Reliable Diesel Cabin Heat for Canadian Boaters
The Eberspaecher Airtronic D4 is a forced-air diesel heater engineered specifically for the marine environment. It draws a small amount of diesel from your main fuel tank and converts it into clean, dry cabin heat — eliminating the moisture problems associated with propane heaters and keeping your boat comfortable during cold Canadian shoulder seasons, fall haul-out prep, or early spring commissioning weekends.
With over 30 years of successful marine installations worldwide, the Airtronic D4 has proven itself in demanding offshore conditions. Whether you're cruising the coast of British Columbia, navigating the Great Lakes in October, or living aboard in a Nova Scotia harbour through the autumn, this heater provides dependable warmth without the complexity of a hydronic system.
Four Output Levels to Match Your Heating Needs
The Airtronic D4 offers four discrete thermal output settings, allowing you to match heat production to conditions. On a mild evening, the lowest setting of 3,400 BTU provides gentle background warmth with minimal fuel and electrical draw. When temperatures plummet, the full 13,650 BTU boost setting rapidly heats the entire cabin volume. The two intermediate settings — approximately 6,800 and 10,200 BTU — give you fine control over comfort and economy.
This variable output means the heater isn't simply on or off. The included Digi-Controller with diagnostics lets you set your desired cabin temperature, and the system modulates between output levels to maintain it. The result is consistent warmth without temperature swings.
Complete Kit — Everything for Installation
Unlike bare heater units that require sourcing individual components, this kit arrives with all the parts needed for a full marine installation. The ducting, exhaust, fuel lines, and controller are all included, saving time and ensuring compatibility.
- 3-1/2" x 30 feet flexible ducting
- 3" x 13 feet flexible ducting
- Loose duct fittings
- 2 Y-pieces for splitting airflow to multiple cabins
- 2 closeable vent outlets
- 1 non-closeable vent outlet (required for safe operation)
- 25 feet of copper fuel lines
- Fire-resistant fuel adaptors
- 10 feet of double-wall exhaust tubing
- Digi-Controller with diagnostics
Installation Considerations for Sailboats and Powerboats
On a sailboat, the compact Airtronic D4 typically mounts in a stern or cockpit locker, with the exhaust routed to the transom. Warm air ducts run behind panels and through interior lockers to cabin outlets. As the ducts pass through storage lockers, natural surface heat loss creates useful drying compartments for foul-weather gear — a welcome bonus in the damp Canadian maritime climate.
On a powerboat, the heater is normally installed in the engine compartment or machinery space, with hot air ducted to the cabins via flexible tubes. Diesel fuel can be drawn directly from the main tank using the included fuel metering pump. If your powerboat has a gasoline engine, a separate small diesel tank is recommended.
The heater operates within a permanent 15° angle and can start at up to 30° of heel. The exhaust hull fitting must be positioned a minimum of 300 mm above the waterline. Professional installation by a certified Eberspaecher marine dealer is strongly recommended.
Fuel Economy and Electrical Draw
The Airtronic D4 is remarkably frugal. Fuel consumption ranges from 0.11 litres per hour at the lowest setting to 0.51 litres per hour at full boost. This means a full day of moderate heating uses less than a few litres of diesel — a negligible draw on your main tank.
A 12-volt battery connection powers the ignition, fuel metering pump, and main air fan. Electrical consumption ranges from 7 watts at low output to 55 watts at boost. The system is designed to balance economical electrical draw with optimal heat and airflow performance, making it suitable for boats without shore power or generator access.
Quiet Operation and Air Quality
The Airtronic D4 exchanges heated air continuously through the cabin, reducing condensation and dampness — a persistent problem on boats in Canadian waters. Because combustion is sealed and exhausted externally, there are no fumes, no moisture by-products, and no oxygen depletion inside the cabin. The air you breathe stays fresh while the temperature stays comfortable.
Noise levels are kept low by the heater's internal design and the optional combustion air silencer. The fuel metering pump should be mounted on surfaces that won't transmit sound into accommodation areas.
Specifications
- Heat Output Range: 900 / 2,000 / 3,000 / 4,000 watts (3,400 / 6,800 / 10,200 / 13,650 BTU)
- Voltage: 12V or 24V DC
- Air Flow Volume: 55 / 100 / 140 / 175 m³/h
- Electrical Power Consumption: 7 / 16 / 30 / 55 watts
- Fuel Consumption: 0.11 / 0.25 / 0.38 / 0.51 litres/hour
- Fuel Type: Diesel (DIN EN 590)
- Heater Dimensions (L x W x H): 371 x 140 x 150 mm
- Heater Weight: 4.5 kg
- Suitable Sailboat Length: 26 to 36 feet
- Suitable Powerboat Length: 17 to 32 feet
- Ducting Included (Large): 3-1/2" x 30 feet
- Ducting Included (Small): 3" x 13 feet
- Copper Fuel Line Length: 25 feet
- Double-Wall Exhaust Tubing Length: 10 feet
- Maximum Duct Rating (90 mm ducting): 10
- Maximum Duct Rating (75 mm ducting): 3
- Maximum Operating Angle (permanent): 15°
- Maximum Starting Angle: 30°
- Minimum Exhaust Hull Fitting Height Above Waterline: 300 mm
- Warranty: 2 years / 2,000 hours (parts and labour)
Key Features
- Four selectable heat output levels — tailor cabin temperature from gentle background warmth to rapid full-cabin heating
- Complete installation kit — includes all ducting, exhaust, fuel lines, vents, and controller so nothing else needs to be sourced
- Digi-Controller with diagnostics — set desired temperature and monitor heater status from a convenient cabin-mounted panel
- Sealed combustion system — no fumes, moisture, or oxygen depletion inside the cabin for safe overnight use
- Extremely low fuel consumption — heat your cabin all day on less than a few litres of diesel from your main tank
- Compact form factor — fits in cockpit lockers and engine compartments where space is limited on cruising boats
- Continuous air exchange — reduces condensation and dampness that cause mould and mildew below decks
- Multi-cabin distribution — Y-pieces and closeable vents let you direct warm air where it's needed most
- Passive drying compartments — ducting routed through lockers provides gentle heat for drying foul-weather gear
- Operates on standard 12V DC — no generator or shore power required for independent heating at anchor or on the hook
- Proven reliability — over 30 years of successful marine installations worldwide in demanding offshore conditions
 Espar Marine Heating Brochure
Espar Airtronic Marine Installation Manual
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