Hot water functioning but suspiciously hot and a towel rail with it's own mind.

[Marti]

Good Morning Guys,
I'm normally over in the Electrician's Forum but my GCH experience normally stops at S and Y connections. Also, my old house was a simple, mains fed combi-boiler and I'm just moved to a place with header and hot water tanks so I'd appreciate your views. I'll call-in a GCH specialist to check and service the system once the Covid-19 is under control. for now I just need to check a potential safety issue on an otherwise perfectly functioning system. The hot water taps and showers (Salamander pumped) feels suspiciously hot With both the Drayton tank thermostat and the tank immersion element set near to minimum. Also, one towel rail appears to operate with the hot water timer rather than the other radiators; useful but odd (to me). I've added a couple of images to assist and the essential details are:

Worcester Greenstar R11
Salamander Pumped showers
Honeywell 3 way valve
210litre HW tank dated 2014 with five pipe connections
Drayton Lifestyle controls

I've got more notes and and I've labelled-up a couple of photos but didn't wan't to swamp the post; Let me know if I can clarify anything. Could be worrying unnecessarily but I have vulnerable family and so tend to service and care about the heating more than some. Your advice is appreciated.

 

[SJB060685]

Firstly the pipework in the cylinder is rough. I'm not sure on the minimum distances required for plastic pipework connecting to cylinder but I would redo that all in copper and properly laid out.
The HW temperature could be down to a dodgy cylinder stat not switching off at desired temperature and continuing to heat water to boiler stat temperature. A cylinder stat that has come loose from its position on the cylinder will also cause the water to be heated to a higher temperature as well, although from what little I can see it doesn't look misplaced.
Its not uncommon to have a towl rail coming off the HW circuit either.

 

[Marti]

Thank you. Going on your comments, I can start by pulling both thermostats, The immersion 'stat and the Drayton and testing with a multi-meter. The pipe work can be done, potentially with a new and more efficient cylinder if the thermal efficiency has moved on.

 

[Murdoch]

Hum ........ a very simple test to do.

Switch on hot water ONLY, adjust tank stat down until boiler stops running (remember most have over run these days so allow this to happen).

If moving the thermostat doesn't turn the boiler off then that is probably the problem.

Being a spark like you, I would then double check the tank stat by using my MFT

Hope this helps

 

[moonlight]

Firstly the towel rail is probably connected to the flow and return of the boiler so is hot when ever the boiler is on.
Secondly is your mid position valve letting by when you are just calling for heating? You can test this easy enough, when systems cold. just put the heating on feel the pipework going to cylinder if its getting hot the valve is not functioning correctly, and you will have no control on the temperature of the water when the heating is on.