Yearly kWh for an average flat / immersion heater expense

Gerry1

PJ2000 said:

We also have an old economy 7 dimplex storage heater which isn't much use

Start by doing the Storage Heater Sanity Test.

Scot_39

Chrysalis said:

Scot_39 said:

Sounds like too low a hysterisis.

Thought immersion thermostats  had a good few degrees deliberately to prevent that frequent switching behaviour - in past iirc as high as 8-10 C

One of the advantages of having a smart meter, can see what is actually happening.  Not all immersions may behave the same as mine,l but I have no doubt if you running an immersion for an entire off peak period, the obvious way to save energy is to add a timer and only let it start much closer to the cutoff time.  Maintaining temperature still costs energy.

But the whole point of hysteresis is you don't need to maintain the temperature that accurately.

So if had an old higher hysteris thermostat in the 8-10C range - for a HW tank - 60 in reality might by on until 62 off then back on only in low 50s.

Enough of a gap to say reflect 24hours energy loss - or enough to rinse hands a couple of times overnight - without re-triggering the heating element.

GCH old style more likely to be +/-0.x degrees - and smart ones have predictive controls and often boiler throttling to reduce power to reduce overshoots etc.

Chrysalis

All I know is my immersion seems to use about 1/3 of energy still to maintain temperature, and have reported it here to help others.  Based on that buying a timer is a no brainer.

Spoonie_Turtle

While not the same setup (we have a heat pump), I changed our hot water to only kick in during set hours rather than all day, and it about halved the kWh usage for DHW.  It's possible some of that difference could be due to a warmer year (i.e. warmer incoming water) or very slight changes to usage habits, but we haven't had any drastic changes of habits. 
[Even if the timer 'only' reduced it by, say, a quarter, that's still significant in my book.]