Radiator stuck in closed position, turn dial to 5 and nothing happens due to crack in the lower TRV,

Thinking of replacing the top part if I can with this

http://www.screwfix.com/p/15mm-angled-trv-white-chrome/60368

Can I undo the silver knurl to remove this or does that = flooded kitchen? 😆

As long as the thread is the same you should be fine. I have heard horror stories about the pins popping out of TRV bodies but that’s from guys that change them day in day out so yours should be fine.

Yes, the large knurled nut will unscrew and release the plastic adjustor. Basically under that there is a plunger valve that just regulates the flow to the radiator to control the temperature. I’ve removed this item on one of my rads as its knackered. I need to get round to replacing the whole valve.

Nope, shouldn’t flood. Might be worth “exercising” the metal plunger bit underneath through its full range of movement whilst you’ve got it off…..