Replacing your gas boiler with a heat pump in Luxembourg: the complete 2026 guide

Natural gas vs heat pump: is switching really worth it in Luxembourg?

This is the key question, and it deserves a nuanced answer. Unlike oil boilers — whose fuel costs are structurally high — recent condensing gas boilers are already efficient appliances, with an efficiency of around 105–110%. Whether switching to a heat pump pays off therefore depends on several variables specific to Luxembourg in 2026.

Gas vs electricity prices in Luxembourg in 2026: the key factor

In 2026, natural gas in Luxembourg costs around €0.10–0.13/kWh all-in (energy + Creos network charges + levies + CO₂ tax + 8% VAT). To heat a 130 m² house, a condensing boiler typically burns 15,000–20,000 kWh of gas a year, giving a bill of €1,500–2,600 depending on your contract and your insulation.

Electricity costs around €0.25/kWh in Luxembourg. But an air-to-water heat pump with an average seasonal COP of 3.2 uses 1 kWh of electricity to produce 3.2 kWh of heat — an effective cost of around €0.078 per kWh of heat, which is lower than gas.

Overall, then, the price ratio favours the heat pump, with annual savings of around 15–35% on your heating bill (roughly €275–780 a year for the 130 m² house in the example further down). That is noticeably less spectacular than switching from oil to a heat pump (where savings often exceed 45%), but it still adds up to a very significant sum over the 15–20-year lifespan of an installation.

When replacement is clearly recommended

When the decision needs more thought

The technical specifics of replacing a gas boiler with a heat pump

Technically, replacing a gas boiler with an air-to-water heat pump follows the same general pattern as replacing an oil boiler: the old boiler is removed and the new heat pump is connected to the existing heating water circuit. But with gas, several technical points need particular attention.

The existing heating circuit: an often-overlooked advantage of condensing gas

Modern condensing gas boilers (post-2000) already run at a low return temperature — generally between 40 and 50°C — to maximise condensation. This means that the heat emitters (radiators, underfloor heating) in a home with a recent condensing boiler are often directly compatible with a standard air-to-water heat pump, with no costly radiator upgrades.

If your gas boiler is older, however (pre-2000, running at a high temperature of 70–80°C), radiator compatibility must be checked — exactly as with an old oil boiler. The installer carries out a radiator output calculation to confirm that the existing radiators are large enough at a lower flow temperature.

High-temperature (HT) heat pumps: the solution for poorly insulated homes

For homes that are still under-insulated or whose radiators are too small for low-temperature operation, there are so-called « high-temperature » air-to-water heat pumps capable of producing water at 65°C or even 75°C (compared with a maximum of 55°C for a standard heat pump). These models can replace a gas boiler without touching the radiators, even old ones. Their COP is slightly lower than that of a standard heat pump (around 2.5–3.0), but they are still much cheaper to run than a gas boiler.

Domestic hot water after the replacement

The gas boiler usually produced domestic hot water (DHW), either instantaneously or via a connected cylinder. When you switch to an air-to-water heat pump, you have several options:

• DHW cylinder linked to the main heat pump: the heat pump heats a storage cylinder (200–300 litres depending on the household) during off-peak hours or when there is surplus solar PV power. This is the cheapest option to run.
• Integrated DHW module (hydrokit): some air-to-water heat pumps build hot water production directly into the indoor unit, which simplifies installation and saves space.
• Separate heat pump water heater: if the main heat pump is not sized for DHW, a stand-alone heat pump water heater (not eligible for the Klimabonus) can be installed alongside it.

Space in the boiler room: plan for it from the start

A wall-mounted gas boiler (a very common set-up in Luxembourg) is a compact appliance. Replacing it with an air-to-water heat pump means adding an indoor unit + a buffer tank + a DHW cylinder, which together take up considerably more room. The space available in your plant room or boiler room must be assessed during the installer’s visit. In homes without a basement or with a very small plant room, an experienced installer will suggest alternatives (a compact hydrokit, a tall slimline cylinder, installation in the cellar).

Technical requirements for the Klimabonus 2026

To qualify for the Klimabonus, your heat pump installation must meet all of the following technical conditions, without exception:

• Minimum COP ≥ 3.1 (air-to-water heat pump, A7/W35) or ≥ 4.3 (ground-source heat pump, B0/W35)
• Buffer tank with a minimum capacity of 30 l/kW of rated heat output (except for heat pumps with variable-speed, modulating output)
• Heat meter and dedicated electricity meter for the heat pump, both mandatory
• Hydraulic balancing of the heating system
• Noise limits: ≤ 48 dB(A) for heat pumps ≤ 5 kW, ≤ 51 dB(A) for 5–12 kW, ≤ 55 dB(A) for > 12 kW (sound power level of the outdoor unit), or ≤ 40 dB(A) at the boundary of the neighbouring plot, calculated with the official noise calculator
• Request for an acceptance inspection by the Chambre des Métiers, mandatory within one month of commissioning

What to do with your gas contract and gas installation after the replacement

This question is specific to switching from gas to a heat pump — it simply doesn’t arise for people who heated with oil. In Luxembourg, if you are connected to the Creos natural gas network and replace your boiler with a heat pump, you will need to deal with two separate formalities: cancelling your gas supply contract, and closing the supply point with Creos.

