Strange Radiator Valve

[Our Gee]

Two of my domestic (Bungalow) heating system radiators have strange (well to me at least) valves fitted. I believe that these where fitted when a new boiler was installed about 10 years ago. At the same time all my other radiators had Thermostatic valves fitted.
The valves in question are small body 15mm 90 degree type with a plastic screwed cap which can be un-screwed to reveal a small metal "plunger" which is about 6mm diameter which protrudes about 10mm out from the valve body.
It would appear that screwing the plastic cap onto the body eventually pushes down on the plunger which is then pushed into the valve body.
I can't find any info on this type of valve or what it does.
Any advice much appreciated.
Thanks

 

[Deleted member 120897]

Pictures often speak louder than words, but it sounds like lockshield valve.

 

[Basher]

Two of my domestic (Bungalow) heating system radiators have strange (well to me at least) valves fitted. I believe that these where fitted when a new boiler was installed about 10 years ago. At the same time all my other radiators had Thermostatic valves fitted.
The valves in question are small body 15mm 90 degree type with a plastic screwed cap which can be un-screwed to reveal a small metal "plunger" which is about 6mm diameter which protrudes about 10mm out from the valve body.
It would appear that screwing the plastic cap onto the body eventually pushes down on the plunger which is then pushed into the valve body.
I can't find any info on this type of valve or what it does.
Any advice much appreciated.
Thanks

Sounds like you have a "decorators cap" on a valve that would normally be fitted with a thermostatic head.
The screw down cap is basically an accessory provided with the valve so you can isolate the radiator to paint it, or remove it etc. It's not intended to be used for adjusting the radiator temperature in normal use - it should have a thermostatic head.
You could try unscrewing a thermostatic head from another of your radiators, and see if it fits this one. If so, buy one of those!

 

[Our Gee]

Thanks Basher,
Spot on, that's highly likely what I have. Looks like the Thermostatic had had to be removed to allow fitting to the radiator which is mounted very close to the wall. This Rad is therefore operational without the "Dial Heat" facility offered by the now removed "Head" which I can live with.
Thanks again.

 

[Ric2013]

Some manual wheelhead valves work on the decorator's cap principle yet aren't actually decorators caps. Never come across one in the UK but here is one in Italy:



Going by the rest of the installation, I can only assume these were very cheap. That said, the valves have been in for over 20 years and have not caused trouble. The radiators are much older.

 

[Ben-gee]

Used to get a blister pack , I think called conserv8, had thermostatic valve and lock shield - the valves were identical and the lock shield just used a decorators cap (which of course some customers fiddled with and upset the balancing!)