How do I fix/replace this broken radiator valve?

opticks

As you can see in the pictures I've attached, the Drayton TRV4 valve on the radiator in my bedroom has snapped off and there are bits of plastic left inside. Since taking the pictures, I took off the metal ring and the bits of plastic fell off. Will I be okay to simply buy the head of the valve, as sold here - www.toolstation.com/drayton-trv4-classic/p39498 - and replace it, rather than buy a whole valve?

Thanks in advance.

opticks

(pictures)

bob_a_builder

Can't see a problem doing that -  BUT make sure that the pin on the fixed part of the valve still moves up and down ok - push it down with a screwdriver blade and it should come up again - if not it might have seized , try a drop of wd40 or similar on the pin to see if it can be got moving again if not then the whole valve would need to be replaced 

Jeepers_Creepers

As Bob says.

Remove all the plastic pieces from around the valve top, brush it all clean and then give it a spray of WD40 or - ideally - silicone spray if you have it. Get the pin and the top bit immediately around it especially clean. The pin will be firm to push down - it's quite a strong spring - so it'll hurt your thumb to do this so use summat to make that easier. It should go down smoothly tho', 'bottom-out' firmly, and then pop back up when released. If it does, it's fine. 

The new TRV head will have the chrome screw-down fixing ring on it - turn the head up to 'max', position it so's the number is facing out (so's it can be read...) and locate it on the valve - it should sit on in a defined position. Screw the chrome ring down all the way, but finish hand-tight only. The head should be firmly in place with no wobble. 

neilmcl

As above, completely unscrew the leftover part of the valve head from the valve and clear out any of the broken bits, then simply replace it with a new head. Just check that the pin can still move freely up and down.

DiddyDavies

If the pin does move, there is a possibility that it will push down and won't pop up again. This is because there is a very small spring inside the valve which pushes up on the pin and this spring can often get rusty or caked in muck.

If this happens, you may be able to loosen it up by tapping on the valve body multiple times. Tap very gently with something like the end of a screwdriver.
If it does stick down and tapping doesn't work, try gripping the end of the pin with a pair of pliers and work it up and down a few times.