How to Choose a Webasto Heater
Posted by [email protected] on 29th Jul 2026
Choosing the right Webasto heater depends on what you need to heat, the size of your vehicle, the available fuel and voltage, and the required heating output. This guide compares Webasto air heaters, coolant heaters, and combined air-and-water systems for vans, RVs, trucks, boats, and commercial vehicles.
Last updated: July 2026
Webasto Heaters Reliable Heating on the Go
Webasto is a German-based manufacturer of high-quality heating, air conditioning, and sunroof solutions for a variety of applications. Their air and water heaters are regarded as some of the best in the world for being silent, fuel-efficient, and cost-effective. Webasto heaters are known for being long-lasting and low-maintenance, with spare parts readily available when necessary.
Popular Webasto Air Heaters
Webasto Air Top 2000 STC 12V
The Webasto Air Top 2000 STC 12V air heater is a community favorite among vanlifers. Available in both petrol and diesel variants, this 2KW heater is ideal for any mid-sized RV or van, like the Sprinter or ProMaster. The budget-friendly Air Top 2000STC is fuel-efficient and quiet, reliably heating your cabin at altitudes up to 7,200 feet (2,200 m). Its compact design provides greater installation flexibility, while widely available documentation and replacement parts can simplify maintenance.
- Fuel Type: Diesel or Gasoline, depending on configuration
- Rated Voltage: 12V or 24V, depending on configuration
- Top Altitude: 7,200 ft (2,200 m)
- Heating Power: 6,800 BTU (2,000 W)
- Fuel Consumption: 0.026 - 0.05 gal/h (0.12 - 0.24 l/h)
Webasto Air Top EVO 40
If you’re looking for a reasonably-priced heater with extra heating power, the Webasto Air Top EVO 40 is for you. This is the most popular 4KW Webasto heater and has a range of features that make it ideal for vanlife. Thanks to an upgraded control system and optimized combustion, the Air Top EVO 40 works silently and efficiently. An integrated altitude sensor lets the heater function reliably at higher altitudes. Low fuel consumption, versatility, durability, and exceptionally quiet operation make the EVO 40 one of the best 4KW air heaters.
- Fuel Type: Diesel or Gasoline, depending on configuration
- Rated Voltage: 12V or 24V, depending on configuration
- Top Altitude: 7,200 ft (2,200 m)
- Heating Power: 13,640 BTU (4,000 W)
- Fuel Consumption: 0.04 - 0.09 gal/h (0.18 - 0.43 l/h)
Webasto Air Top Evo 55
The Webasto Air Top Evo 55 is a high-output air heater designed for larger vans, RVs, commercial vehicles, and other spaces that require more heating power. With up to 5 kW of heat output, it provides faster warm-up and greater airflow than the Air Top 2000 STC and Air Top Evo 40.
The Evo 55 is a good choice for larger or less-insulated vehicles, particularly in colder climates. Despite its higher output, the heater is designed for efficient fuel consumption and quiet operation. It is available in diesel configurations and can be paired with different controllers depending on the installation kit.
- Fuel Type: Diesel or Gasoline, depending on configuration
- Rated Voltage: 12V or 24V, depending on configuration
- Top Altitude: 7,200 ft (2,200 m)
- Heating Power: 17,000 BTU (5 kW)
- Fuel Consumption: 0.06 - 0.17 gal/h (0.18 – 0.67 l/h)
How Much Heating Power Do You Need?
The right heating output depends on the size of your vehicle, the quality of its insulation, the outside temperature, and how frequently doors are opened. Choosing the most powerful heater is not always the best option: an oversized heater may spend more time operating at low output, while an undersized model may struggle to maintain a comfortable temperature.
A 2 kW air heater such as the Webasto Air Top 2000 STC is generally suitable for small and medium-sized vans, including many 144-inch and 170-inch Sprinter conversions with good insulation.
For larger vans, RVs, or vehicles with limited insulation, the 4 kW Webasto Air Top Evo 40 provides more heating capacity and faster warm-up.
The 5 kW Webasto Air Top Evo 55 is better suited to larger cabins, commercial vehicles, colder climates, and applications that require higher airflow or faster recovery after doors are opened.
If you also need engine preheating, a hydronic heating system, or domestic hot water, consider a Webasto coolant heater or a combined air-and-water heater instead of choosing an air heater based on output alone.
