Hi, a thermostatic rad valve is leaking slowly from the thermostatic plunger thingy under the adjuster handle/dial i.e. the thingy that has the small plunger rod which moves up and down, and is not leaking from the valve pipe connections (compression). The rad is downstairs and the supply pipes run down and straight back up the wall to this rad. There is a drain-off point in the pipes to this rad.
In case the plumber can not make it soonish is there a simple (not draining the entire system - pressurised) method to replace the valve or the widget that is leaking? I have a spare valve and looking at this see that the widget unscrews from the valve and has an o-ring, which I am presuming to be the source of the leak, or the seal on the plunger rod. Thank you, and Happy New Year.