Interseasonal Thermal Storage

This is based on ideas from Drakes Landing Solar Community .

Before starting to build I drilled five200mm 9m deep boreholes on the site, two of these are for my interseasonal thermal storage. These are approximately central under each half of the house. On digging out the basement we were careful not to damage the pipes loaded into and grouted and managed to carefully re route them to in line with the central basement wall. These pipes now transpoer warm and hot water down under the house to a depth of 6.5m below the basement floor.

The heat will be from the deliberate excess of solar thermal capture during the warmer months. I will probably have to insulate the basement floor to stop it getting to warm down there! (Actually did not need to all fine in 2017 as the store maximum is still cooler than the basement)

I have three loops of pipe one full depth in each bore hole and one half depth in one bore only.

None of the holes hit any water! Two of the others are for drainage and one for a poor mans gshp or “earth tube” set up to pre-warm incoming ventilation air. (Not yet in use)

The basement floor has only 25mm of EPS insulation at present under a floating floor.

In April 09 — solar thermal panels were fitted and connected up to ground loops. The thermal store tank gets to 85C and the ground loops dump all the heat by the next day but only just. I am scared that my ground loops do not have enough capacity to dump all the solar heat down there. I can turn up the temp on my thermal mixing valve 42 at present, and speed up the pump too, and once we live there we will use some heat for hot water. The good thing is the water goes down hot and the return is lukewarm. When the ground loop got an air lock from degassing the solar panels it all boiled, this was a one off glitch.  The antifreeze in the system is electronic, simply switching in the pump, wasting a little solar gained heat to stop the pipes and panels freezing. In 2017 all working nice, heat starts being collected for the interseasonal store during March.