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Espar / Eberspacher Hydronic D4E 12V Diesel RV Kit - 4.3KW- CS Version

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An upgraded version of the popular D5S Hydronic kit, the new Espar Hydronic D4E RV kit was designed with optimal performance and the highest quality standards in mind. A proven heater on the market from one of the most reputable and reliable German manufacturers, this model comes with a brushless fan, a quieter pump and an integrated temperature and altitude sensor. The heater, known as the Eberspacher Hydronic D4E in Europe, uses your vehicle’s own fuel to heat air, water and even floors. Typically bundled with the modern EasyStart Pro controller, this kit can be connected to a variety of water and air exchangers. The kit comes with all the parts needed for installation, including mounting brackets, clamps and screws. We can also offer you a custom build – get in touch today to learn more.

This is a CS version  -m allows Pro controller connection and operation in high altitudes. CL versions are cheaper, but they can only operate up to 5K feet

Key features of the Espar Hydronic D4E 12V RV kit

  • As a third-generation hydronic heater of the CS variety, the D4E is much more versatile than its predecessors and is being constantly updated.
  • Due to its compact size, the heater can be fitted either in the vehicle engine compartment or internally.
  • The maximum heat output of this model is 4.3kW / 14,663 BTU. 
  • The kit ships together with an 4.3 kW Kalori air heater, which is mounted internally. The Kalori unit can be connected to different areas via ducting adapters.
  • The kit includes a water plate exchanger for heating water that connects to the tap or shower and is mounted internally.
  • The Espar Hydronic D4E can be operated independently or connected to the vehicle’s own engine coolant system.
  • When used together with the EasyStart Pro controller, the kit can operate at altitudes as high as 3,000 meters / 9,900 feet. Without the controller, the maximal operational altitude is still relatively high at 1,500 meters / 4,900 feet.
  • The kit is equipped with a brushless motor resulting in quieter output and higher comfort levels.
  • The brushless motor also means the lifecycle is increased from 3,000 to 5,000 hours.
  • Thanks to the heater’s stepless system, fan speed is adjusted according to the temperature set. This maximizes efficiency and improves comfort. 
  • An improved fuel pump piston provides the additional benefit of reducing the clicking sound, which can be rather annoying in other models.
  • The EasyStart controller provides an automatic temperature control option (Thermostatic function) due to its integrated temperature sensor.
  • The unit works with both CAN and S++ communication protocols.

User benefits of the Espar Hydronic D4E 12V RV kit

This diesel heater RV kit can be used for a variety of purposes, including heating up water, air, car floors, radiators and the engine. Unlike some other diesel RV heaters, this unit is extremely easy to install, in part due to its compact size. Due to several features including a brushless motor, the model is quieter and does not interfere with your sleep, a problem users of older units commonly face.

One way to save both power and fuel is using residual heating with a switched-off engine. This feature allows the system to run for as long as the coolant temperature does not drop below the threshold set by the user. The kit can operate with different water and air heat exchangers. It can also run an independent heating loop with multiple accessories connected to it.

The shipped kit provides a complete domestic water heating system that can be used for showers and taps. In addition, the universal kit can be used to pre-heat the engine, as well as heat air and floors. If you require extra features, custom kits can be built on demand. Contact us for more information.

Who the Espar Hydronic D4E 12V RV kit is suitable for:

The Espar Hydronic D4E 12V RV kit is a popular choice for many Recreational Vehicle enthusiasts. This versatile unit will provide a comfortable heating experience with:

  • Vans and converted vans (Mercedes, Freightliner, Dodge Sprinter, Fiat Ducato, Ram Promaster, Ford Transit, Nissan NV, VW Crafter)
  • RVs, caravans, campervans and motorhomes
  • Military / Army / Defense vehicles
  • Passenger vehicles, including buses, coaches and school buses
  • Boats, narrowboats and other vessels (marine kit required)
  • Other applications, including mobile workshops

Heatso’s engineers are here to help

The Espar S3 D4E 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 or 24volt

Allowed operating pressure


Up to 2.5 bar

Minimum water flow rate

L / hour



gal / hour


Dimensions LxWxH


215 x 91 x 144

*20 percent mixture with FAME is permitted – EN 14214


Water pump:

Water Pump power consumption

Approx. 12 watts

Delivery Rate

Approx. 500 liter per hour

132 gallon per hour

Delivery Pressure

0.2 bar





Espar / Eberspacher D4E Hydronic 3 12V 4.3kW kit includes:

• Diesel Eberspacher / Espar Hydronic 3 D4E Heater 12V and EasyStart PRO controller
• Kalori Blower controller unit
• All electrical harnesses and connections
• 1 meter of exhaust pipe
• 1 meter of combustion Intake pipe 
• 2.3m of water hose (Heater) (20mm)
• 4m of water hose 16mm ID (Blower Box)
• 1 Exhaust Silencer (24mm)
Circulating Water Pump (for glycol / coolant circulation in Hydronic system ) 
• Fuel Pump
• All necessary clips and screws
• Heater water (expansion) tank 5 Liter 
• Espar / Kalori Blower box 4.3kw with Grill - air blower unit water plate exchanger
• Hydronic Mounting Bracket


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.

1 Review Hide Reviews Show Reviews

  • 5
    Thank you

    Posted by Neil on 28th Jun 2021

    I will take credit for this kit. Thank you heatso team for composing 14k BTU for me. I think more people will be interested in 14k instead of 17k