Heating fine but only lukewarm hot water

[Bazwaldo]

Just recently hot water has become very cold to lukewarm. Remembered similar problem 2 years ago which was diagnosed as the motorised 2-port valve.
Tried manually switching valve into manual from auto and this seemed to cure the problem however it seems a little intermittent.
Replaced the valve motor on the honeywell but once again this has not cured the problem. Get plenty of water out of the hot tap but its just not that hot.
Could the problem be the valve itself or could it be a stuck thermostat ?
I have a Drayton Tapstat cylinder controller on the hot tank.

Can anyone advise ?

 

[oilhead]

The Drayron Tapstat is a direct acting thermostatic valve. Take off the head and make sure the valve operates(i.e is the pin loose and spring loaded?)
Are you sure the motorized valve is on the DHW primaries?

 

[Bazwaldo]

Firstly thanks for the advice.
I removed the head as you said and the pin was well and truly stuck. After some gentle persusion with a hammer,WD40 and pliers I seemed to have released it. Don't know if totally but it is definitely has some movement now. It must be doing something because the return pipe exiting the tank is now getting hot whereas before it was cold. Looks like I will be replacing the tapstat on the weekend then. Can't believe how expensive they are. I was quoted £70+vat.
Once again thanks for saving the day.