Step 1: Cancel your gas supply contract

Contact your gas supplier (Enovos/LEO Energy, SUDénergie or another supplier active in Luxembourg) to cancel your contract. The good news: under Luxembourg’s gas market rules, cancelling a natural gas supply contract is free of charge and involves no restrictive notice period for residential customers. Your supplier will arrange a final meter reading and send you a closing bill.

If you want to keep using gas for other purposes (e.g. a gas range cooker), you don’t have to cancel the contract: you can simply switch to a different type of contract or tariff, which removes the heating element of your gas supply.

Step 2: Close the supply point with Creos

Once the supply contract has been cancelled, closure and physical removal of the gas meter must be requested directly from Creos, as the distribution network operator. Creos sends a technician to cap the service connection and remove the meter. This service may be charged according to Creos’s current service tariffs.

Step 3: Decommissioning the indoor gas installation

The internal gas pipes (from the meter to the old boiler) must be properly made safe. A certified installer (approved for gas installations) isolates and caps the valves and connections, in compliance with the Grand-Ducal Regulation of 27 February 2010 on gas installations. An acceptance inspection by the Chambre des Métiers is mandatory to confirm that the gas installation has been taken out of service.

Timing and coordination

To avoid a break in heating, schedule the gas shut-off on the same day as, or within 24 hours of, the heat pump’s commissioning. Your heat pump installer can coordinate this timing with you. Some experienced installers offer a full coordination service, including notifying the gas supplier and requesting the Chambre des Métiers acceptance inspection for the gas side.

2026 grants for replacing a gas boiler with a heat pump in Luxembourg

Replacing a gas boiler with a heat pump qualifies for the same grants as replacing an oil boiler: the Klimabonus makes no distinction between fossil fuels. Here is the full breakdown of the grants you can combine in 2026.

1. Klimabonus Wunnen 2026 — €10,000 (€12,000 if ordered by 30 June 2027)

Since 1 January 2026, the Klimabonus Wunnen has paid flat-rate amounts set in euros, regardless of the installation’s output. For replacing a gas boiler with an air-to-water heat pump, the Klimabonus comes to €10,000 (€12,000 if the heat pump is ordered by 30 June 2027). In detail:

• The basic grant for installing the air-to-water heat pump
• The fossil-fuel boiler replacement bonus: since 2026, this bonus has been built directly into the base amounts
• On top of the €10,000, a bonus for adapting the existing heat distribution system where necessary (radiators): 50% of the costs, up to €2,000
• A buffer tank (≥ 30 l/kW of rated output) is an eligibility condition, except for a modulating heat pump: it does not qualify for any bonus (the +15% applies to pellet boilers)

2. Enoprimes — €1,700 to €2,500

Enoprimes, the energy suppliers’ grant programme (enoprimes.lu), pays €1,700 to €2,500 for an air-to-water heat pump in a single-family house, plus a €1,000 anniversary bonus in 2026, on top of the Klimabonus. Be careful: the application must be opened before you order the works, through a partner installer; the premium is paid about 4 weeks after approval. There is no specific Enoprime for removing a gas installation (no oil tank to dispose of).

3. Super-reduced 3% VAT rate on all the work

In Luxembourg, renovation work on your main residence, if the home is at least 10 years old, qualifies for VAT at 3% instead of 17% (tax benefit capped at €50,000 per home). On a €20,000 heat pump installation, that represents a saving of almost €2,800, applied directly on the contractor’s invoice once the AED has approved it (your installer applies before the work starts and you countersign).

4. Municipal grants — €500 to €6,000 depending on the commune

For an air-to-water heat pump, 84 of the 100 communes add €500 to €6,000 to the Klimabonus, and 11 others ask you to contact them. The maximum, €6,000, is paid in Luxembourg City and Schifflange, ahead of Differdange (€5,000); the median is €1,200 (Klima-Agence simulator, September 2026). Exact amount: your commune’s grant.

Indicative amounts for a typical home in Luxembourg. As the Klimabonus 2026 amounts are set by the law of 24 July 2026, published in the Official Journal, check the exact amounts on guichet.public.lu or klima-agence.lu before finalising your application.

Costs, savings and payback — gas boiler → heat pump

Here is a realistic projection based on installations carried out in Luxembourg in 2025–2026 for switching from a gas boiler to an air-to-water heat pump. Costs include removing the gas boiler, decommissioning the gas installation, the heat pump + hydrokit + buffer tank + DHW cylinder, hydraulic balancing and commissioning.