Webasto Air Heater Comparison
| Feature | Air Top 2000 STC | Air Top Evo 40 | Air Top Evo 55 |
|---|---|---|---|
| Maximum heating output | 6,800 BTU (2 kW) | 13,650 BTU (4 kW) | 17,000 BTU (5 kW) |
| Best for | Small and medium-sized insulated vans | Larger vans and RVs | Large cabins and commercial vehicles |
| Typical applications | Camper vans, smaller RVs, truck cabs | Large vans, RVs, boats, commercial vehicles | Large RVs, work trucks, buses, boats, specialty vehicles |
| Fuel options | Diesel or gasoline, depending on configuration | Diesel or gasoline, depending on configuration | Diesel or gasoline, depending on configuration |
| Voltage options | 12V or 24V, depending on configuration | 12V or 24V, depending on configuration | 12V or 24V, depending on configuration |
| Relative cabin warm-up | Suitable for smaller spaces | Faster in larger spaces | Fastest option for large spaces |
| Installation space | Most compact option | Requires more installation space | Requires more installation and ducting space |
| Primary advantage | Compact size and low fuel consumption | Balance of output, size, and efficiency | High output and greater airflow |
Air, Coolant, or Combined Heater: Which Type Do You Need?
Before choosing a Webasto heater, consider what you need to heat. Webasto Air Top heaters warm the air inside a vehicle, while Thermo Top and Thermo Pro coolant heaters heat the vehicle’s coolant. Dual Top systems combine cabin heating with domestic hot water production.
Webasto Air Heaters
Air heaters transfer heat directly into the cabin through warm-air ducting. They are a practical choice when your main goal is to heat the living or working space inside a van, RV, truck, or boat. The Air Top 2000 STC, Air Top Evo 40, and Air Top Evo 55 cover different vehicle sizes and heating requirements.
Webasto Coolant Heaters
Webasto Thermo Top and Thermo Pro heaters warm coolant rather than blowing hot air directly into the cabin. Depending on how the system is designed, a coolant heater can be used to preheat an engine, supply heat through radiators or fan-assisted heat exchangers, and support a hot-water system through a suitable calorifier or heat exchanger.
The Thermo Top Evo is a compact option for passenger vehicles, vans, and lighter-duty applications. The Thermo Pro range is designed for applications that require greater heating capacity, including commercial vehicles, trucks, buses, and heavy-duty equipment.
Need engine preheating or a hydronic heating system? Explore Webasto coolant heaters.
Webasto Combined Air and Water Heaters
For RV and motorhome owners who need both cabin heating and domestic hot water, a combined system such as the Webasto Dual Top may be more convenient. These systems are different from standard coolant heaters because they are designed to provide warm air and heat a domestic water supply within one installation.
Webasto Dual Top Heaters
Webasto Dual Top ST 6
The Dual Top ST 6 is a combined air heater and water heater in one unit. This versatile heater can be used to keep your cabin warm, provide hot water, and even heat your floors. With 6KW of heat output, this powerful yet fuel-efficient diesel heater will easily keep you warm.
It’s intelligently designed to be mounted externally, saving you precious space inside your caravan or RV. The ease of use, fuel efficiency, and compact design make the Dual Top ST 6 an easy choice for those who are looking for a reliable source of heat for their motorhome.
- Fuel Type: Diesel
- Rated Voltage: 12V
- Top Altitude: 7,200 ft (2,200 m)
- Heating Power: 20,470 BTU (6,000 W)
- Fuel Consumption: 0.05 - 0.17 gal/h (0.22 - 0.77 l/h)
- Dimensions: 20.8 x 13.9 x 10.1 in (530 x 352 x 256 mm)
Webasto Dual Top ST 8
The Webasto Dual Top ST 8 is the most powerful combined air and water heater on the market. This powerful diesel heater provides 6,000 watts for air heating and features an integrated 2KW coil for water heating.
The Dual Top ST 8 is perfect for large motorhomes with running water like an internal shower or a kitchen tap. Mount the Dual Top ST 8 externally to save precious cabin space, and enjoy the comforts of reliable heating at altitudes up to 7,200 feet (2,200 m). Heat your cabin and your water independently to your desired temperature with one fuel-efficient heater.
- Fuel Type: Diesel
- Rated Voltage: 12V
- Top Altitude: 7,200 ft (2,200 m)
- Heating Power: 20,470 BTU + 6,800 BTU (6 kW + 2 kW)
- Fuel Consumption: 0.05 - 0.17 gal/h (0.22 - 0.77 l/h)
- Dimensions: 20.8 x 13.9 x 10.1 in (530 x 352 x 256 mm)
Which Webasto Heater Should You Choose?
Choose an Air Top heater when you primarily need cabin heat, a Thermo Top or Thermo Pro coolant heater when you need engine preheating or a hydronic system, and a Dual Top system when your RV requires both cabin heating and domestic hot water. Before ordering, confirm the required output, fuel type, voltage, altitude capability, and installation configuration.
