Espar Airtronic M3 D4R Diesel 12V Marine Heater Kit with EasyStart Pro Controller

12V diesel marine heater for reliable onboard warmth

Built for cold-weather comfort on the water, this 12V diesel marine heater delivers steady cabin warmth for motor yachts and sailing yachts. With 13,650 BTU (4.0 kW) output, diesel operation, and the EasyStart Pro controller, the Espar Airtronic D4R marine kit is designed for dependable heating in demanding marine conditions.

Benefits & Use Cases

This Espar marine heater kit is built for boat owners who need reliable warmth during early starts, overnight stays, shoulder-season cruising, and cold marina stops. Its strong air throughput supports longer ducting layouts, making it a practical choice for marine cabins that need even heat distribution.

The included marine-grade exhaust system, fuel line, hull fitting, controller, and mounting hardware help support a clean installation for yachts, sailboats, and marine cabins.

• Steady onboard comfort for cool-weather boating, overnight stays, and winter layups
• Strong 13,650 BTU (4.0 kW) heat output for mid-size marine cabins
• Flexible outlet options for marine kit only, 2 outlet system, or 3 outlet system layouts
• Low 5–42 W operating power draw for battery-conscious marine heating

Technical

• Fuel Type: Diesel
• Voltage: 12V
• Max Heat Output: 13,650 BTU (4.0 kW)
• Fuel Consumption: 0.03–0.135 gal/h (0.11–0.51 l/h)
• Power Consumption: 5–42 W; starting ≤100 W
• Max Altitude: 18,000 ft (5,500 m)
• Warranty: 2 years; optional Extended (+1 Year)
• Dimensions (Heater body only): 14.6 × 5.5 × 5.9 in (371 × 140 × 150 mm)
• Certifications: ECE R122 (heating) and ECE R10 (EMC)
• Controller: EasyStart Pro Controller
• Outlet Options: Marine kit only (no duct accessories), 2 Outlet system, or 3 Outlet system

Part numbers:

• Installation kit: 252720800000 + Marine kit accessories 
• Heater only: 252955050000
• Alternative formats: 25.2955.05.0000; 25.2955.05.00.00; 25 2955 05 0000; 25 2955 05 00 00

Browse Eberspächer/Espar Manuals & Technical Documentation

Compatibility

• Motor yachts: approximately 19–29 ft
• Sailing yachts: approximately 26–36 ft
• Marine cabins requiring diesel air heating and 12V electrical compatibility
• Longer ducting marine layouts where higher air throughput is required

Kit Includes

• Espar Airtronic M3 D4R 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

3 outlet options will have additionally:

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

FAQs

What boats is this Espar D4R marine heater kit suitable for?
This kit is suited for motor yachts around 19–29 ft and sailing yachts around 26–36 ft. Final fit depends on cabin layout, insulation, duct routing, and onboard power setup.

What is the difference between the marine kit only, 2 outlet, and 3 outlet options?
The marine kit only option does not include duct accessories. The 2 outlet and 3 outlet systems add hot air tubing, branch connections, reducers, and outlets for multi-zone cabin airflow.

Does this 12V diesel air heater include a controller?
Yes, this kit includes the EasyStart Pro Controller and a 9.8 ft / 3 m controller extension. This gives you practical onboard control for cabin heating. 

Can this Espar marine heater operate at high altitude?
The listed max altitude is 18,000 ft (5,500 m). For extended high-altitude use, correct installation, airflow, and fuel delivery are important. 

What fuel and power does this marine heater use?
This heater runs on diesel and uses 12V power. Operating power consumption is 5–42 W, with starting power draw up to 100 W.

Is installation hardware included?
Yes, the kit includes key marine installation components such as harnesses, fuel line, exhaust system with silencer, hull skin fitting, mounting bracket, and required clips, screws, and straps.