Air-to-air, air-to-water, geothermal, hybrid: they all capture free energy from the environment, but their use, efficiency and cost differ. This guide compares the four families to point you in the right direction before the quote.
They all capture free energy, but their use differs. Here is what each type brings in practice.
Captures heat from the air and delivers it through splits. Heats and cools, without a water circuit or hot water. Ideal as a supplement or per room.
Feeds radiators or underfloor heating and produces hot water. The go-to replacement for an oil or gas boiler.
Draws the stable heat of the ground via collectors or a borehole. Record efficiency all year round, a heavier investment.
Pairs a heat pump with your boiler: the heat pump handles everyday needs, the boiler takes over in severe cold.
They all deliver several kWh of heat per kWh consumed. Geothermal leads, with air-to-air and air-to-water following closely depending on the emitter.
Reduced VAT at 6% in renovation and 2026 regional grants that vary by type — air-to-water and geothermal are the best supported.
* Indicative benchmarks. The optimal type and sizing depend on your home and its insulation — determined during the technical survey.
The right type depends on your home, your emitters and your budget. Here is how to navigate based on your situation.
The home guides the choice as much as the budget. Three common situations:
With radiators and a boiler to replace, air-to-water — possibly hybrid — is most often the right comfort/grants compromise.
When the water circuit is complicated to redo, an air-to-air multi-split heats and cools without major works.
In a well-insulated new build, geothermal or air-to-water on underfloor heating offer the best efficiency over time.
Our technicians decide during the survey based on your insulation, your emitters and your needs. Start with the air-to-water heat pump if you are replacing a boiler, or the air-to-air heat pump for a reversible supplement.
One family, two properties: a town house to renovate and a studio to equip. During the survey, we proposed air-to-water on validated radiators for the house, and a reversible air-to-air mono-split for the studio. Each home received the most cost-effective type for its setup.
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The table to see at a glance what each type brings. The right choice depends on your home, its insulation and your budget.
| Critère | Air-to-waterVoir la gamme → | Air-to-airVoir la gamme → | GeothermalVoir la gamme → | HybridVoir la gamme → |
|---|---|---|---|---|
| Central heating | Yes | No (air) | Yes | Yes |
| Domestic hot water | Yes | No | Yes | Yes |
| Cooling | Depends on model | Yes | Passive | Depends on model |
| Efficiency (SCOP) | 3.5–4.8 | 3.5–4.5 | 4.5–5.5 | 3.5–4.5 |
| Investment | €€€ | € | €€€€ | €€€ |
| Best for | Replacing a boiler | Supplement, cooling | New build, long term | Transition |
Central heating + hot water, the go-to replacement for a boiler. Strongly grant-supported in 2026.
All about air-to-water →Warm in winter, cool in summer, installed in a single day with no water circuit. Ideal as a supplement or per room.
All about air-to-air →The stable heat of the ground for the best efficiency all year round. A heavier investment, built to last.
Discover geothermal →Heat pump + boiler as backup: the security of severe cold and a gradual switch to renewables.
See hybrid →Installed price ranges by type and grant amounts depending on your region and income.
See the prices →An overview of our heat pump solutions in Belgium: sizing, grants and installation.
Back to the heat pump guide →The budget varies widely by type. Here are some benchmarks for installed equipment, from the most affordable to the highest performing.
See the detail of prices & grants →* Indicative ranges for installed equipment, grants not deducted. A costed estimate is provided with your free quote.
In pure efficiency terms, geothermal leads thanks to the stable temperature of the ground. But "best" depends on the home: for a house with central heating, air-to-water offers the best performance/price ratio; for a single room, air-to-air is unbeatable for simplicity.
Air-to-water, in the vast majority of cases: it connects to the existing circuit (radiators or underfloor) and produces hot water. If you want to keep the boiler as backup for severe cold, the hybrid version is a reassuring transition.
Often the air-to-air multi-split: no water circuit to redo, fast installation and cooling as a bonus. In a shared building, the location of the outdoor unit and the building rules should be checked beforehand.
The higher the efficiency (SCOP), the lower the bill. Geothermal consumes the least, followed by air-to-water on underfloor heating. Air-to-air remains very economical against direct electric heating. The insulation of the home matters as much as the type chosen.
No. Air-to-air only heats the indoor air. Air-to-water, geothermal and hybrid can produce domestic hot water via a tank. If hot water is part of your needs, we steer you towards those types.
Air-to-water and geothermal are the best supported by regional grants, because they provide complete central heating. The 6% VAT applies to all types in renovation (homes over ten years old). We calculate your eligibility before the quote.
Free technical survey, type chosen during the survey, grants calculated. Describe your project in under a minute.