Webasto Air Top Pro 25 Diesel 24V Heater Kit with Rheostat Controller

24V Diesel Air Heating for Heavy-Duty Trucks, Buses, and Work Equipment

The Webasto Air Top Pro 25 Diesel 24V Heater Kit with Rheostat Controller is engineered for compatible 24V diesel vehicles such as commercial trucks, buses and off-highway equipment. This factory kit (5014431A) includes Rheostat control and provides stepless 0.7–2.0 kW (2,400–7,000 BTU/h) cabin heating, plus a 2.5 kW (8,500 BTU/h) boost mode for up to six hours. It is Webasto's designated replacement kit for Air Top 2000 STC P/N 5012553A.

Benefits & Everyday Use

• Purpose-built for 24V systems: A heater kit suited to commercial-vehicle electrical architectures rated at 24V.
• Cabin heat while parked: Helps keep operators comfortable during breaks without extended engine idling.
• Stable temperature control: Stepless 0.7–2.0 kW operation to balance comfort and energy use.
• Rapid warm-up: 2.5 kW (8,500 BTU/h) boost mode for up to six hours.
• Lower-noise operation: Brushless EC motor and redesigned blower for quiet eco-mode heating.
• Work at elevation: Automatic altitude adjustment useful for trucks, buses and equipment operating on mountain routes.
• Included Rheostat Controller: Straightforward heating control without a separate controller selection.

Who Is This Heater Best For?

Choose this version when the vehicle has a 24V electrical system and an approved diesel fuel supply. Its small size and engine-off heating capabilities make it useful for a wide range of commercial and industrial applications, subject to proper installation.

• Heavy-duty trucks and commercial cabs: Heating during driver rest periods, loading stops and overnight parking.
• 24V buses and passenger transport vehicles: Supplemental cabin or operator-area heating where installation is approved.
• Construction vehicles: Operator comfort in stationary machinery and harsh job-site conditions.
• Agricultural equipment: Cabin heating in compatible 24V tractors and other off-highway machines.
• Fleet and specialty vehicles: Heating for utility trucks and vocational equipment configured with 24V systems.
• Work vehicles traveling at altitude: Automatic compensation for elevation changes without manual recalibration.

Technical Specifications

• Fuel: Diesel; manufacturer-specified paraffinic fuels (HVO/GTL).
• Rated Voltage: 24V DC (not suitable for a standard 12V-only electrical system).
• Continuous Heat Output: 2,400–7,000 BTU/h (0.7–2.0 kW).
• Fuel Consumption: 85–305 mL/h (manufacturer technical data).
• Electrical Power Consumption: Maximum 21 W (heater specification).
• Included Controller: Rheostat Controller.
• Boost Mode: 8,500 BTU/h (2.5 kW), for up to 6 hours.
• Ambient Operating Temperature: -40°F to 104°F (-40°C to 40°C).
• Altitude Capability: Automatic adjustment; operation up to approximately 18,045 ft (5,500 m), with maximum heating output available up to approximately 9,843 ft (3,000 m).
• Heater Dimensions (L × W × H): 12.6 × 5.0 × 4.9 in (321 × 127 × 124 mm).
• Heater Weight: 6.5 lb (2.95 kg); this is not the packaged kit or shipping weight.
• Mounting: Can be installed inside the vehicle or externally on the chassis, subject to Webasto installation requirements.
• Mechanical Interface: Retains the Air Top 2000 STC footplate and air inlet/outlet diameters; overall heater dimensions differ.
• Electrical Interface: Heater-side 500 mm wiring harness with an 8-pin connector and a separate 1,000 mm dosing-pump cable, or the manufacturer-specified integrated harness arrangement.
• Communications: W-Bus, LIN and CI-Bus; CAN J1939 implementation is identified by Webasto as forthcoming.
• Conformity: ECE R10, ECE R122 and CE; designed with cybersecurity requirements according to ISO/SAE 21434.

Included Factory Kit

This is a single factory configuration, so there is no controller selection on this product page. Confirm exact supplied ducting, wiring and installation components before ordering. No separate 24V MultiControl heater kit is identified among the initial North American launch part numbers.

Webasto Air Top Pro 25 vs. Air Top 2000 STC

Compared with the previous-generation Air Top 2000 STC, the Air Top Pro 25 expands the low-output operating range, adds a 2.5 kW boost mode and introduces automatic altitude adjustment. The specifications below compare the same fuel and voltage category, not every kit component.

Air Top 2000 STC Replacement Part Numbers

Webasto identifies 5014431A as the replacement kit for the 24V diesel Air Top 2000 STC P/N 5012553A. The table below also covers the other original and new factory-kits for reference.

Webasto lists MultiControl kits 5014494A (diesel 12V) and 5014495A (gasoline 12V) as new factory configurations rather than assigning them a direct Air Top 2000 STC predecessor part number.

The shared mechanical interface makes upgrades easier to plan, but the new wiring system and slightly larger heater housing must be checked before replacing a 24V Air Top 2000 STC.

Browse Webasto Manuals & Technical Documentation

FAQs

Will my Webasto heater still keep me warm at high altitudes?

Yes. The Air Top Pro 25 automatically adjusts for altitude and is specified to operate up to approximately 18,045 ft (5,500 m). Webasto states that maximum heating output is available up to approximately 9,843 ft (3,000 m). Above that elevation, the heater can continue operating within its stated range, but peak heat output may be reduced. Actual cabin comfort also depends on outside temperature, insulation and installation.

Can I replace my Webasto Air Top 2000 STC with the new Air Top Pro 25 without modifying my setup?

Not necessarily. Webasto retains the Air Top 2000 STC footplate and air inlet/outlet diameters, which helps with replacement installations. However, the heater body is not exactly the same size: the Air Top Pro 25 measures 321 × 127 × 124 mm, compared with 311 × 120 × 121 mm for the Air Top 2000 STC. The electrical connector, wiring harness arrangement and control interfaces also differ. Plan to check physical clearance, wiring and controller compatibility; do not assume a plug-and-play swap or reuse of every existing component. Follow Webasto installation instructions or consult a qualified installer.

Can I connect this 24V heater to a 12V vehicle?

No. This kit is specified for 24V DC electrical systems. For a compatible 12V diesel vehicle, choose the corresponding Air Top Pro 25 Diesel 12V heater kit instead.

Which controller is included with part number 5014431A?

Webasto Air Top Pro 25 kit 5014431A comes with a Rheostat Controller. It is sold here as one fixed factory configuration.

Is this heater suitable for a fleet truck or construction machine?

The 24V diesel version is intended for suitable trucks, buses, construction equipment, agricultural machinery and specialty vehicles. Confirm the equipment voltage, mounting space, fuel supply, exhaust routing and applicable installation requirements.

Is a new diagnostic tool needed for servicing the Air Top Pro 25?

Webasto identifies its Webasto System Diagnostics (WSD) platform as the diagnostic system for the Air Top Pro 25, with diagnostic kit part number 9044777A. This is a service tool, not a normal requirement for switching the heater on.