Thermostatic Valve Needle

[Hardley26]

One of my radiators is cold at bottom and slightly warm at top
I realise that it is properly build up of sludge and I will flush the system out, but it was suggested that I first check that the thermostatic valve needle was working correctly, but I cannot see how to get the top off the valve to check the needle.
Any help will be appreciated.

 

[D_Hailsham]

Which make & model valve is it?

On most valves the head is held in place by a large knurled ring. You just turn it anti-clockwise as viewed from above. Set the stat to max before removing the head.

 

[Hardley26]

Thanks for your reply.
The thermostat looks to be a “M29 by ORKLi” it is very hard to see the make properly.
The only ring that can be turned by hand is where the valve is attached to the top of TEE piece; other parts go to radiator and return flow, I think if I undid this water would come out.
Having a closer look at this radiator I see that the hot water flow enters from the further end from thermostatic valve, cold return flow comes out via the thermostatic valve, but there is an arrow on the valve pointing towards the radiator, which seems wrong to me, do you think the Plumber fitted the wrong valve.

 

[D_Hailsham]

The thermostat looks to be a “M29 by ORKLi” it is very hard to see the make properly.
The only ring that can be turned by hand is where the valve is attached to the top of TEE piece; other parts go to radiator and return flow, I think if I undid this water would come out.

You can safely undo that ring and remove the head - no water will come out (set the thermostat to highest setting first). You will then see the pin sticking out of the valve body.

Press on the pin - it should go down easily; then release - it should spring up.

I see that the hot water flow enters from the further end from thermostatic valve, cold return flow comes out via the thermostatic valve, but there is an arrow on the valve pointing towards the radiator, which seems wrong to me, do you think the Plumber fitted the wrong valve.

Presumably you have checked which pipe is flow/return by feeling the pipes.

If the valve has only one arrow, not two at right angles, the valve has been installed incorrectly. It must be installed so the arrow points in the direction of flow, i.e towards rad on flow pipe and away from rad on the return. It does not matter which end the TRV goes, but at one end the head will be vertical and at the other it will be horizontal.

 

[Hardley26]

Thanks for that Info, I had suspected that the valve was fitted incorrectly.
Think I will go ahead and remove the radaiator and give it a good flush out.

 

[D_Hailsham]

Think I will go ahead and remove the radiator and give it a good flush out.

And either move the TRV to the other end or turn through 90 degrees, so the arrow is pointing in the correct direction.