Finally I have a problem for you guys.

http://blog.victorianplumbing.co.uk/...Tap-Chrome.jpg

Same function but different design to this one.
Right for temp and left for flow, pull for shower.
Even with the temp full HOT the water is barely warm.
Am I correct in thinking there's a washer/valve in the temp side that needs replacement or adjustment ?
Any advice would be great...

Cheers..

Assuming you have sufficient hot water at other faucets.
The temperature valve does not really sense temperature, it simply adjust the mix of hot and cold water.
Turn off water, remove mixing valve, turn on hot water briefly to flush valve.
Symptoms indicate blockage or debris in hot side.

Inspect valve while you have it removed, it could be a pressure balancing valve that automatically adjust for changing water pressure, but I doubt it. If so it may need to be rebuilt.

This is very similar to Grohe Temp Tub faucet ( see the pic )

Proceed as follows:

1. Make sure the handle is not loose as loose handle will give you false temp read out. If it is loose already than you have to remove it, adjust Temp as per thermometer read out and reinstall it.

2. If the handle is not loose, than you remove it anyway. Look at the tip of the stem to see whether it is not worn out allowing handle to spin w/o turning the stem. If stem is worn out, replace it.

3. If all appears to be in proper working condition than I suggest you remove the Temp cartridge and clean it under running water. There is a screen and when that screen gets dirty, it mismeasures reading.

4. Remove the cartridge, buy new one, and install it.

The last approach would be my choice as these faucets are very delicate and can get very easily damaged during service.

Back to you / Milo