- Is it only applicable to people with a GSHP and with deep boreholes? Would the diurnial benefit help those with horizontal slinkies? How do I find one of these people? How can I find another GSHP user with a borehole? (Any volunteers, please email me!)
- Can this be done cheaper and quicker on another house, but with the same result? It's obvious that R+D, the making of the prototype always takes longer and costs more.
- Would the benefit be cost effective? Is it only 'helping the planet' but not helping the householder?
- Is it a technology that only I can do, or can I codify it precisely for others to follow? (including drawings and design details for the glassy boxes, in a way that Ice Energy or someone else could package up as a kit for plumbers)
- If starting again, wouldnt it be better to have a swimming pool sized polystyrene box or earth under the lawn or house, and store the heat in that!? So no borehole needed.
If anybody reading this is covered by my first paragraph, please email me!
Some Value Engineering needs to be done to quantify the benefits, against the possible installation costs of a system, materials and labour. For the benefits, this are many variables depending on the existing location, eg south facing or shading, depth of existing boreholes, heat loss of the house, operating regime and existing energy costs of the occupants etc. And the benefit may not simply be in the bills - it can reduce the installation capital cost of a GSHP. If it can reduce the depth of a borehole from 100m to 50m, that is saving about 2000 pounds! It might be able to remove the borehole altogether enabling one to charge up a horizontal array of underground pipes.
As the system works with a low cost central heating pump, it is unnecessary to use the large and expensive 28mm copper pipes. 22mm or even 15mm would work, and one could even use push fit piping if the plumbing is challenging. Also, as the pressure and temperatures are small, one could almost consider using plastic Hosing for most of the curved or difficult sections, with interface to copper where meeting the flowmeters and panels etc. and care taken to remove airlocks. This would reduce labour cost enormously.
Condensation is not the issue I thought it would be, as the operating temperatures are higher than the heatpump uses when working only to the ground. Condensation occurs, but the pipes are not dripping wet... just lightly spotted with wet. So thinner insulation would do on the flow pipes. On the return, some insulation is essential to reduce system losses (i.e it getting cold from the low loft temperature) but as the distance travelled is small (and so is delta-T), it can be thinner than 19mm.