No hot water through shower controls

[Prezza]

I recently removed the shower controls below to try and find out why hot water has stopped coming through.
After taking it apart the only thing that I could assess might be the problem is a small pin which slides in and out some sort of narrow cartridge when the shower handle is turned. Can anyone tell me if I'm on the right lines, and can this small pin and cartridge be replaced (which would save me a bundle of cash)?

[/img]

 

[1godd]

Is the handle hard to move? Most common problem on thermostatic showers is the cartridge seizes up. If you can remove cartridge, i would use the aid of someone to turn water on quickly to see if anything comes through. If yes then you need a new cartridge. Can you get any details on the shower, if you can you wil be able to find it online.

 

[Prezza]

Hi there 1godd. The handle turns just fine. When I crank it round to the position where piping hot water should be coming through, the cold water pressure drops, presumably because it's expecting to be combined with the pressure from the hot water - but alas, no hot water.
Unfortunately there are no markings to tell me what the make is. I'll probably take it to a plumber's merchants and see if they can advise me.

Thanks for the reply.

TP[/quote]

 

[Googlyhead]

I think the second half of 1godd's post was implying you should check to see if the hot supply to the shower isn't the problem, rather than the shower valve itself.
ie. leave it dismantled, turn HW back on, and see if anything comes through.

If it's pumped; is the pump ok? If it's gravity fed, is there an airlock etc.

 

[TicklyT]

....Or maybe a filter gauze or non-return valve in the hot feed bunged up with limescale. As above, testing the hot supply with the cartridge removed will help locate the problem.

 

[Prezza]

It turns out the little thermostatic cartridge in the shower controls was sticking. I took it out and placed it in a shallow glass dish, submerged it in boiling water and very slowly the pin started to loosen up and eventually popped out. When I reassembled the controls they worked fine. How chuffed am I, that little cartridge may have been the smallest part but it would have cost a fair bit to replace.

Thanks for all the responses.

P