subsoil heat exchanger

[MahBumble]

I'm looking to include a subsoil heat exchanger into my HVAC system. Any suggestions would be appreciated on how to best emulate it.

I'm guessing I'll have to set a heater which heats air a little during cooler periods, and manually subtract the energy required to do so from my final heating energy.

Cheers, Tom

[MahBumble]

Solved - Have since found the discussions on modelling earthtubes, was just using the wrong terminology.