Air-to-water heat pumps dominate the Dutch market — rightly so for most terraced and corner homes. But once you look at large detached villas, poorly insulated period properties or new-build with a garden, another type of heat pump deserves attention that many installers under-discuss: the Daikin Altherma 3 GEO.
This review is based on the official Daikin NL 2026 catalog (pages 142–147), supplemented by hands-on experience from 12+ GEO installations we supervised in 2024-2026. Every spec below is sourced.
✓Key takeaways
- ●COP 4.51–4.7 @B0/W35 — constant year-round
- ●No outdoor unit: 0 dB at the property line
- ●39–41 dB(A) Lw indoors — whisper quiet
- ●50+ year collector, 20-25 year heat pump
1. The technical principle — why GEO stays at COP 4.5+
The Altherma 3 GEO draws heat from a closed brine loop at 80–100 m depth in the ground (Daikin catalog p.143). At that depth Dutch soil sits at 10–12 °C all year — far higher than winter air (-5 to 5 °C). The temperature lift the heat pump must bridge is structurally smaller.
In numbers: a COP of 4.51 (size 06) up to 4.7 (size 10) at the B0/W35 test point. For comparison: an Altherma 4 H air-to-water pump reaches SCOP 5.1+ in a temperate climate, but that SCOP is a season average — on cold days the actual COP drops to 2.5–3.5. With GEO the COP stays constant.
2. Who is this the right choice for?
We see three clear buyer profiles where GEO is superior to air-to-water:
A. Detached villas (180+ m²)
With high peak heat demand (>10 kW), an air-to-water pump runs into efficiency limits on cold winter days. The GEO size 10 (EGSAH10D9W / EGSAX10D9W) delivers up to 9.55 kW @B0/W35 (catalog p.146) and holds that all season.
B. Poorly insulated large homes
For homes where deep retrofit insulation is not financially feasible (e.g. listed status, masonry façades), GEO delivers the highest seasonal-efficiency class: ηs 195–200 % at 35 °C and ηs 141–154 % at 55 °C — A+++ across the range (catalog p.146).
C. New-build with deep-drilling possibility
For new construction the borehole is easy to integrate during the build phase. The Altherma 3 GEO can also be combined with heat-pump convectors and underfloor heating for a complete electric comfort system (catalog p.143).
3. Installation reality: drilling, permits, lead time
Now the honest, non-easy part. A GEO installation is not a weekend job.
The drilling itself
A SIKB BRL-2100 certified driller sinks 1 or 2 vertical boreholes of 80–100 m. The drilling rig needs access (minimum 2.5 m wide passage) and a working area of ~10×10 m. One 100 m hole takes a full day. The polyethylene U-pipe is then inserted and the borehole backfilled with thermally conductive grout.
Permits and regulations
Vertical ground heat exchangers fall under the Dutch Soil Protection Act (Wbb). In water-extraction areas and groundwater protection zones drilling is often forbidden or permit-bound — your province publishes these zones via PDOK. Outside those zones a notification (BUS-melding) usually suffices.
Lead time
From order to working installation expect 8–14 weeks: 2-4 weeks for permit/notification, 4-6 weeks Daikin indoor unit lead time, 1 week drilling, 1 week installation and commissioning. Don't plan this mid-October if you need heat in November.
4. 25-year TCO: where the extra investment pays back
An Altherma 3 GEO including borehole costs an indicative €15,000–22,000 (excl. VAT and ISDE). An Altherma 4 H air-to-water pump comes in at €8,000–12,000. That gap of €7,000–10,000 is the hurdle a buyer must clear.
But run a 25-year calculation for a household spending €2,500/year on heating. GEO delivers structurally 25–30 % lower running cost thanks to the higher seasonal COP. That is €625–750 saving per year — €15,000–18,750 over 25 years. The extra investment pays back in 9–12 years; after that it is pure profit.
And: the borehole lasts 50+ years. When the heat pump is replaced after 25 years the ground loop stays intact and only the indoor unit is swapped. With air-to-water you depreciate the entire outdoor unit again in 25 years.
5. Sound: 0 dB at the property line
The biggest practical win of GEO: nothing sits outside. No fan, no compressor in the garden, no debate about minimum metres to the property line.
The indoor unit produces 39–41 dB(A) sound power (Lw) and 27–29 dB(A) sound pressure at 1 m (catalog p.146). In a closed plant room it is inaudible from the adjacent living space.
Especially relevant for: dense villa neighbourhoods, noise-sensitive HOAs, limited outdoor space. Between 2024 and 2026 we ran several installations where the neighbour had already filed a complaint against an air-to-water unit — GEO solved the conflict by definition.
6. What others won't tell you
Three aspects consistently missing from commercial brochures:
Lead time beats price
Certified SIKB BRL-2100 drillers are scarce in the Netherlands. In the high season (Sept-Nov) waits of 6-8 weeks are normal. We expect 2026 to extend further as the Climate Agreement bites. Plan early.
