Which water heater should you choose in Luxembourg? The 2026 Guide
Water heaters account for up to 30% of your energy consumption. Solar, thermodynamic or electric water heaters... Here's how to choose the best one for your situation.
Key points to remember
- Electric water heaters are the most widespread in Luxembourg, but also the most energy-intensive.Thermodynamic models consume up to 3 times less electricity.
- Solar water heaters offer the greatest energy savings (up to 60% of needs covered) but requires the highest initial investment.
- The volume of the water heater must be adapted to the size of the household: from 50-75L for one person to 200-300L for 5 people or more.
What are the different types of water heater?
Electric water heaters
This is the most traditional type of water heater and the one most commonly used in Luxembourg (apart from gas or oil-fired systems).
The principle is simple: an electric resistance heats the water in an insulated tank. There are two main types:
- Le storage water heaters (cumulus): stores hot water in an insulated tank and keeps it at the right temperature.
- Le instantaneous water heater heats water on demand, without storage, but requires high electrical power for rapid heating
Models and installation are simple and inexpensive. Heating can be programmed and, above all, these units can be installed anywhere, as long as they can be connected to the electricity network.
On the other hand, they are expensive in terms of electricity (especially in a context of rising kWh prices in Luxembourg). They can also take a long time to heat up, and their energy efficiency is not very attractive compared with other solutions.
The thermodynamic water heater
Le thermodynamic water heater is becoming increasingly popular in Luxembourg. It works on exactly the same principle as a heat pump It uses calories from the air to heat water, consuming up to three times less electricity than a conventional electric water heater.
- It offers considerable energy savings
- It has a long service life
- But this type of model is more expensive to buy and installation can be complex.
Read our full guide to thermodynamic heating to find out more.
Solar water heaters
Solar water heaters use the sun's energy, captured by thermal solar panels, to heat water. It generally consists of a black panel topped by a stainless steel tank (although the tank is not always present). A back-up system (usually electric) takes over in the event of insufficient sunlight.
- This method of heating domestic hot water is very environmentally friendly.
- It offers huge energy savings (covering up to 60% of hot water needs)
- It has a very long life
- But installation is complex, the models are expensive, and you need a clear roof.
To find out more: see our complete guide to solar water heaters in Luxembourg
Thermal water heaters (gas, oil)
A gas or oil-fired water heater (also known as a "bath heater") heats water using a burner fuelled by natural gas or propane. They come in instantaneous or storage versions.
This type of water heater is usually coupled to your boiler.
- Generally gas or oil if you live in a house
- Most apartment blocks are gas-fired
These water heaters are being installed less and less because they are not environmentally friendly, are less efficient than solar or thermodynamic alternatives, and require much more maintenance.
What volume for my home?
It is important to choose a water heater that is perfectly sized for the needs of your household:
- If you choose a model that is too small, you won't have enough hot water (and some people will have to shower in lukewarm water)
- If you choose a model that is too largeIf you use a hot water boiler, you're going to have to heat far too much water for what you really need. As a result, you'll consume a lot of energy (and energy is expensive!).
Here are the average requirements in Luxembourg, according to household composition:
| Household composition | Recommended capacity |
| 1 person | 50-75 litres |
| for 2 people | 75-100 litres |
| 3 people | 100-150 litres |
| 4 people | 150-200 litres |
| 5 people or more | 200-300 litres |
These figures are indicative and may of course vary according to your consumption habits. If you are in the habit of taking baths regularly, plan on a larger volume.
Budget and constraints in Luxembourg
The total cost of a water heater in Luxembourg includes not only the purchase and installation price, but also the annual consumption and maintenance costs.
Here is a table comparing the different systems:
| Type of water heater | Purchase price and installation | Annual cost of use (4 people) |
| Electric | €800 – €1,800 | €1,100 – €1,500 |
| Thermodynamics | €3,500 – €7,000 | €550 – €850 |
| Solar | €9,000 – €15,000 | €250 – €450 |
| Gas | €1,300 – €3,700 | €1,250 – €1,700 |
In Luxembourg, the installation of a water heater must comply with national electrical and plumbing safety standards. Here are some specific points to consider:
- For flats, co-ownership regulations may restrict certain installations (check with your building manager to find out what type of water heater you can install)
- For thermodynamic water heaters, provide a space of at least 20m³ or an outside air intake (as this type of system needs to draw in air to operate).
- For solar water heaters, check the orientation and available roof surface area
- For gas-fired water heaters, make sure the network is available and provide a gas evacuation system.
Conclusion: which water heater should you choose in Luxembourg?
There are many factors to consider when choosing a water heater in Luxembourg: your hot water requirements, the layout of your home, your budget and the tax benefits available.
For most households in Luxembourg, the thermodynamic water heater currently represents the best compromise between initial investment, ecological performance and tax benefits.
For larger families or new buildings with good exposure, the solar water heater can be particularly advantageous thanks to the considerable support it receives, despite Luxembourg's moderate level of sunshine.
Le electric water heater remains relevant for small homes or as a transitional solution, while the gas water heater can be considered in areas well served by the Luxembourg gas network.
The best thing is to consult a professional heating engineer - he'll help you make the best choice.
Frequently asked questions: everything you need to know about water heaters in Luxembourg
What is a storage water heater and how does it differ from an instantaneous water heater?
A storage water heater (also known as a cumulus) stores hot water in an insulated tank and keeps it at a constant temperature. The hot water is therefore available continuously. An instantaneous water heater, on the other hand, heats the water directly as it passes through, without storage, saving space but requiring high electrical power for rapid heating.
What is a gas or oil-fired water heater?
A thermal water heater (gas or oil) heats water using a burner fuelled by natural gas, propane or oil, often coupled to an existing boiler. They are becoming less popular because of their low energy efficiency compared with environmentally-friendly alternatives.
What size of water heater should I choose, depending on the size of my household?
The ideal volume for your water heater depends directly on the number of people in your household: 50-75 litres for one person, 75-100 litres for two people, 100-150 litres for three people, 150-200 litres for four people and 200-300 litres for five people or more.
Which type of water heater offers the best value for money in Luxembourg?
In Luxembourg, thermodynamic water heaters generally represent the best compromise between initial investment, ecological performance and tax benefits for most households. For new-build properties with good exposure or large families, solar water heating can be particularly advantageous thanks to the substantial subsidies available.