ground source heat pumps

R measures insulation, U measures conductance U value is thermal conductance in W/m^2k (watts, metres square, kelvin)

R value =3D 1/ U value

Normally with GSH one doesn't abstract any water, one just takes the heat from the water.

NT

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

How is that calculated? Per site, per pump, per pipe into the river?

Would you really have to tell them? ;-)

Owain

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.

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.

Regards Bruce

He said that 20m3 a days needs no licence.

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.

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.

It can be done that way, or the well water can simply be left where it is and heat harvested from it by conduction/convection

NT

ck.http://www.ebuild.co.uk/forums/messages/3322/17635.html?1208929618Interesting idea. But I think the assumption that the same amount of heat will get extracted when all the pipes are bunched up close is rather unrealistic. On the plus side the concrete used could contain a high percentage of hardcore if the top of the cage is left open.

and out again, then I would assume he can pump as much as he > wants.

so much for assumption

NT

I have posted an enquiry to the EA on the basis that they would be informed by the planners if I specified using part of their flood plain to extract heat. Secrecy is not the way forward!

The slinky system can extract about 1kW per 10m of trench but my uncalculated guess is that a huge system would be needed to supply the heating energy for 200m2 of buildings.

ISTM that pumping *river* water from the gravel beds in the land next to the bank should give a clean supply not full of fish or blanket weed. Extracting the useful heat using DD's heat exchanger and then returning the chilled water some distance from the source should give better results than the usual pipe in a well. The slinky pipe has to be filled with anti-freeze leading to ground water contamination risks although I understand this can be brine.

As this project is right on target with current govt. thinking, a licence might be forthcoming anyway:-)

The waste can feed an ornamental fountain.

regards

heat will get extracted when all the pipes are bunched up close is rather unrealistic. On the plus side the concrete used could contain a high percentage of hardcore if the top of the cage is left open.

If I can correctly remember my schoolboy physics from 50 years ago, it goes like this:

I don't know how much heat is needed to heat your 200 M^2 offices - but it's almost certainly more than 4.8kW. [The heat calculations for my *house* come out at over 10kW in the dead of winter]

You need to do a heatloss calculation for the offices - taking account of all the areas, U-values, air exchanges etc. - just as if you were designing a central heating system (which you *are* really). If you can get hold of a copy of the Barlo or Myson heatloss programs, they will help - otherwise just do it in a spreadsheet.

Specific heat capacity water 4.187 kJ/kgK

Interesting - but how many of us have bedrock 2m down?

For the cost of some hardcore one can make a shallow underfloor void to suck coolth from too. Only requires a fan and heat exchanger.

that would cause it to freeze where it crosses, putting the system out of action

so much for assumption

NT

Our offices (400m^2) take *no* heating, even in winter - with one or two PCs per person, there's plenty of heat to go round.

On the other hand, a decent GSHP can cool on the cheap as well...

Also, my (average sized?) 3-bed semi has two floors of about 10mx9m each

- so his offices aren't that much bigger than my 180m^2.

Interesting - but how many of us have bedrock 2m down?

I think you have a basic misconception.

Ground source heat pumps that use water as a heatt reservoir take the heat, not the water. The primary curcuit is antifreeze loaded water in a closed loop.

That loop is generally buried in the ground, but it can be laid at the bottom of a pond.

Drivel is completely wide of any mark here.

Ignore him.