DIY ground source heating

 

Hi folks,
I've been thinking about a simplified ground source heating setup for
DIY and would value constructive and educated input.

You hopefully already know how ground-source heating works:
Water is pumped through buried pipes and fed through a heatpump to
concentrate the collected heat.

My simplified method would be to do away with the heatpump and water
systems and suck (not blow!) air through slightly larger diameter
buried pipes directly , with a constriction at the intake end.  Since
the air would be at a lower pressure inside the tube it would heat up
as it regains ambient pressure indoors (similar to how heat pumps
work).
The air would obviously be fed over the pump/fan motor to salvage heat
from that too.

(At daytime the air could be sucked through solar boxes which are
warmer than the ground would be, but my main concern is night time
heating.)

My rough calculations say that the low pressures achieved by a high
powered vacuum cleaner are adequate (remembering that degrees Kelvin
must be used for the maths). Obviously I don't plan to use a vacuum
cleaner for anything other than tests
but a purpose built vacuum pump.

So the big question is:
Could this setup approach the energy efficiency of an air conditioning
unit or existing ground source heating system?
Mechanically it would be a much simpler system to build and maintain.



The second idea is for a refinement to above:
Instead of sucking air through a constriction, how about recouping
that energy by powering a smaller air motor from it and mechanically
returning some energy to the vacuum pump?
In practice, the unit would be designed to do both, running on a
single shaft with the air motor being a slightly smaller capacity
version of the vacuum pump doing the suction work.

 

On 29 Jun, 13:55, markz...@digiverse.net wrote:

 

That would be "free" energy if it worked.  That's why it won't work.
You can assume that for all your diy projects that the laws of energy
conservation are still in place.

On Jun 29, 9:20 am, markz...@digiverse.net wrote:

 


Well no, modern heatpumps have an efficiency of 3+, meaning that for
every kw input they collect another 2kw's worth of ambient heat. I was
wondering if my simpler setup would be as energy efficient as a
factory built ground source system but much simpler.

 



I think you mean 3 kW, with a COP of 3.

Nick