Please define DHW thermostat?
There are two thermostats specifically relating to the hot water.
1: An overheat thermostat positioned by the DHE
2: A temprature dial on the front of the water section
The first is very simple
The second will be stuck through scale (not moved since it was installed), if you try to move it, it will most likely start to leak through the gland. If you want to change it, change the water section.
If it helps, changing it will just be wasting your money, it is merely a water throttle that slows/speeds up the flow of water through the valve, cheaper and easier carrying out this throttling at the outlet tap.
Carefree, February 2011