Brine-loop and glycol maintenance
The brine loop contains a glycol-water mix (anti-freeze). Daikin supplies the KGSFILL2 fill kit (catalog p.147). Glycol must be checked every 5-7 years for pH and concentration — typically part of the annual maintenance contract. Not expensive (€80-120 per check) but a difference versus air-to-water.
Anti-freeze operation
The glycol-side operating range is -10~30 °C (catalog p.146). With correct fill, freezing in Dutch soil is never an issue, but with shallow horizontal collectors (alternative concept) surface frost can affect the COP. Vertical drilling (Daikin's recommendation) does not have this problem.
7. Pros & cons — honestly weighted
Pros
- Constant COP 4.51–4.7 @B0/W35 — weather-independent
- No outdoor unit — 0 dB at property line
- 50+ year borehole life
- A+++ at both 35 °C and 55 °C
- Integrated 180 L stainless DHW tank
- Standard Onecta + Madoka compatible
- Works with existing low-temperature radiators up to 65 °C
Cons / things to watch
- €7,000–10,000 higher CAPEX than air-to-water
- Borehole needs garden + rig access
- Soil-protection notification or permit needed
- Lead time 8–14 weeks
- Glycol check every 5–7 years
- R-32 refrigerant (GWP 675) — no R-290 here
- 222 kg indoor unit — floor must support it
8. Conclusion
The Daikin Altherma 3 GEO is not a mass product. For an average terraced home an Altherma 4 H Small with R-290 is smarter and cheaper. But in the niches GEO is built for — detached villas, poorly insulated large homes, new-build with a garden — over 25 years it is the most economical and most comfortable choice.
Our rating: 4.6 / 5. One point off for the R-32 refrigerant (worth re-evaluating in 5 years as F-gas regulation tightens) and the high entry cost.
FAQ
Does a Daikin Altherma 3 GEO need an outdoor unit?
No. Unlike air-to-water heat pumps the entire heat pump sits indoors — typically in a utility room, basement or boiler cupboard. Outside, only the ground collector is visible (sealed manhole covers at ground level). The indoor unit weighs 222 kg and measures 1,891 × 597 × 666 mm (catalog p.146).
How deep and how often do you drill?
Daikin specifies a vertical borehole of 80–100 m for a constant inlet temperature (catalog p.143). Larger homes typically need 2 boreholes with a minimum 6 m spacing. A SIKB BRL-2100 certified driller carries this out in the Netherlands.
What COP does the GEO deliver versus an air-to-water heat pump?
COP @B0/W35 for the Altherma 3 GEO is 4,51 (size 06) up to 4,7 (size 10) — catalog p.146. More importantly: because the ground stays at 10–12 °C all year, the COP stays constant. Air-to-water heat pumps lose efficiency in frost (COP drops to 2.5–3.5 at -10 °C ambient).
What does a Daikin Altherma 3 GEO cost including borehole?
Indicative total €15,000–22,000 including vertical borehole (€60–80/m), indoor unit and standard installation. Excl. VAT and Dutch ISDE subsidy. The 6 kW size (EGSA(H/X)06D9W) is cheaper than the 10 kW (EGSA(H/X)10D9W). Site survey required for an exact quote.
Am I allowed to drill a vertical borehole on my property?
In the Netherlands vertical ground heat exchangers fall under the Soil Protection Act (Wet bodembescherming). In water-extraction areas and groundwater protection zones drilling is often forbidden or permit-bound — your province publishes these zones via PDOK. Outside those zones a notification (BUS-melding) to the municipality or environmental agency usually suffices.
How long do the borehole and the heat pump last?
Ground collectors typically last 50+ years — when the heat pump is replaced after 20–25 years the borehole stays intact and only the indoor unit is swapped. This significantly lowers life-cycle cost compared with air-to-water systems.
Does a GEO work with my existing radiators?
Yes. The Altherma 3 GEO supplies up to 65 °C flow temperature (catalog p.146 — heating water-side range 5~65). That makes it suitable for low-temperature radiators, underfloor heating and heat-pump convectors. For older radiators designed for 80 °C, an output check per room is recommended.
How much Dutch ISDE subsidy do I get on an Altherma 3 GEO?
Ground-source heat pumps attract a higher 2026 ISDE amount than air-to-water — typically €3,500–5,500 depending on capacity and SCOP. We arrange the ISDE application together with the installer.
Sources & references:
- Daikin Altherma 3 GEO — 2026 NL product catalog, pages 142–147 (technical specs EGSA(H/X)06D9W and EGSA(H/X)10D9W).
- Daikin Service & After-Sales — Stand By Me Certified Partner Programme, 2026 NL catalog page 376.
- SIKB BRL-2100 / BRL-11000 — protocol for mechanical drilling and ground-energy system design (NL 2025/2026).
- Dutch Soil Protection Act (Wbb) — notification and permit duty for vertical ground heat exchangers per province.
- Field experience: 4 GEO SKUs in our spec database, 12+ supervised installations 2024-2026.