20 Oct 2011: Naming games
I have been trying to think of a word for this phenomenon, and the word 'Catalytic' keeps coming to mind. In a sense this is where THREE plus ONE equals not four but SIX because the added ingredient is more than an arithmetical addition. But in Chemistry, strictly speaking, the catalyst is not part of the reaction, it is 'interfering' beneficially. So, catalyst is not the right word.
Twin boreholes with a shared warm zone. If the daytime
heat has been put down, the area around the pipes is
temporarily warmer than the greater mass around.
However a better analogy is 'Turbo' - in which momentum accumulated just prior to it being needed is then harnessed to add extra performance - as in turbocharged car engines. There, a turbine spinning in proportion to engine speed can suddenly be diverted to supplying air at a faster rate to the engine if you put your foot down while overtaking. The KERS system in Formula One cars stored rotational momentum of braking, shortly before granting that power to the car as it accelerates out of the corner.
At the equinox time, the heat delivered on a bright sunny day is stored immediately around the borehole pipe and it is warmer than the mass around it because of the warm daytime. So for the first part of the evening heating, the GSHP does not need to reach out to the larger mass around, it can simply grab that day's heat back first.
In winter, the heat falling on the sunbox on a sunny cold day is immediately useful to the GSHP and reduces its workload in clawing heat from down below.