A thermodynamic water heater is a mini heat pump dedicated to domestic hot water. It draws warmth from the surrounding air (garage, utility room, cellar) to heat a 200 to 300-litre tank — using three times less electricity than a conventional electric boiler. Ideal as a replacement or alongside an air-to-air heat pump.
The figures that matter when choosing between a conventional boiler and a thermodynamic one.
For every 1 kWh of electricity, the thermodynamic water heater delivers 2.5 to 3.5 kWh of heat. A conventional electric boiler: 1 for 1.
200 L for 2–3 people, 300 L for 4 or more. Water is heated to 55–60 °C and stored. The built-in heat pump reheats it gradually.
The water heater draws warmth from the air in the room where it sits. Some models pull in outdoor air through a duct.
The unit operates when the surrounding air is between 5 and 35 °C. An unheated garage in Belgium suits it for most of the year.
Noisier than a conventional boiler (fan + compressor). Best installed in a technical room, not a living space.
A backup electric element takes over if the ambient air is too cold or demand is exceptionally high.
* Indicative values. The COP depends on the ambient air temperature and the tank temperature setting.
A thermodynamic water heater is a clear upgrade over an electric boiler, but it comes with constraints.
It excels in a few specific setups:
The most cost-effective case: moving from a 1-for-1 boiler to a COP of 3. Your hot water bill drops immediately.
An air-to-air heat pump doesn’t produce hot water. The thermodynamic unit completes the setup: air-to-air heating + thermodynamic hot water.
Run during solar production hours, the thermodynamic heater warms water with your surplus: virtually free hot water.
If you need both heating AND hot water, an air-to-water heat pump does both in a single system. A thermodynamic heater only makes sense for hot water alone.
A 150 L electric boiler that used 2,200 kWh/year for hot water. Replaced by a 200 L thermodynamic unit installed in the utility room: the electricity used for hot water fell to 700 kWh/year. An immediate saving of around €350/year.
5.0/5 · 3verified reviews
« Châssis, panneaux et pompe à chaleur en une seule fois : on a eu un seul devis, un seul planning et zéro paperasse pour les primes. Le résultat est impeccable et notre facture d'énergie a chuté. On ne pensait pas que ce serait aussi simple. »
« Passage du mazout à une pompe à chaleur air-eau. Chantier propre, anciens radiateurs conservés. La maison est mieux chauffée pour bien moins cher. »
« PAC air-air réversible installée avant l'été. Confort été comme hiver, et le SAV répond vite. Très satisfait du suivi. »
Three ways to produce hot water. Here’s how they stack up.
| Critère | ThermodynamicVous êtes ici | Electric boilerVoir la gamme → | Air-to-water + tankVoir la gamme → |
|---|---|---|---|
| COP | 2.5–3.5 | 1 (element) | 3.5–4.8 |
| Also does the heating | No | No | Yes |
| Price | €2,000–4,000 | €500–1,500 | €9,000–16,000 |
| Installation | Simple | Very simple | Hydraulic circuit |
| Noise | 40–50 dB | Silent | Outdoor unit |
| Solar pairing | Excellent | Possible | Excellent |
| Ideal for | Hot water only, boiler replacement | Tight budget | Full heating + hot water |
Heating + hot water in a single system. The go-to replacement for a boiler.
See air-to-water →Air-to-air heats and cools, but doesn’t produce hot water. The thermodynamic unit completes it.
See air-to-air →Paired with panels, the thermodynamic heater warms water with your surplus: virtually free.
See solar →Solar kit + thermodynamic heater: renewable electricity and hot water.
See the kits →Price ranges for an installed thermodynamic unit and regional grants.
See prices →An overview of our heat pump solutions in Belgium.
Back to the heat pump guide →The price depends on the tank capacity and the brand. Here are some benchmarks for installed equipment.
See full heat pump prices & grants →* Indicative ranges for installed equipment. Your actual saving depends on your hot water consumption.
More than a conventional boiler: 40 to 50 dB (fan + compressor). That’s why it’s installed in a garage, utility room or cellar — never in a living space or against a bedroom wall.
A ventilated room of at least 10–15 m³, between 5 and 35 °C. A standard garage or utility room works fine. The unit blows out cold air: the room cools slightly.
Yes. The thermodynamic heater runs on electricity and needs no gas. It replaces both an electric boiler and a gas-fired water heater equally well.
Compared with an electric boiler, the saving is 50 to 65% on hot water, or €200 to €400/year for a household. Paired with solar panels, the saving grows even further.
Yes, and it’s one of its best uses. By scheduling heating during solar production hours, hot water is produced with your surplus — virtually free.
200 L for 2–3 people, 300 L for 4 or more. The stored tank offsets the heat pump’s slower heating speed. We size it to your real consumption.
Free site survey, precise sizing, grants calculated. Describe your project in under a minute.