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Discuss Radiator Drain Tool Help in the DIY Plumbing How-To Guides area at


My boiler is a combo and all piping is plastic push fit. All of my downstairs radiators have a drain off cock. The issue I’m having is that I can’t find the correct tool to be able to open/drain the valve. I’ve been around plumb centres and they all say that they’ve not seen this type before and theirs are allen key types. I have attached a few photos which are not 100% clear but the internal size is very similar to a bleed key. It’s like I need a socket set but an extremely small one...



Advent Win
Radiator bleed key should fit. If it doesn't then it's probably because somebody's used something they shouldn't have and rounded them off.


Advent Win
Seen similar types in the past but looking at the other end pointing to the floor is that some type of slotted screw? Maybe the rad tail that screws into the rad is the wrong way up ....perhaps you could post up another picture...regards Turnpin:)
It's difficult to see from the photos and I might have got the scale all wrong, but that looks to me like a square end, probably 6mm across the flats. If so, it is probably the same key as goes with outside taps. E.g.

A set of baby socket spanners may also have what you need as one of the sockets.


Might one of these fit:
I find they tend to fit pump valves and some drain valves quite well. May be worth a shot for the price, think Toolstation has a similar item, possibly cheaper. Seem to remember using one on a slightly similar valve to yours.


Gas Engineer
Advent Win
Its the same size as the vent. You might find as there is dust etc. in the hole not much room for key. But if you file the vent key so its not chamfered on the edge, you will be able to get on the fitting.

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