water too hot.. valve gone?

[freeflyer]

hi all

excuse my terminology, i dont know what things are aclled.
Anyway, got a standard heating system, boiler, tank in airing cupboard etc.

When the central heating is on, the hot water temp rockets (when i last checked it was 60+ degrees odd, thermostat set at 40-45). But, during the summer when the CH isnt on, it levels out at the right temp ie 40 degrees.

I'm thinking the switching valve may be gone, and not turning the supply to the tank off? We fitted a new thermostat so i know its not that.

 

[namsag]

Yes motorised valve is passing and allowing water in cylinder to get up to what ever temp the boiler stat is set to.
New valve required

 

[freeflyer]

Great.. thanx its a honeywell 9033, is there a bolt on replacement available do you know?

 

[freeflyer]

latest.. when i adjust the thermostat on the tank, i hear whirring sounds from the valve, and the water seems to stop flowing, and sounds like its backing up and changing direction. The little lever sticking out from the valve does not move.

Does this sound like anything obvious? motor, or perhaps the valve itself? it certainly seems to be doing something, just not sure if its right.

Oh, and its a V4073A .