Central Heating Problems.

[Tilly2]

Why, when all but two out of the five upstairs radiators turned down to frost stat, are they all blazing hot?
The bedroom is like an oven!

Any help, please?

[Etch]

The thermostatic valves have probably stuck in the fully open position.

[Tilly2]

Can I do anything about that Etch?

[jno]

far be it from me to suggest your house may be on fire...

This might be some help?
https://www.diynot.com/diy/threads/thermostatic-radiator-valve-stuck-on-full.459084/

[Tilly2]

Thank you, Jno. That is really helpful.

[Etch]

Tilly2 - yes, if it is a stuck valve then it is fairly easy to fix. The usual problem is the valve sticking in the closed (off) position, but the method of dealing with it is basically the same. This video should help:

[New Judge]

Certainly TRVs being stuck open is a possibility. However, certainly with Drayton TRVs that is virtually an impossibility. Turning them down (i.e. colder) involves the control knob screwing the valve down against the spring and if the valve was stuck open you would not be able to turn the knob (certainly not without damaging the mechanism). The usual fault with Drayton TRVs is that they stick fully closed - i.e. the spring mechanism is not strong enough to return it to the open position against the corrosion or whatever is preventing its release.

It could be a fault with the body of the valve itself. It detects temperature and closes the valve when the desired level has been reached. But it would be very odd for the same fault to appear on two separate rads. If you take the body of the valve off the valve will be fully open when you do this. You should see a brass pin in the middle. This is the top of the actual valve . You should be able to push this down manually (though you will need the flat of a screwdriver or similar as the spring is very strong). If you cannot it means the valve is stuck open.

[Tilly2]

All the valves are Drayton, NJ.

It seems odd that three are malfunctioning at the same time.

A job for Homeserve, I think.

Thank you.

Etch, thank you too for the video. That was also very helpful.