On Jul 15, 1:51*pm, "Doctor Drivel" wrote:
"BruceB" wrote in message
.. .
wrote in message
...
On Jul 15, 1:56 pm, "BruceB" wrote:
"NT" wrote in message
...
Normally with GSH one doesn't abstract any water, one just takes the
heat from the water.
But sadly, the environment agency consider it 'abstraction' even if you
put
it back again. So is you put more than 20m3 a day of say river water
through your heat pump then you would need an abstraction licence.
Regards
Bruce
I thought with a GSH pump you don't even move the water - the heat
pump pipes are a sealed system pumping coolant round the pipes. The
coolant is warmed up as it passes through the pipes which are immersed
in the groundwater, and that heat is then extracted in the building.
That can't possibly count as abstraction of water. I may be wrong
about the mechanism though.
***********
You are right, but the term GSHP is often used loosely. *Taking water from
a river I would normally call a water source heat pump. *More accurately
perhaps, we are talking about the difference between an open circuit and
closed circuit collector.
I was really making the point that even if you put water back it is still
abstraction.
The most efficient are water sourced heat pumps. Pumping ground water
through a heat exchanger and back to ground can do the same thing.
Extracting heat from a running stream is by far the best. *Water contains 4
time more heat per volume than earth.
You can have a plastic pipe run under the earth circled as in Heat Pump
slinkies. *But to improve matters run this pipe through a collection of
large water cylinders or plastic barrels above ground. Extract heat via the
heap pump at the hottest part of this system the storage cylinders . A
normal water pump would pump heat from the ground via the slinkies 24/7 and
dumps it into the cylinders, then the heat pump extracts the heat when
needed from the cylinders. *The heat from the surrounding air, heating the
water in the barrels has some gain too. *The mass of water in the
cylinder/barrels hold 4 times more heat than earth, so acts as a
concentrator upping the heat efficiency.
This is a slinky for a ground sourced heat pump, made from a concrete block.http://www.ebuild.co.uk/forums/messa...ml?1208929618- Hide quoted text -
- Show quoted text -
Here, eastern Canada the possibility of pumping water out of a lake
extracting heat from it and dumping it back was raised. But it was
pointed out that in winter, which is when heat needed the water can
freeze and go well below zero C!
The ground temperature however is generally around 8 to 10 deg C.
The temp. of the municipal cold water supply to our house, for
example, via a pipe some eight feet down is, even mid winter, always
in the range of 45 to 55 deg F. So ground loop heat pump systems
apparently work well. Seemingly; for in ground systems plastic conduit
is buried in ground somewhat below the frost line depth of around 40
inches, and a closed water loop is run through it.
Air heat pump systems apparently run out of steam, as it were, at
temperatures below say minus 6 to 10 C and just cannot extract enough
useful heat out of the outside air at those temperatures! So auxiliary
electric heating coils cut in in effect one has electric heating.
Electric heating is common here with most of the generation,
especially in this province by hydro.
The incremental 'extra' investment for even a simple heat pump system,
for a basic 1200 to 1600 sq. foot well insulated (as required by
building codes nowadays anyway) home here is rumoured to be in region
of $20,000+ Can. Roughly say 13,000+ UK pounds? That extra cost, in
order to be profitable or at least break-even, has to be recovered by
any savings in energy costs over a reasonable period of years.
For someon who installed basic electric heating some 40 years ago the
retrofitting cost, including some means of introducing the heat-pumped
heat, using an air exchanger of warm water radiators, into the house
would considerable!