Lockshield valves

[billybookcase]

I've been reading about balancing radiators by adjusting the lockshield valve, but they all go on about taking the cap of and turning it with a spanner.
Mine says Cresta Lux and has a + and - sign on it .
Am I right in assuming + will increase the flow and - reduce it?

My radiator is cold at the bottom in the centre of the radiator.

Or does this suggest sludge?

Boiler is a combi.

This is happening on 2 downstairs radiators.

 

[John506]

That it signs on sludge, but if you want to try balancing then if the lockshield plastic cap is corrugated for grip, then I'm guessing it will close and open the lockshield.

Clockwise to close the valve off, Anti-clockwise to open the valve.
(Righty tighty, Lefty Loosey)

 

[billybookcase]

Thanks.

 

[Master of None]

Dont count on the cover adjusting the lockshield. I have hattersley valves and the lockshield cover has + - on it but it does nothing but tell you which way to turn the screw under the cap. It is also the very same cap they supply with TRV valves to give manual control before the head is fitted.