Ian Stirling wrote:

I'm surprised nobody does a shower tray with one integrated.

The cost of recovery would greatly exceed any savings. It's a concept as
unviable as replacing an old reliable boiler with a modern less reliable
unit. On paper the cost saving is say £100/yr, but with only a 10 year
life, it's more cost effective to keep the old unit and pay more for
fuel. (but spend more on insulation)

Regards
Capitol