Installing a diesel air heater in a Sprinter van is one of the most impactful upgrades for cold-weather van life. A properly installed heater provides reliable cabin warmth down to -40°F while consuming minimal fuel and battery power. This guide walks through the installation process using an HLN Aerolyn PRO as the example, though the general steps apply to most diesel air heaters.

Before you start

Gather your tools: drill with hole saw bits, wire crimpers, cable ties, a wrench set, and sealant for weatherproofing the drilled holes. The HLN Aerolyn ships with a complete installation kit including all necessary brackets, ducting, fuel line, exhaust pipe, and electrical harness.

Plan your layout before drilling any holes. You need to determine four things: where the heater unit will sit, where the exhaust will exit underneath the van, where the fuel pickup will connect to your fuel source, and where the control panel will mount inside the cabin.

Step 1: Choose the heater location

The most common mounting location in a Sprinter van is under a bench seat, under the bed platform, or in a lower cabinet. The heater needs adequate airflow around it, so avoid mounting it in a completely sealed compartment.

Key requirements for the location: the exhaust port must be accessible to route downward through the floor, the air intake and outlet must have clear paths, and you need access for maintenance (cleaning the combustion chamber and replacing glow plugs).

Step 2: Mount the heater unit

Use the included mounting bracket to secure the heater to the van floor or to a structural support. The heater should be mounted level.

Drill the necessary holes through the van floor for the exhaust pipe, combustion air intake, and fuel line. Apply sealant around each penetration to prevent water ingress. The exhaust must exit below the van floor and point downward or to the side — never upward.

Step 3: Install the exhaust system

Route the exhaust pipe from the heater downward through the floor. The exhaust must exit in an area with good airflow and away from any openings into the cabin (windows, doors, vents). Install the exhaust silencer for quieter operation — HLN includes an integrated silencer option specifically for the Aerolyn series.

The exhaust tip should extend at least two inches below the van floor. Secure all exhaust connections with clamps and check for leaks. This is a safety-critical step — exhaust leaks can introduce carbon monoxide into the cabin.

Step 4: Connect the fuel supply

You have two options for fuel supply: tap into the Sprinter's main diesel tank using a fuel pickup, or use a separate dedicated fuel tank.

For the main tank option, install the fuel pickup through an existing port or drill a new access point. For a separate tank, HLN offers an 8-liter fuel tank with a built-in fuel scale that works well for van installations.

Route the fuel line from the tank to the fuel pump, then from the fuel pump to the heater. The height difference between the fuel tank liquid level and the fuel pump must not exceed 1 meter. The HLN Aerolyn is compatible with Espar/Eberspacher ultra-quiet fuel pumps if you want the quietest possible operation.

Step 5: Electrical wiring

Connect the heater's power cable to the van's battery system. A 2kW heater like the Aerolyn 2000 PRO draws approximately 10-30 watts during operation (after startup), making it very efficient on battery power. At the starting and shutting down stage, a power draw of about 150 watts is possible.

Use appropriate gauge wire for the distance from battery to heater, an inline fuse is alreadt provided in the HLN set. Connect the control panel wiring and mount the WiFi controller in a convenient location on the cabin wall.

Step 6: Install air ducting

Connect the hot air outlet ducting to direct heated air where you want it in the cabin. You can run ducting to multiple outlets — for example, one vent near the sleeping area and another in the main living space. The first hot air outlet should be with in 2 meter / 6 feet from the the heater.

The cold air can draw from either the cabin interior or from outside. Drawing air from inside would recirculate and reheat cabin air, thus achieve maximum efficiency.

Step 7: Test the system

Before your first trip, run through a complete startup and shutdown cycle. The first startup may produce some smoke as manufacturing residues burn off — this is normal and clears within a few minutes.

Verify that the WiFi controller connects to the SmartLife app and that you can start, stop, and set temperatures remotely. Check all exhaust connections one more time for leaks.

Common installation mistakes to avoid

Do not mount the exhaust exit point near any cabin opening. Do not run the fuel line near heat sources. Do not skip the inline fuse on the power connection. Do not mount the heater in a sealed compartment without airflow. Do not forget to apply sealant around floor penetrations.

A properly installed diesel heater should provide years of reliable service. The HLN Aerolyn PRO brushless motor is rated for over 5,000 hours, and with minor annual maintenance and care, such as running the heater on high for 15 minutes during the months not used, the heater will perform consistently season after season.