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Hybrid heat pump: the heat pump that keeps your boiler as a safety net
The hybrid heat pump pairs an air-to-water heat pump with your existing gas or oil boiler. A smart controller automatically picks the most efficient source: the heat pump handles everyday needs (75–85% of heating hours), the boiler takes over in severe cold. Ideal for cutting carbon without changing everything.
- −50–70%
- gas or oil
- 75–85%
- of the time on the heat pump
- Boiler
- backup in severe cold
What a hybrid heat pump is really worth
The principle: the heat pump heats while it is efficient, the boiler tops up when needed.
- Heat pump efficiency SCOP 3.5–4.5
The heat pump part reaches a seasonal efficiency comparable to a standard air-to-water unit. The controller optimises the switchover.
- Boiler backup Automatic
When the outdoor temperature drops below the bivalence point (~2–5 °C), the boiler takes over. The switchover is seamless.
- Fossil fuel reduction 50–70%
The heat pump covers 75 to 85% of heating hours. Oil or gas is only used in severe cold: fossil fuel consumption falls by 50 to 70%.
- Existing radiators Compatible
The hybrid heat pump works with your existing radiators. No need for underfloor heating or to replace the emitters.
- Installation Minimally invasive
The outdoor unit connects to the existing circuit via a controller. No structural work, no boiler replacement (it stays in place).
- Severe-cold security Boiler as backup
Even during prolonged severe cold, the boiler ensures comfort. No risk of undersizing the heat pump.
* Indicative values. The bivalence point and the heat pump/boiler split depend on the insulation and the emitters.
Pros & cons of hybrid
Hybrid is a transition, not an endpoint. Here is when it stands out and when a full heat pump is a better fit.
Where it shines
- Risk-free transitionKeeps the boiler as backup — no risk to comfort in severe cold.
- Radiator compatibilityWorks with existing emitters, even old ones.
- −50–70% fossil fuelA massive cut in gas or oil consumption from day one.
- Fast, minimally invasive installationConnection to the existing circuit, boiler kept in place.
What to keep in mind
- Still partly fossil-fuelledThe boiler keeps running in severe cold — no full decarbonisation.
- Two systems to maintainThe heat pump and the boiler each require periodic maintenance.
- A transitional solutionWhen the boiler reaches the end of its life, you will need to decide whether to replace it or go full heat pump.
- Sometimes lower grantsSome grants are higher for a complete replacement by a full heat pump.
Is hybrid right for you?
It stands out when you want to cut carbon without turning everything upside down. Three common situations:
-
Boiler still in good condition
Your boiler is less than 10 years old and works well. Hybrid adds a heat pump without removing it: a sensible transition.
-
Poorly or moderately insulated home
In a poorly insulated home, a full heat pump would be oversized. Hybrid adapts: the boiler compensates in severe cold.
-
Need for security and a transition
For anyone who wants to cut fossil fuel without risking comfort. The boiler is reassuring.
If your home is well insulated or if the boiler is at the end of its life, the air-to-water heat pump on its own is often more cost-effective and eligible for better grants. We compare the two options during the survey.


An 8-year-old gas boiler complemented by a hybrid heat pump
The gas boiler was recent and in good condition. Rather than removing it, we connected an air-to-water heat pump in hybrid mode. The result: the heat pump handles 80% of the heating, the boiler only runs 30 days a winter. Gas consumption divided by three.
- ÷3gas consumed
- 80%of the time on the heat pump
- 30 daysof boiler use/winter
They chose wendows
5.0/5 · 3verified reviews
« 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. »
Hybrid, full air-to-water or keep the boiler?
Three strategies for your heating. Hybrid is the compromise.
| Critère | Hybrid heat pumpVous êtes ici | Full air-to-waterVoir la gamme → | Boiler aloneVoir la gamme → |
|---|---|---|---|
| Fossil fuel reduction | 50–70% | 100% | 0% |
| Severe-cold security | Boiler takes over | Electric backup | Boiler |
| Investment | Mid-range | Higher | €0 (existing) |
| Existing radiators | Compatible | To be checked | Compatible |
| Grants | Supported | The highest | None |
| Maintenance | Heat pump + boiler | Heat pump alone | Boiler alone |
| Best for | Transition, recent boiler | Full decarbonisation | Status quo (not recommended) |
- vs hybrid
Air-to-water heat pump
The complete replacement of the boiler. Better grants, full decarbonisation.
Compare with full air-to-water → - as a complement
Air-to-air heat pump
As a supplement for a specific room or summer cooling.
See air-to-air → - the best performer
Geothermal
The best efficiency, if the land and budget allow.
Discover geothermal → - ideal emitter
Underfloor heating
Hybrid also works with underfloor heating for optimal comfort.
See underfloor heating → - budget
Price & grants
Installed hybrid price ranges and 2026 regional grants.
See the prices → - ↑ category
All heat pumps
An overview of our heat pump solutions in Belgium.
Back to the heat pump guide →
How much does a hybrid heat pump cost?
The cost is lower than a full air-to-water unit because the boiler and the emitters stay in place.
See heat pump prices & grants in detail →* Indicative ranges for installed equipment. The fossil-fuel saving depends on the insulation and the bivalence point.
- Hybrid heat pump (connection) €7,000–12,000heat pump + controller, installed
- Without boiler replacement Includedexisting boiler kept
- Wallonia grant up to €4,000depending on income and region
- Reduced VAT 6%in renovation (home > 10 years)
Your questions about hybrid
Does the boiler stay in place? +
Yes, that is the whole point. The heat pump connects to the existing circuit via a smart controller. The boiler stays your safety net in severe cold.
How much gas or oil do you save? +
Generally a 50 to 70% reduction. The heat pump covers 75 to 85% of heating hours. Fossil fuel is only used during periods of prolonged severe cold.
Is my boiler compatible? +
Most recent gas or oil boilers are compatible. We check during the survey: the hybrid controller adapts to most brands.
And when the boiler reaches the end of its life? +
You will have a choice: replace it with a new one to stay hybrid, or switch to a full air-to-water heat pump. By then, your home may be better insulated and the full heat pump will be enough.
Is hybrid eligible for grants? +
Yes. Adding a heat pump qualifies for regional grants (Wallonia, Brussels) and the 6% VAT in renovation. The amounts are sometimes lower than for a complete replacement.
Is hybrid suitable for a poorly insulated house? +
That is precisely where it excels. In a poorly insulated home, a full heat pump would be oversized and less efficient. Hybrid adapts: the heat pump handles everyday needs, the boiler covers the peaks.
Get your free hybrid heat pump quote within 48h
Free technical survey, boiler compatibility checked, grants calculated. Describe your project in under a minute.
- Free and with no obligation
- Boiler compatibility checked
- Installed by our certified technicians