worm combi & I know I need to drain the central heating system while I do the necessary pipework. Problem is, I don’t seem to have any drain point on any radiators upstairs or downstairs (unless its been conveniently hidden under the floor somewhere). There’s one radiator downstairs in the kitchen that has a twin entry valve, is it possible to drain the system by removing the blank plug at the other end? My theory was to shut off the radiator, drain it through the other end, then open the valve slightly & allow the system to drain that way. I appreciate it could take a long time & I’d only have to be careful to open it very slightly to control the flow out but I don’t have any other ideas.

Or is that complete rubbish & there’s a much easier, obvious way?

Thanks very much.

 

[landyandy]

That seems ok

 

[JohnD]

once you have drained it the hard way, fit a drain cock or a rad valve with intergral drain, for next time.

BTW if you have modern combi, or many other modern boilers, it will usually be sealed and pressurised, with no Feed and Expansion Tank in the loft, but it will have a pressure guage and a filling pipe near the boiler, and on these, you can undo any one connection or rad valve, and very little water will come out because it is sealed.

If you open two or more points, at the same time, it may come gushing out.

This doesn't work if you have a feed & expansion tank, as it is open-vented so will gush out whenever you open a drain cock

 

[Happyplumber]

Just pop into bnq and buy a manual drain off which you can cut inline,nice and simple ,drsin the system down and once you have finished remove the temporary drain off and solder one in its place

 

[tdesnos]

my usual method is: isolate a radiator, then crack the nuts on the valvw where it goes into the rad and put empty ice cream tubs underneath them, then open the bleed valve to allow air in and then decant the water into a bucket. Once the rad is drained, you can take it off and then attach either 3/4" or 1/2" flexible tap connector to the valve and the other to a hosepipe then simply open the valve and drain!

 

[holty]

the sugestions given are good examples.with your twin entry though likely to be microbore, the action your on about taking is spot on.johnD is on the right lines.simply buy an 1/2" male drain off valve , instead of the usual 1/2" plug.

 

[Gasman81]

tdesnos method is the easiest and also the quickest. then when you finished just change one of the downstairs lockshield valves (the one on the radiator closest to an external door) for a drainoff lockshield.

 

[holty]

proberbly quicker yes,yet having the drain off for the future, is proberbly better.

 

[holty]

sorry gasman81, just actually read your post.

 

[rojaca]

I'd go with Holty as tha was what I was going to suggest unitl he came up with it, though you are going to have to loose the charge pressure out of the system first- you'll probably find a drain off point on the blr to do this- when done close drain off first then take out 1/2" plug and fit 1/2" DOC.
Be sure to drop the pressure first though mind, and close the drain off you use. Otherwise you'll have two open points!

 

[Malutki]

Many thanks for all the replies, trying to scope out some potential pitfalls before I start. According to the boiler instructions theres a drain point on the isolating valves, its a small screw (couple of mm) will this be what I want to release the charge pressure?

 

[namsag]

OLD combi dont touch the isolating valves they will leak.

Go with Holty its the easiest and most sensible..... just turn off the rad valve if the return wont or cant be turned off on valve dont worry as you wont get too much out untill bleeds are opened.

Mind towel rad can be fitted with systen full but thats another method