On 21/02/2019 18:52, NY wrote:
"Andy Bennet" wrote in message
...
We looked at installing an air source heatpump, would have cost £13k
to upgrade our existing wet system.

So does it heat the rooms by blowing warm air (*) through vents in the
room? My parents had gas-fired hot-air heating in their house (installed
at new build in 1972) and said "never again": the house was always cold,
especially if you were in the draught of the floor vent, even with the
thermostat set high, and a lot of dust settled on everything despite
frequent cleaning of the air filter in the boiler. It cost a fortune to
run, even after we had cavity wall insulation; however I don't think the
house had double-glazing.

It was by far the worst CH I've ever experienced - even compared with a
single storage heater in my first house.

I would say that wet radiators (heated by whatever fuel is acceptable)
are the only realistic way of heating a house. How ever you do it, it
needs to be able to achieve the temperature that is required, and to be
able to heat a cold house (after a holiday) within a few hours.
Otherwise we'll all have to invest in Hive and other control systems
which allows the CH to be turned on remotely several hours ahead of
arriving home. Even our wet system, with a bloody big oil boiler (a box
about 4x3x3 feet outside), took about 3 hours to heat the house from 12
to 20 degrees in winter if we went away over Christmas.

I get the distinct impression that the government are banning existing
CH systems (as with ways of generating electricity) before they have got
a replacement that is at least as good. Replacing with something worse
is worthy of the strongest possible contempt.

I suppose modern houses can at least be insulated better than existing
houses are.


(*) 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.

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.