The way forward?

I saw them fitting a ground source heat system to a new build energy efficient house on TV . They fitted quite large underground radiator system , not too deep possibly about 12 foot , and covered it with earth . I could not really understand where the exchange of energy came from to heat the system ? Is there any latent heat in the ground at 12 feet depth ?

 

There's heat in anything, as long as its above -273'C (or 0'K, aka absolute zero).

The heat pumps work on the principle that a liquid requires heat to evaporate, and that heat is released when a gas (or liquid) is compressed.

So by pumping a liquid through a pipe shaped such that it tries to form a spray, it has to evaporate in order to become the spray. It has to draw heat from its surroundings (in this case the earth) in order to evaporate.

So now its warmer than it was when it set off into the 'radiator' thingy. When it gets to the other end, the vapour is compressed back into its liquid form, and in doing so, releases the heat it took from the ground. Think of it like its a big sponge. You compress the sponge, stick it in the bath tub, let it expand (like the liquid in the ground source heat pump being sprayed to make it evaporate), it soaks up water (like the liquid soaks up heat), you then lift the sponge out, move it to where you want it, squeeze it (like the compressor squeezes the vapourised liquid) and the water you soaked up, or the heat you soaked up, is moved to where you want it.

Now imagine the underground network of fine pipes in this massive radiator thingy below ground. Imagine that its total surface area is many times larger than the total surface area of the inside of the compressor in your heating system. If you could imagine the heat absorbed from the ground as discrete units, although each one is not very warm, squash them all together in the compressor and the total heat is much greater. Enough to heat water to heat radiators, which in turn have a total surface area much smaller than the underground radiator thingy.

Speaking of radiators. The conventional approach in the UK seems to be to have a radiator right under the window in each room. It heats the surrounding air, which rises (because warm air rises) touches the relatively cool window, and much of the heat is lost. Not really very efficient even if everything is 'A rated'. But warm air rises, and the people in the room are invariably directly above the floor. So you put the radiator under the floor, and suddenly the best escape route for the heat is through the person that wants to feel that warmth. It has to get through the people in the room on its way to the relatively cooler window, and the ceiling. So you need to produce less of it for the same effect.

 

WOW!!! Where did you learn all this!!

 

It was elementary physics when I was at school, more than 25 years ago

 

Well explained Dave

Put your hand on the back of your Fridge Harry, that heat has come from the stuff in your fridge

When I touch the striplight in the caravan, its warm. Comforting on a dark rain & wind lashed night to think that heat comes from the Sun and the Wind

 

I knew that, just didn't want to get into the arguement about why I had to pay more for Dwr Cymru when I lived in Wales than Birmingham paid for the same water They weren't the ones that had to have it falling on them 24/7

 

@Zigs Surely the heat is coming from the motor?

 

No, the motor pumps the fluid around, the grill thinger is a heat exchanger designed to loose the heat from within the fridge