Domestic hot water problem

[Vicario]

The hot water from the storage cylinder is far too hot. I turned the timer setting to 'off' three days ago and it's still very hot - hand burningly so. The cylinder stat is set at 60. I suspect that the water is at the same temperature as the central heating system; could someone guide me about what's the best way forward please. I have a Worcester Bosch boiler installed in 2020 and regularly serviced. Vented system with HW cylinder. The CH is fine and the flow temperature is set about three quarters round the dial. From looking on the forum I suspect a sticking valve somewhere - it can't be the thermostat can it, as I've turned the water controls to no HW. Any advice will be appreciated.

 

[muggles]

Is the immersion heater on?

 

[terryplumb]

Is the system Y plan ,(3 port motorised valve ) ?

 

[Vicario]

muggles - no. terry - not sure (just one big valve that I can see near the bottom of the cylinder).

 

[CountryFan]

Post a photo of the cylinder please including a set back one to include any valves etc.

 

[Vicario]

Will do that tomorrow. Thanks for the replies so far everyone.

 

[Vicario]

Here is the valve. There's a little pool of water around the big nut above the valve - is that normal?

 

[terryplumb]

No ,leaking water is not normal.
That looks like a mid position valve ,are there 3 copper pipes connected to it ? Can't quite make it out from your fuzzy picture !
That valve is very likely faulty and the cause of your problem.

 

[CountryFan]

There's a little pool of water around the big nut above the valve - is that normal?

No, it’s not normal. Can you post one a little further back to see the whole cylinder?

 

[Vicario]

Although the immersion heater is plugged in, it is switched off. Cylinder stat at 40 at the moment, HW is red hot.

 

[CountryFan]

Although the immersion heater is plugged in, it is switched off. Cylinder stat at 40 at the moment, HW is red hot.

Are you sure that’s the immersion? What’s the switch a little further down that’s switched on?

 

[terryplumb]

The clue may be in the "plugged in" reference?

Although the immersion heater is plugged in, it is switched off.

Does the valve connect to 3 copper pipes ?????

 

[Vicario]

Yes, three pipes. The lower box is the electrical supply to the various things in the cupboard (pump, water timer etc.) . The one on the wall is the controller for the wireless thermostat. The immersion is top left - a plug that is definitely off. (I leave it in disconnected as the wire dangles over the hot pipes if I remove it. The timer for the HW is downstairs next to the boiler and connected to the controller you can see in the cupboard.

 

[terryplumb]

Your motorised valve is stuck in the mid position.
Every time your central heating is running the hot water cylinders coil will also be heated.
Replace the valve.

 

[Vicario]

Thanks, Terry. Would that also cause the small leak through the nut above it? I was tempted to get my spanner and give it a turn - not recommended I suppose, especially if it's the valve that's the problem.