Assuming the land is approved for geothermal boring, has anyone actually gone through the process for an existing house? Would you mind sharing the overall costs, and how destructive it was? I’m not even sure this is possible if you need to bore many metres into the ground in a confined basement space.
Not myself but a number of neighbors usually in the garden, one got permission to dig up the pavement and ran the hoses underground into his house.
Never made a retrofit, but I support the people doing the calculations to dimension the underground part of the system and getting permits approved.
So, near impossible to drill below your house. It makes more economical sense to drill 1 or 2 boreholes in the garden. If there is no groundwater below your house, it will probably be a single borehole around 100m deep. Bit more, bit less depending on how much energy is required. If there is groundwater, there’s a extraction borehole and and reinjection borehole. They only need to be as deep to reach groundwater.
The permit from authorities is mainly focused at the impact your installation may have on the groundwater environment. The concern is that a lot of people may be competing for the same resources and new installations should not make other previous installations underperform.
Back to your question. No drilling below your house. The only work required is to install underfloor heating. Why? Underfloor heating works with fluid temperatures compared to other house heating systems. Geothermal systems deliver also lower(ish) heated water temps. So, geothermal systems and underfloor heating are a perfect match.
About things broken in the process, there shouldn’t be many. There’s a truck with a miniature drilling rig on top of it. Vibrations should be minimal. There’s noise, but following adequate operational methods law can be followed.
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We had it done about 8 years ago. Total cost was about 80k but we got a 10% rebate from Vaud. Two 130m holes drilled in driveway and pipes laid underground into basement. Tiday there is nothing to see. We have underfloor heating which the heat pump, replacing electric boiler, connected to.
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Thank you very much for the information. So we’d have to drill in the garden somehow, and pull the pipes to the house. The house already has underfloor heating, so it should be a swap of the oil header → heat pump.
Thanks, that is enough information to know “it is possible”. Now, to find a company, get a quote, figure out if its actually that possible or not (the property is not suited with trivial vehicle access, there would need to be some driving over neighbouring property). 80K is also a bit steep… but we’ll see. As far as I can tell from the Zurich maps (GIS-Browser) there is no risk of groundwater, and there is a house a plot over with a 90m hole (or two if I’m reading it correctly) for 10kW of heat extraction.
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We changed a dirty oil heating system to an geothermal and heat pump about 10 years ago. We needed a geological expert to be present for the hole boring by Terracalor. Everything was coordinated by the heating company with experience of such systems. We also had solar panels installed around the same time and the cost of just the electricity plummeted to 50% of our previous electricity and oil bills. Our house was built in 1975 with standard radiators, but because the HP has a 60oC flow temperature that’s really not a problem. The current models are even better. Just one comment, make sure the heating installers calculate the geothermal depth correctly so you get the correct kW system.
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Indeed, that map is the regulation of land use for heat extraction 
I assume your house is in a zone where Erdwärmesonden (borehole heat exchangers) are allowed. If that’s the case, it’s only 1 borehole. Hopefully the drilling rig can access without having to break anything. The drilling rig is about 2.1-2.2 meters wide. The space needed for the work can be inferred from these photos:
https://www.erdenergie.ch/de/maschinenpark/uebersicht-maschinenpark
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Thank you. That helps. There is “easy” access to our garden, but it via private property (its just an empty field). I’ll have to find out who we could contact eventually for approval to roll over their ground.
Does anyone have any recommendations for companies to reach out to for work in KT Zürich? I’ve reached out to a few, but if there are recommendations it is always handy.