Espar Airtronic M3 D4L Diesel 12V Marine Heater kit with EasyStart Pro Controller

Marine diesel heater for quiet, dry cabin warmth on every crossing

Stay comfortable and condensation-free with steady, fuel-sipping heat built for open water. The Espar Airtronic M3 D4L 12V delivers up to 13,600 BTU (4.0 kW) and pairs with the EasyStart Pro controller for precise temperature control and scheduling.

Benefits & Use Cases

This compact Espar marine heater warms cabins fast while keeping humidity down—ideal for overnighting, shoulder-season cruising, and protecting electronics from damp air. Designed for reliable starts and smooth output in changing conditions, it’s a great fit for coastal hops and extended passagemaking alike.

• Fast, even heat with high airflow for multi-cabin boats
• Dry, comfortable interior—reduces condensation and odors
• 12V diesel operation for efficient, independent heating underway or at anchor
• EasyStart Pro: set-and-forget timers, diagnostics, and fine temperature control

Technical

• Fuel: Diesel
• Voltage: 12V
• Heat Output: 13,600 BTU / 4.0 kW
• Max Operating Altitude: 5,500 m (18,000 ft)
• Warranty: 2 years
• Dimensions (heater body): 376 × 140 × 150 mm (14.8 × 5.5 × 5.9 in)

Part numbers:

• Complete kit: 202829550402 + Marine kit accessories
• Heater only: 252955050000
• Alternative formats: 20.2829.55.0402; 20.2829.55.04.02; 20 2829 55 0402 ; 20 2829 55 04 02

Browse Eberspächer/Espar Manuals & Technical Documentation

Vehicle Compatibility

• Motor yachts: ~19–29 ft
• Sailing yachts: ~26–36 ft

Kit Includes

• Espar Airtronic M3 D4L Diesel 12V heater
• Fuel metering pump (12v)
• EasyStart Pro Controller
• Additionally included: Pro controller extension included 9.8 ft/ 3m
• Marine Grade Fuel line - ISO7840 - 19.7 ft / 6 m
• Fuel tank standpipe
• Air Intake Silencer / Muffler
• Electrical harnesses - Plug n' Play
• Marine Grade exhaust system with silencer - approx. 6.6 ft / 2m!
• L-shaped exhaust adapter with a drain for condensation drip
• Aluminum sheet for floor protection
• Hull skin fitting
• Combustion intake pipe ~3.3ft / 1 meter
• Inlet / Outlet grills
• Additionally included: L-shaped marine grade mounting bracket
• Air outlet grill (90 mm. diameter)
• Screws, clips, and plastic straps are required for installation
• Installation manual CD (Scan QR code for installation manual download)

2 outlet options will have additionally:

• 2 meters of 75mm hot air tubing
• 3 meters of 90mm hot air tubing
• 1 x 90mm "Y" tube branch connection
• 1 x 75mm to 90mm hot air tube reducer
• 1 x 75mm hot air outlet
• 1 x 90mm hot air outlet