Summer heating updated

There was some concern that the boreholes would cool over the years as the conduction-based re-heating times are very long (centuries).  However, checking ground temperature this August by switching the ground loop pump to continuous on (menu 5.11) whilst the heat pump is not in operation shows a ground temperature stabilising at 10C after 36 hours, much as originally (see the diagram above).  This is presumably due to groundwater movements increasing the effective rate of re-heating.  At all events it looks as if no summer re-heating is necessary.