Groundwater stays at roughly 10 °C all year round. That makes it the most stable and rewarding heat source available. The result: COP up to 6.4 – every kilowatt-hour of electricity yields over six kilowatt-hours of heat.
Why water
- Highest efficiency of all heat pump types
- Lowest running costs – stable source temperature = minimal compressor draw
- Quiet operation – no outdoor fan unit
- Weather-independent – performs the same at -20 °C or +35 °C outside
What you need
- Source well with sufficient yield
- Absorption well for returning the cooled water back
- Hydrogeological survey – confirms water quality and yield
- Extraction permit for groundwater from the relevant authority
Water quality is decisive – iron, manganese and other mineral levels must stay within limits. A hydrogeologist will verify this.
HOTJET specialty: direct water connection without an intermediate exchanger
HOTJET is one of the few manufacturers that allow direct connection of well water to the heat pump without an intermediate heat exchanger. This means higher efficiency and a simpler system.
- Tubular/coaxial heat exchanger – withstands freezing and handles impurities better
- Inverter-controlled well pump – fully managed by the regulation system
- Fully inverter-driven system – compressor, well pump and circulation pump all modulate output continuously
Heat Pump Explorer
Air–Water 7 · 10 · 15 kW Proven classic
HOTJET ZETXe
Reliable alternative to ZETXp
Same platform as ZETXp, proven by thousands of installations. Inverter, 3 circuits as standard.
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Air–Water 7 · 10 kW The coming standard
R290
HOTJET ZETXp
Natural refrigerant R290, GWP 3
Natural R290 propane refrigerant with minimal climate impact. Ready for EU regulations beyond 2027.
Learn more → Air–Water 15 · 20 kW Higher output
R290
HOTJET 15-20 ZETXp
R290 propane for larger buildings
Three-phase 400V power, larger housing. For family homes, apartments and commercial buildings with 10–30 kW heat loss.
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Air–Water 10 · 15 kW All indoors
HOTJET ZETXi
Complete indoor installation
No outdoor unit, no noise for neighbours. Ideal for terraced houses and dense residential areas.
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Ground–Water 7 · 10 · 15 kW Ground–Water
HOTJET Wx
Most efficient, longest lifespan
Geothermal source = stable output all year round. SCOP over 5, lifespan 25+ years.
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Water–Water 7 · 10 · 15 kW Water–Water
HOTJET Wx Coax
No intermediate exchanger, direct output
Coaxial heat exchanger directly in the borehole. Fewer components, higher efficiency.
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Air–Water 5 kW Compact
HOTJET Mini
Smallest air-source heat pump
Minimal dimensions, maximum output per m². Passive houses, low-energy buildings.
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Air–Water 20 · 25 · 35 · 45 · 55 kW Indestructible
HOTJET ONE2
Simple. Robust. Reliable.
Minimal component count, maximum serviceability. Engineered to run trouble-free for years.
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Accessories 70 kW Accessory
HOTJET FW
Flow-through DHW module
Hygienic hot water without a tank. Plate heat exchanger 70 kW, flow rate 25 l/min.
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Accessories Accessory
HOTJET HMD
Hydromodule – wall-mounted hydraulic unit
Complete solution in one cabinet: Siemens control, 7.5 kW electric boiler, circulation pump, 3-way valve and webserver.
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Accessories Accessory
HOTJET RZ
Switchboard – control & protection
Electrical cabinet with Siemens control. Manages heating circuits, boiler, pumps and valves.
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Hybrid 10 + 25 kW Hybrid
HOTJET H25/10
Pellet boiler + heat pump in one
Hybrid system: 25 kW pellet boiler + 10 kW heat pump. Siemens controller picks the cheapest source.
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