Hybrid Car – More Fun with Less Gas

Solar hot water install uneconomic if heat pump installed ... opinions please ... - Page 6

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Posted by Alan C37 on October 17, 2006, 1:19 pm

That price is about ten times as much as here.  I wonder why.  You might
like to look at http://www.airlux.ca/  to see what is available.  I do
realise that it is not a ground source heat pump but it does seem to work
with a positive COP down to lower temperatures than you would encounter in
most of the UK.  I do know that similar units are in use in parts of Canada
with great success.  Mitsubishi make good modern models too but these are
significantly more expensive.  These are generally not "central" units and
do not need an expensive duct installation.
  Alan C

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Posted by news on October 17, 2006, 3:00 pm


I see heat pumps 5kW  @ 1100, 9kW @ 2100 plus the installation so it
depends on who does the digging but I reckon I could do it for less than
less than 3k... mini digger for the weekend is about 200 and the plumbing
will depend on circumstances
as to running costs -

The best gas condensing boiler has a seasonal efficiency of

approximately 85% compared with an efficiency of about 73% for

a conventional boiler. Heat pump systems, however, can operate

at seasonal efficiencies greater than 100% and an efficient GSHP

will operate with a seasonal efficiency of at least 300%.


Posted by News on October 17, 2006, 4:51 pm

Nope.  92%

Condensing boilers run at say 0.9 COP "overall".  A heat pump may be only
averaging say 2.5 COP - they advertise peak COP.  The peak of a condensing
gas boiler may be way over the 92% average.   As electricity is about 4
times the cost of natural gas in the UK, then the natural boiler wins out -
the local comparative fuel prices around world are what matters when making
these decisions.  Expensive to run COP 1 immersion heaters may have to be
used in the depths of winter to top up the heat pump.  Even if the heat pump
and natural gas boiler was the same running cost, the capital cost of gas
boiler wins out.  Then there is the capital cost of installation. Good
boilers cost less than 1K.

Heat pumps can be great off grid, but a comparison of capital cost and
running costs vs, oil, LPG, wood, etc has to be made. This is not an arm
waving decision.

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