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Espar / Eberspacher Airtronic D4L 12v (4kW) Heater Kit

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  • Espar / Eberspacher EasyStart Pro Timer 221000352200

The Espar D4L 12V heater


This powerful Espar diesel heater offers reliability, cost effectiveness and versatility in terms of installation. It can operate at high altitudes (up to 9,900 feet / 3,000 m) with automatic altitude adjustment as standard, which means no additional high altitude kit is required. It heats up vehicles quickly, quietly and efficiently, and its power (up to 4kW / 13650 BTU of heating output) and ducting options make it ideal for larger, multi-cabin vehicles. DIY installation is possible, and the unit is easy to use, with thermostatic function, timer and highly accurate on-screen fault diagnostics.

Key features of the Espar Airtronic D4L diesel heater kit

  • Reasonably priced and offering impressive heat output of up to 4kW / 13650 BTU, this Espar heater is available in 12V and 24V options.
  • The Espar D4L is built for tough conditions, and works in temperatures down to - 46 / - 50 F.
  • It can also handle high altitudes. When equipped with the EasyStart Pro controller, which offers automatic altitude adjustment, this heater can operate at up to 9,900 feet / 3,000 m. No additional wiring or installation is required for high altitude use.
  • This Espar heater features an integrated temperature sensor for thermostatic functionality, and is simple and easy to control when used with the EasyStart Pro controller (which we recommend for this model).
  • The Espar D4L diesel heater also boasts a timer function so you can set heating times.
  • Another benefit is quieter performance. There is reduced clicking noise compared to previous models thanks to the D4L’s new stepless blower system.
  • Additionally, the brushless fan is quieter than previous models, further reducing overall noise output.
  • The Espar Airtronic D4L diesel heater kit offers a range of installation possibilities. You can have up to 4 ducting outlets, and outlet diameter can be either 60mm, 75mm or 90mm.
  • The ducting system supports up to 15 meters / 49 ft of ducting, making the Espar Airtronic D4L well-suited to larger, multi-cabin vehicles or mobile homes. If you need a different length or outlet combination for your ducting, the Espar D4R model might be a suitable alternative.
  • DIY installation is possible. The plug and play installation kit requires fewer tools than previous models and no cable crimping.
  • Installing the fuel system is also simpler than with previous models. The same line is used for the whole installation.
  • The Espar Airtronic D4L diesel heater kit uses CAN, LIN and S+ communication protocol technologies. This makes it compatible with earlier generation controllers.
  • The new controller communication system on the Espar D4L offers improved accuracy for on-screen fault diagnostics.
  • This Espar diesel heater has a longer operating life than previous models (up to 5,000 hours compared to 3,000 previously) thanks to its brushless fan. 
  • Accessories and parts from previous D4 models can be used with the Airtronic D4L.
  • Custom kits are available in order to fit the Espar Airtronic D4L diesel heater to any vehicle or marine application. This means it can operate as an Espar marine heater. Contact the Heatso team with your requirements and we can put together a custom kit, calculate the ducting rates, suggest outlet options and plan the layout (for marine applications).

User benefits of the Espar Airtronic D4L diesel heater kit

Ideally suited to larger, multi-cabin vehicles, boats and motorhomes, the Espar D4L offers a cost effective long term heating solution. Its improved combustion operation means it is greener than previous models, and it offers good fuel economy.

This is also a versatile heating kit. You can install it yourself thanks to plug and play installation, and its range of different ducting options makes it suitable for a wide range of vehicle types and applications. The D4L offers double the power of the Espar D2L and also has much longer routing capability. Smaller than the D5 unit, this is a heater that still packs a punch and can offer powerful heating where space is a challenge (although please note it can be awkward to install under the passenger seat in vans).

The Espar Airtronic D4L diesel heater kit’s ability to handle tough conditions is also a plus. This is a reliable heater from a reputable German manufacturer that is engineered to last.

You can pair this heater with the EasyStart Pro controller for use in high altitudes, and head out in winter confident that your vehicle will stay heated. 

Who the Espar Airtronic D4L diesel heater kit is suitable for

Powerful and robust, this diesel heater is ideal for larger motorhomes. It is suitable for a large range of vehicles:

  • Trucks
  • Vans
  • Campervans / motorhomes
  • Caravans
  • Horse Boxes
  • Mobile Workshops
  • Boats (requires marine kit)

Heatso’s engineers are here to help

The Espar D4L is an excellent heating option for your vehicle. But if you have any questions about it, or would like to hear about other options, our customer service is onhand to help. And when you do find the ideal solution to meet your needs, our engineers are available to talk you through the whole installation process, step by step.

