Owning your own home

it’s a complex question with different answers.
i have a modern unvented cylinder that is well insulated (a stainless tub that is inside an insulated sleeve) which is heated overnight with cheaper nighttime electricity as i’m on economy 7 so it’s reasonably efficient even though i’m keeping 125 lt of water warm at a high temp, if you like baths you can wash your hands/do dishes etc and still have enough for a bath at the end of the day. I shower though so have an electric shower, what i should have done is fitted a shower tap to the bath as well which means i could have easily got 2 showers a day out of the hot water tank and saved a few pounds a month by not using the electric shower.
what I don’t do is put the daytime immersion on as that will really cost a lot more and only warms the water a few ° which is unnecessary as the cylinder is so well insulated and hardly drops in temp through the day unless you decide you want a 100lt bath in the morning, modern cylinders have a floating baffle in them to help deal with the influx of cold water mixing with the hot but the laws of thermodynamics cannot be avoided.

whatever system you have it’s going to be expensive compared to current gas boilers and unless you don’t care about running costs you will have to think about how you use hot water.

If you have an old fashioned bare copper tank with with an insulation jacket tied round it then it’s probably worth having a new modern cylinder fitted as this will bring the cost down of having hot water.

So you can have a shower off an immersion but i would want an electric shower also as this means you can have a hot shower even if your dear partner decides they want to fill the bath to the brim with piping hot water and then leave it to cool down before they can get in it.....

long term we will have to wean off gas but electricity should be cheaper as the percentage of renewables grows and heatpumps become viable once homes are better insulated.