Typically, a domestic hot water system which will provide enough hot water for a 3 bedroomed 3-5 occupancy household costs circa £3,000. (subject to free survey).

Savings

You can expect the following savings…

Gas boiler with an electric shower you can save
£180 – £350 p/a

Oil boilers – you can save
£320 – £380 p/a

Electricity hetaing / boiler – you can save
£500 – £750 p/a

To calculate the above we used the below assumptions

3 – 4 occupant household

18kw boiler heating water for 1hr per day

Gas        4.7 p/kwr

Oil           6.2 p/kwr

Elec        12 p/kwr

390w Thermodynamic system compressor running 12hrs p/d