Technical specifications:



Diesel – EN 590

Heat Flow Control





Heat Flow










Fuel Consumption

l / h





gal/ h




Average Power consumption





Average Power Consumption while Starting



Rate Voltage


12 volt

Dimensions LxWxH


371 x 140 x 150


  • Eberspacher Airtronic D4L 12v Heater
  • Fuel pump (12v)
  • Fuel hose
  • Exhaust Silencer
  • Electrical harnesses
  • Stainless steel exhaust pipe - approx. 90cm
  • Combustion intake pipe 
  • Flexible ducting - 0.5 meter
  • Inlet / Outlet grills
  • Air outlet (90mm)
  • Screws, clips and plastic straps required for installation
  • Installation manual
  • Warranty documentation 

Eberspacher / Espar Part Number:

  • 25.2720.05.0000 /  25.2720.05.0000 / 252720050000 (Heater)
  • 25 2720 80 0000 / 25 2720 80 00 00 / 252720800000 (Installation kit)

Shipping Times:

  • United States - 1 Working Day
  • United Kingdom - 1 Working Day
  • Western Europe - 2-3 Working Days
  • Eastern Europe - 3-5 Working Days
  • Scandinavian Countries - 2-3 Working Days
  • Australia / New Zealand - 2-3 Working Days
  • Rest of World - 2-4 Working Days

If you want to use this heater in a boat, you will need a marine installation kit. You can add it to your order at the bottom of this page. Please click here to see what is included in the marine installation kit.


Installation, servicing and maintenance must be done in accordance with manufacturer’s guidelines. Failure to follow these guidelines will result in voiding your warranty. 

We provide free technical and installation support via email or phone to all of our customers who purchase a heater, heater kit or other products from Heatso. We take pride in our customer service and want to ensure that your heater system is properly installed. As a result, if you have any difficulties, please do not hesitate to contact us at [email protected].

If you require removing and/or refitting your item, please visit a local professional or authorised specialist, if you can not find one you can contact us and we will try to recommend a local partner to assist with the task. The cost of removing and/or refitting this item is not covered by the warranty.

Standard/Premium Warranty Terms for Espar/Eberspacher or Webasto Heaters & Heater kits

2 Years + optional 1 year extended Warranty available

If the item has failed within warrantable conditions:

  1. Please fill out the contact form on the “Contact us” page.
  2. A representative will contact you within 24 business hours to confirm the details and assist you further.
  3. If the product needs to be inspected by our service engineer, we will provide shipping labels for you to print and attach before handing over to our courier for collection.
  4. The shipping label will contain instructions for arranging pickup at your location or drop off at a nearby FedEx location. Follow these instructions to pass the package to FedEx.
    1. *The Label must be attached to the packages before leaving the package with FedEx.
    2. *You can also choose to drop off the item at a FedEx post office instead of requesting a courier collection.
    3. *If after inspection it appears that the item is not warrantable and the malfunction is caused by a non-warrantable condition, we will kindly ask you to cover shipping expenses at a discounted flat rate.
  5. On average, diagnostics of heaters and their parts takes 3 to 4 working days from the moment the item has reached our warehouse.
    1. *The diagnostics report is provided by a manufacturer approved authorised service centre.
  6. If during diagnostics it was concluded that the fault falls under non-warrantable conditions, our customer support will reach out to you and provide you with an estimated repair cost.
    1. *Please note that we strive to provide the lowest possible repair prices.
  7. Under normal circumstances it can take 3-7 working days after diagnostics to repair most minor malfunctions.
    1. *Please note that each case is unique and your repairs may take longer depending on the fault.


*Please note that all deadlines above are approximate and everything depends on the specific details of each case.

**If your item has been installed by a third party, please save all the documentation.This documentation can help find and fix the fault faster.

2 Reviews Hide Reviews Show Reviews

  • 5
    Airtronic D4L

    Posted by Phil K on 26th May 2020

    I replaced a Chinese knockoff that died in one season. I could not find parts to repair it, so I splurged and bought this one for our 34&quot; RV. It heats way better than the 8kw knockoff we had. It is also quieter. All of the componants are much better quality. I wish I had not cheaped out the first time

  • 5

    Posted by Henrik on 17th Dec 2019

    Small but powerful enough to heat our long wheel base Sprinter and I think this is more than enough. I guess that smaller heater would be enough but I was worried because there is no insulation and we sometimes have to keep our guard dogs inside during the cold nights so this burner makes sure the my four legged partners are comfortable when on duty.