Best electric heaters for reasonable price - recommendations please

[SteamyTea]

There is, in thermodynamics a term, exergy.

 

'Exergy is a thermodynamic concept representing the maximum amount of useful work a system can produce as it reaches equilibrium with its environment, essentially a measure of the quality or usefulness of an energy form'

 

You can think of it as usefulness. So take a DHW cylinder, cold feed is at 10°C. When heated up, the mean temperature may be 50°C.

But the bit of water at the bottom quarter may only have a mean in 25°C.

Now I don't know about others, but a 25°C bath or shower does not appeal to me much.

 

Our combustion heating systems are similar, there is always hot flue gasses leaving somewhere.

Electrical systems are the same, but it depends where you measure and compare it, at the source or the load. Can make quite a difference. This is why voltage drop is important.