Hot water conundrum.

[Jayh1986]

Hi. After many trips up and down stairs, I can't for the life of me work out what's heating my hot water. Have gas heating and hot water plus a backup immersion heater.

I have turned the spur off for what I believe is the immersion heater in the kitchen and to double check also turned off the switch in the airing cupboard which leads to the immersion itself. Leaving the spur on for the boiler but with the central heating and hot water turned off on the programmer, I am still somehow getting hot water.

I turned the boiler spur off and drained off all the hot water til it's only cold coming through. Turn on the spur under the boiler and I'm getting hot water again.

Anybody any idea how the water is still being heated

 

[Jayh1986]

Here's a picture. When the spur under the programmer is turned on the green pump is on in the airing cupboard. Immersion is definately turned off and water is getting hotter from the tap as we speak. Boiler not on.

 

[undertrained]

When you turn the programmer on is there any demand eg hot water or heating? If the pump is coming on then the motorised valve is asking it to which could also be an indicator and putting hot water into the cylinder/hot tank. Also that cylinder stat doesn’t look like it’s on properly, resulting in very hot water as there would be no control.

 

[ianmcd]

Turn both the heating and HW off at the programmer and see if the pump and boiler are still running

 

[oldbuffer]

1. You have a "combined" cold water cistern and hot water cylinder.
2. The hot water is heated:
2a. By the electric immersion heater, AND / OR (when immersion switched off) Controlled by thermostat inside immersion heater (with possibly an overheat cut out thermostat also inside heater).
2b. The gas boiler via the three way motorised valve (white, bottom foreground). Controlled by thermostat above an to right of immersion heater.
3. The hot water is stored, and it is almost certain there is insulation around the cylinder behind the plywood cover.
4. Because it is stored hot water, once heated it will provide hot water with all sources of heat off until it runs out.
5. If, with the immersion heater off, you are getting hot water again from a cold cylinder as soon as the boiler is turned on it is possible you have a combi boiler with one or more hot water outlets supplied directly by the combi.