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Hi. We have just moved into a house with a oil fired heating system. When we moved in the cylinder thermostat and associated valve had no electrical supply. The water coming from the hot taps was extremely hot and heating seemed OK. I connected the cylinder thermostat (set to 60C). The thermostat itself seems to be switching and the drive for the mechanical valve is operational. I checked the valve moves realtively freely and put everthing back together. Next morning there was no hot water! By the evening there was (it has been sporadic ever since). I have subsequently removed the valve motor and placed the valve in a half open/half closed position - this seems to have remidied the situation for the moment. The water coming from the taps is now not as hot as before.
Any thoughts on why the thermostat and valve drive would have been disconnected?
Would this have caused the initially very hot tap water and the subsequent lack of hot water?
Do I need to change the thermostat, drive and valve and is this straightforward?

what type of system is it?, it may be that the microswitch inside the valve is faulty and not switching on the boiler and pump...(does the pump run when the valve opens. the valve may be passing allow the hot water tank to be heated when the heating is on ( this will give hotter water from the taps because the thermostat isnt having any effect on the valve

hope this helps. kev

Water is not getting hot.
I have a GLOW-WORM Central Heating Gas Boiler, with a 36"x18" Indirect Hot Water Cylinder. All radiators are getting hot, but the water in the hot water tank does not. The flow pipe from boiler is getting hot, but the return to boiler pipe is cold, or only slightly warm. This happened all very suddenly, weeks ago all was well. Thermostat was replaced and is working, but I used to operate without thermostat. The heating system has been flushed with FERNOX RESTORER, but not the HEATING COIL. What could have gone wrong ?
Greetings Eberhard.

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