In message , John
Rumm writes
On 21/02/2019 19:13, Andy Bennet wrote:
On 21/02/2019 18:52, NY wrote:


(*) I presume it does, since you say that it replaces your wet system.
No, it was to replace our existing boiler and couple up to our
existing wet rad system. Problem is we would need a 16kW output
system at high temperature. To get high temperature (up to 80C) out
of a air source system you need a two stage system, one outside air
heat exchanger plus a further heat pump indoors to raise the
temperture further. The outside unit is quite a large two fan unit.
We were not convinced it would be quiet enough. Plus it needs a firm
concrete base to stand on. All things considered a very expensive install.
The most efficient system is a ground source heat pump but this is
just too cost prohibitive for a retrofit system. I guess it would be
more suitable for new builds.

Less useable in high density housing though... as with many "green"
projects they are good for virtue signalling if you have spare land and
money.

Bore hole rather than a buried slinky pipe perhaps. You need a water
body within reasonable reach. Developer is considering it for a 4 house
development here despite mains gas across the lane.

All things considered it was a toss up between a high cost install
and cheap running, or a low cost install but more expensive to run.
The electric boiler won hands down purely on replacement cost, low
maintenace, low noise and a unit smaller than a gas boiler.



--
Tim Lamb