Balance suggestion for Geothermal heater

[Aberro]

Currently, there's not much sense to build one, as it's barely more efficient than electric boilers with geothermal generator. There's some savings in materials also. But in total, generator with electric boilers is more superior option, simply because of it's flexibility. It seems that geothermal heater should be more balanced. Realistically, generators energy conversion efficiency is at mere 10-15% (https://www.geothermal-energy.org/pdf/IGAstandard/NZGW/2012/46654final00097.pdf). And using that energy for heating in presence of available geothermal energy is generally a bad option, especially for central heating.
Probably, making a geothermal heater producing realistic 30000J would be an overkill, but something like 6000J should balance it against electric boilers.