In a monobloc, the entire refrigerant circuit stays in the outdoor unit: only two heating-water pipes run into the house. The result: no refrigerant handling on site, simpler and faster fitting, and no bulky indoor module to find space for. The direct solution for renovation.
The benchmarks that matter for a monobloc air-to-water heat pump fitted by our teams in Belgium. Concrete figures, no marketing.
For every 1 kWh of electricity used, the pump delivers more than 4 kWh of heat on average across the season. The SCOP drops if the flow temperature rises: aim for a low-temperature circuit (underfloor heating or oversized radiators).
Unlike the split, no refrigerant runs into the house: only heating water flows back and forth. The sealed refrigerant circuit stays confined to the outdoor unit, charged at the factory.
Since water circulates outside, the outdoor circuit must be protected from frost with antifreeze (glycol) or an electric resistance. A key design point under the Belgian climate — we size it as a matter of course.
Enough for well-sized existing radiators and hot water production. Efficiency stays better at low temperature: the ideal remains underfloor heating at 30–35 °C.
No wall-mounted hydraulic module indoors: the bulk sits in the outdoor unit. We only connect the water flow and return to the existing circuit and, where applicable, a hot water tank.
Depending on output, the monobloc connects in 230 V single-phase or 400 V three-phase. For Belgian suburban renovation, single-phase is enough in most cases — checked during the survey.
* Indicative values for a standard-range monobloc at low temperature. The real SCOP depends on the heating circuit, the emitter and the sizing — specified during the survey.
No configuration is perfect for every project. Here, honestly, is where the monobloc excels and where the split takes the lead.
It comes into its own whenever you want a direct fit, with no refrigeration complications and no space lost indoors. A few cases where it shines:
To replace a boiler without a major indoor job: we keep the existing water circuit and connect the outdoor unit. Quick start-up.
No wall-mounted hydraulic module to fit: the monobloc is perfect for homes where every square metre indoors counts.
Paired with underfloor heating or oversized radiators, it delivers its best SCOP and the gentlest bill.
If the unit has to sit at a distance or you are worried about frost, the split air-to-water range keeps the water safely indoors. And to secure deep-cold spells, the hybrid heat pump keeps a boiler on standby.
The owner of an 80s house wanted to drop oil without transforming the laundry room. We installed a monobloc air-to-water pump connected to the existing radiator circuit, with a glycol-protected loop: the job was wrapped up in a day, with no refrigeration engineer and no indoor module to fit.
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. »
The monobloc wins on fitting simplicity and the absence of an indoor module. Compare it point by point with the classic air-to-water range and the hybrid, then open the solution that suits you.
| Critère | Air-to-water monoblocVous êtes ici | Air-to-water heat pump (range)Voir la gamme → | Hybrid heat pumpVoir la gamme → |
|---|---|---|---|
| Link to the house | Water only | Refrigerant (split) | Water + gas/oil |
| Fitting simplicity | The simplest | Refrigeration engineer needed | More complex |
| Indoor module | None | Hydraulic module | Module + boiler |
| Frost risk | To protect (glycol) | Water safe indoors | Water safe indoors |
| Unit-to-house distance | To keep short | More flexible | More flexible |
| Deep cold | Good at low temp. | Good at low temp. | Boiler takes over |
| Ideal for | Simple renovation, little space | Free placement | Older home, harsh winters |
An overview of air-to-water, including the split where the refrigerant reaches an indoor module. More flexibility on placement.
See the air-to-water range →The heat pump for most of the year, a boiler taking over in deep cold. Maximum security in older homes.
Discover the hybrid →The ideal low-temperature emitter for a monobloc: at 30–35 °C flow, it delivers its best SCOP.
See underfloor heating →Air-to-air, air-to-water, geothermal, hybrid: understand the families and pick the technology suited to your home.
Compare the types →Regional grants, low-rate loan and 6% VAT: the share of the budget covered depending on your region and income.
See the grants →An overview of our heat pump solutions in Belgium: technologies, efficiencies, fitting and grants on one page.
Back to the heat pump guide →The price depends on output, the emitter in place and the frost protection. The monobloc’s simplified fitting often lightens the labour bill. Here are benchmarks for installed kit.
See the detailed heat pump price list →* Indicative ranges for an installed monobloc, excluding specific configurations. Costed estimate during your free quote.
In a monobloc, the entire refrigerant circuit stays in the outdoor unit: only two heating-water pipes enter the house. In a split, the refrigerant runs to an indoor module where the exchange takes place. The monobloc therefore avoids any refrigerant link on site.
No. Since no refrigerant runs into the house, the link to the home is purely hydraulic. A qualified heating installer is enough, which simplifies and speeds up the job — often wrapped up in a day.
This is the monobloc’s main point of attention in Belgium. Since water flows outside, we protect the circuit with antifreeze (glycol) or a frost-protection resistance, and anticipate any prolonged power cut in winter. We size this protection as a matter of course.
No, and that is one of its big advantages: no wall-mounted hydraulic module to fit inside. We only connect the water flow and return to the existing circuit and, if needed, a hot water tank. Ideal when space is tight indoors.
As close as possible to the water entry point. The longer the hydraulic link, the more heat losses there are and the lower the efficiency, even with well-insulated pipes. A close location is therefore recommended — we confirm the spot during the survey.
Grants depend on performance (SCOP), not on the type of link. A high-performance monobloc qualifies, depending on your region and income, for a heat pump grant, 6% VAT in renovation and sometimes a low-rate loan. We handle the paperwork for you.
Free home survey, grants calculated, a single point of contact. Describe your project in under a minute.