Energy & insulation
Heat pump or condensing boiler: which to choose in 2026?
Air-to-water heat pump or gas condensing boiler: installed prices, 21% VAT on the boiler since July 2025, rules by region and how insulation tips the choice.
By the Batizzy teamPublished Updated 6 min read
A new heating system ties a house down for fifteen or twenty years. In Belgium, the choice usually comes down to an air-to-water heat pump or a gas condensing boiler, and the comparison is not the one it was two years ago: gas boilers now carry 21% VAT, the regions are tightening the rules on fossil fuels, and the aid has changed shape. Here are the figures to decide, keeping in mind that the insulation of the house weighs more than everything else.
What has changed since 2025
On VAT, a gas or oil boiler installed during a renovation has been invoiced at 21% since 29 July 2025 for its specific part (boiler, flue, fuel supply, installation included). Radiators, underfloor heating and pipework stay at 6% if the invoice splits the two rates. A heat pump keeps the reduced rate in a home more than 10 years old.
On the rules, in Wallonia, oil boilers have been banned in new buildings since 1 January 2026, and installing or replacing one in an existing building will be banned from 1 January 2031. In Brussels, installing an oil boiler has been banned since 1 June 2025, and natural gas boilers are banned in fully new projects whose permit was applied for from 1 January 2025.
On aid, Wallonia stopped paying grants per job on 1 October 2026: Rénopack finances efficient, low-carbon heating (heat pump, biomass boiler) within a project that gains a PEB label. In Brussels, no Renolution grant is open for work invoiced in 2025 or 2026. In Flanders, Mijn VerbouwPremie covers heat pumps, with amounts that depend on the applicant's profile.
The air-to-water heat pump
It draws heat from the outside air and sends it into the central heating, through radiators or underfloor heating. With 1 kWh of electricity, it produces 3 to 4 kWh of heat on average. Its efficiency drops in hard frost, and it performs best with low-temperature emitters.
| Item | 2026 range |
|---|---|
| Air-to-water heat pump, 8 to 12 kW | €6,000 to €9,000 |
| Installation and connections | €3,000 to €5,000 |
| Adapting the heating circuit | €0 to €4,000 |
| Total excl. VAT | €9,000 to €18,000 |
| VAT at 6% (home over 10 years old) | €540 to €1,080 |
| Total incl. VAT | €9,540 to €19,080 |
Strengths: no fossil fuel, a natural fit with solar panels, and with a reversible model often the option to cool the house in summer. Weaknesses: a higher upfront cost, the noise of the outdoor unit, which needs a carefully chosen spot, and an electricity bill that climbs fast in a poorly insulated house.
The gas condensing boiler
It burns natural gas and recovers heat from the flue gases through a heat exchanger. Its efficiency is clearly better than an old boiler's, and it works just as well in a poorly insulated house.
| Item | 2026 range |
|---|---|
| 24 kW condensing boiler | €2,200 to €3,500 |
| Installation and connections | €1,500 to €3,000 |
| Flue (if replaced) | €600 to €1,500 |
| Total excl. VAT | €4,300 to €8,000 |
| VAT at 21% (since 29 July 2025) | €903 to €1,680 |
| Total incl. VAT | €5,203 to €9,680 |
Strengths: an investment two to three times lower, performance that does not depend on the weather, servicing every heating engineer knows. Weaknesses: fossil gas, ever stricter rules, compulsory periodic servicing and no cooling.
What a year of heating costs
Take a 100 m² house that needs 9,000 kWh of heat a year. With an average efficiency of 3.2, the heat pump uses about 2,800 kWh of electricity. The condensing boiler, with an efficiency close to 100%, burns about 9,000 kWh of gas.
The rule that follows is simple: as long as a kWh of electricity costs less than 3.2 times a kWh of gas, the heat pump heats more cheaply. Illustrative example, to redo with your own tariffs: at €0.35 per kWh of electricity and €0.11 per kWh of gas, the heat pump costs about €985 a year and the boiler about €990. Practically level. Solar panels tip the balance towards the heat pump, since part of the electricity no longer has to be bought.
Over 15 years, without aid
Illustrative example for the same house, without any aid, at the tariffs above:
| Air-to-water heat pump | Condensing boiler | |
|---|---|---|
| Investment incl. VAT | €14,500 (6% VAT) | €7,440 (21% VAT) |
| Heating per year | €985 | €990 |
| Servicing per year | €80 | €180 |
| Total over 15 years | €30,475 | €24,990 |
Without aid and at constant tariffs, the boiler stays cheaper over 15 years, by about €5,500 in this example. The gap narrows if you generate your own electricity, if gas prices rise faster than electricity prices, or if your project qualifies for Rénopack in Wallonia. Weigh the regulatory outlook too: a gas boiler fitted today will have to run for another fifteen years or so under rules that keep tightening.
The real referee: insulation
In a well-insulated house with low-temperature radiators or underfloor heating, the heat pump has every chance. In a moderately insulated house, both options hold up, and a heat-loss calculation settles it better than a hunch. In a home that leaks energy, insulate first: a heat pump would use too much there, and a new boiler would burn a lot of gas. Our guide to the PEB in Wallonia explains how to read your home's label.
Three questions to ask yourself
Is my home insulated enough?
If not, start there. A heat pump in a house that loses its heat works badly, and the insulation work will change the power you need anyway.
Do I have access to mains gas?
If your street is not connected and you heat with oil or propane, the connection makes the boiler more expensive. The heat pump then often becomes the logical choice.
How long will I stay?
If you sell within five years, the boiler, cheaper to buy, pays for itself faster. For fifteen years or more, a heat pump combined with good insulation is the most consistent path, especially as the announced PEB requirements in Brussels and Wallonia get stricter.
Choosing the installer
For a heat pump, ask whether the installer is RESCert certified, the certification for renewable energy system installers recognised by the three regions, and whether they hold the separate approval needed to handle refrigerants. For a boiler, check that they are qualified for your fuel. In both cases, insist on a power calculation rather than an estimate by eye, and a quote that clearly separates the lines at 6% and at 21%.
On Batizzy, you describe your project once and heating engineers in your area reply with their quote, which you compare side by side. Find a heating engineer, read our guide to heat pump prices or the one on 6% VAT.