Gross costs exclude VAT; net cost includes VAT at 3% (after AED approval). Grants: Klimabonus of €12,000 for a heat pump ordered by 30 June 2027 (€10,000 after that, i.e. €2,000 more on the net cost); for the third profile, add the bonus for adapting the heat distribution system (50% of the costs, up to €2,000). Enoprimes and municipal grants are not included. Savings are calculated with the assumptions of the example below (gas €0.10–0.13/kWh, 107% efficiency; electricity €0.25/kWh, seasonal COP 3.2), i.e. 1.5–4.3 cents per kWh of heat, for heat demands of around 9,000, 18,000 and 27,000 kWh/year. Indicative figures. The payback period is much longer than for replacing an oil boiler because the annual savings are smaller: gas is already cheaper than heating oil, so the difference in bills is less spectacular. On the other hand, the installation cost is the same, and so are the Klimabonus grants. If your boiler has to be replaced anyway, compare the heat pump’s net cost with the price of a new gas boiler instead, which receives no grant: the gap is then much smaller.

Annual heating costs compared: condensing gas boiler vs air-to-water heat pump

A worked example for a 130 m² house with an annual heat demand of 18,000 kWh:

The hybrid heat pump option: keeping the gas boiler as temporary backup

You don’t have to break with gas completely and immediately. There is a third, often underrated route: the hybrid heat pump, which pairs an air-to-water heat pump with your existing gas boiler or with a new low-output gas boiler.

How does a hybrid heat pump + gas system work?

The principle is simple: the air-to-water heat pump provides all the heating in normal weather conditions (generally down to −5°C or −7°C depending on the model), and the gas boiler automatically takes over during severe cold spells or periods of high simultaneous demand (heating + hot water). A smart control module manages the switchover in real time based on the outdoor temperature, the heat pump’s instantaneous COP and energy prices.

This system makes particular sense in the following situations:

• Older house with high-temperature radiators that are not compatible with a standard heat pump — the gas boiler tops up the heating on very cold days
• Co-ownership (condominium) where installing a single high-output heat pump raises noise or siting issues
• Owners who want a gradual transition, with maximum heating security during the adjustment period

Klimabonus conditions for a hybrid system

The Klimabonus 2026 only subsidises a hybrid heat pump if the whole system is non-fossil: a heat pump + gas boiler hybrid does not qualify. An eligible hybrid must meet the following conditions:

• The backup is not fossil-fuelled (no gas or oil): the hybrid system is entirely non-fossil
• The heat pump covers at least 70% of the home’s annual heat demand (calculated and documented)
• The heat pump is able to run on its own, without the backup

In practice, keeping the gas boiler as backup means losing the heat pump’s Klimabonus (€10,000, or €12,000 if ordered by 30 June 2027). To receive the grant, the heat pump must replace the gas boiler and be sized to heat the home on its own.

The replacement project step by step, from A to Z

Special cases: apartment, co-ownership, underfloor heating, recent house

I live in an apartment with its own wall-mounted gas boiler

This is the most common set-up in Luxembourg apartment buildings built between 1990 and 2015: each apartment has its own wall-mounted gas boiler. Replacing it with an air-to-water heat pump is technically possible, but means installing an outdoor unit on the façade, balcony or terrace. In a co-ownership (condominium), this generally requires:

• Approval from the co-owners’ general meeting (a majority of the votes of all co-owners, Art. 16 b of the amended law of 16 May 1975)
• A check of the co-ownership rules and municipal regulations on installations visible on the façade
• A prior noise calculation to confirm that noise limits are respected with regard to the neighbouring apartments

Compact, low-output air-to-water heat pumps designed specifically for apartments are available on the market (some models sit entirely indoors or are built in at plinth level). Ask your installer to present the solutions suited to your set-up.

Communal gas heating in a co-ownership

If the building has a central gas boiler room, the replacement must be voted on at the general meeting. Options at building level include a communal ground-source heat pump, connection to a district heating network (there are some in Luxembourg City, Kirchberg, Esch-sur-Alzette…) or a communal biomass boiler. These projects qualify for specific Klimabonus grants for multi-unit projects.

House with underfloor heating and a condensing gas boiler: the ideal profile for a heat pump

If your house has water-based underfloor heating (low temperature, 28–35°C) fed by a condensing gas boiler, you have the most favourable profile there is for a heat pump installation. Underfloor heating runs at exactly the ideal temperature for an air-to-water heat pump, which maximises the seasonal COP (sometimes up to 4.5–5 in spring and autumn) and minimises electricity use. In this case, the payback period will be at the bottom of the range in the table above, depending on your initial consumption.

Recent house built with gas heating (less than 10 years old)

Since 1 January 2026, with the age requirement scrapped, you are eligible for Klimabonus grants even if your house and your gas boiler are recent. The economic question remains open, though: if your boiler works perfectly and your home is well insulated (class B or A), the payback period will be long, often more than 15 years (see the table above). If you are also considering installing solar panels, however, combining the two projects speeds up payback and lets you pool the paperwork.

Frequently asked questions about replacing a gas boiler with a heat pump in Luxembourg