Radiator drain valves

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I've currently got a drain cock fitted in-line in the tails to a couple of my downstairs radiators. These allow the system to be drained, but of course, not the individual radiator.

If I had these removed, and fitted one of these instead...

http://www.screwfix.com/p/angled-radiator-valve-drain-off-15mm-x/70408

...am I right in thinking that they still allow you to drain the system, but also allow you to drain the radiator only - ie if you close the radiator valves, undoing the drain cock on these valves allows water out of the radiator only? The only thing different to my current set up is that it wouldnt allow you to shut off the radiator individually and drain the rest of the system, although I have no idea why you'd want to do that.

Have I understood these valves right?
 
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Those drain off valves only allow you to drain the system,if you turn both valves off the system will not drain.
Pegler do a valve that allows you to drain just the rad by turning off the valves or both system and rad.
They are available at screwfix but I don't have a link for them.
 
Those drain off valves only allow you to drain the system,if you turn both valves off the system will not drain.

Do you mean if you turn both valves off then the radiator will not drain? The reviews seemed to say it would.
 
Danfoss do a drain off tailpiece that allows the rad to be drained but not the rest of the system. I fitted them to my radiators in case the missus wants me to reddocarate this week or next :D

Google danfoss drain tailpiece and you can see them

Graeme
 
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Graeme I presume with that one you can either drain the system or drain the rad only. I think that's what I'm looking for, although I thought that's what the one in the link I posted allowed.
 
It sits between the valve and the rad, so if you shut both valves it will drain the rad only. If you leave a valve open it will drain the rad and the system.

Graeme
 
I disagree with Armo74 in part. The valve the OP linked to will allow you to drain down the system to that level but they will also allow you to drain the radiator only if that's what you want e.g. to allow radiator removal for decorating. Operation of the valves will determine if you are draining all down to that level or just the radiator. What Armo74 seems to have missed is that the drain is connected above the valve seat within the valve.

To drain just the radiator the valve must be shut as well as the valve on the other end. If you have a thermostatic valve on the other end you will probably need to fit what is known as a decorators cap to keep the valve off. Only a few thermostatic valves have a full off position that means they do not require a cap to be fitted in place of the thermostatic head.

As said by others the only down side of using such a valve is pipework below the radiator valve cannot be drained by that valve. You should have another drain point at the very bottom of the system to allow the system to be fully drained which is useful when flushing out the system.
 
As said by others the only down side of using such a valve is pipework below the radiator valve cannot be drained by that valve. You should have another drain point at the very bottom of the system to allow the system to be fully drained which is useful when flushing out the system.

As it stands, this valve would be to replace a similar valve in the radiator tail which wont allow radiator only to be drained. So, I don't think I'd be worse off with this one. The seem to be dual purpose vs the older ones in the tail as with these you can drain rad only or rad and system. I dont think there's a lower drain point than that but it's a good point you make. Downstairs is suspended flooring. Is there likely to be a drain cock buried under the floor somewhere, or else all the sludge could sink to the bottom. I guess that's why powerflows would help!
 
You will usually find a low drain point under suspended floors - Getting to it is usually the problem! A typical location is through a trap in the under stairs cupboard (if you have one) or any other location deemed practical by the installer.
 
Those drain off valves only allow you to drain the system,if you turn both valves off the system will not drain.

Do you mean if you turn both valves off then the radiator will not drain? The reviews seemed to say it would.

Apologies, I obviously did not word my reply very well, what I meant was the system will not drain but the rad will.
What I was getting at was that I prefer the pegler ones and not the ones in your link as I have had one or two problems with them.
 

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