Spheros Thermo Plus 300 30kW Diesel heater 24V

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The Spheros / Valeo Thermo Plus 300 coolant heater

The Spheros / Valeo Thermo Plus 300 coolant heater is a powerful modern solution for heating large vehicles. With over 100,000 BTU of heating power, this heater is sure to keep your hydraulic equipment up and running even in the coldest environments. Powerful and efficient, the Thermo 300 is ideal for heating and maintaining trucks, buses, and construction vehicles. 

User Benefits of the 30KW diesel heater

  • Pre-heating high-power engines improves life expectancy and readiness for operation of the engine.

  • Brushless EC motor - extended running times
  • Quickly heat up passenger areas in busses without the engine running.

  • Maintain comfortable interior temperature at extreme colds on large vehicles with no/poor thermal insulation (construction machinery, large military vehicles, trucks).

  • The Spheros 30KW water heater quickly and efficiently heats up coolant and hydraulic liquid, for smooth and comfortable operation.

  • Less starting noises 

Keep your systems running smoothly in the harshest conditions

Preheating your engine with the Spheros Thermo Plus 300 forced flow coolant heater is easy and effective. The heater works by first heating up either the coolant or hydraulic fluid, and then pushing it through the cycle with an electric pump. This spreads the heat evenly throughout the cycle, ensuring smooth functionality of the entire system.

Preheating a large diesel engine is necessary when working in extreme temperatures, as without it the engine might not start at all. Not only does preheating ensure that the engine will start, it also reduces fuel consumption, engine wear, and emissions.

The Webasto/Spheros Thermo Plus 300 has a massive 102,000 BTU heat output. Thanks to an upgraded ECU, combustion chamber, and new sensors, the Thermo Plus 300 has minimal fuel and energy consumption. This makes it an economical, reliable, long-term solution to counter freezing climates.

The Spheros Thermo Plus 300 coolant heater is world renowned for its reliability, efficiency, and power. Installed in over 150,000 vehicles worldwide, Spheros heating systems are the leading coolant heating solution.

Key Features of the Spheros Thermo Plus 300

  • Includes all the necessary components for a straightforward installation, with installation instructions.

  • Supplies 102 400 BTU of heat for preheating the engine, warming up the cabin, and potentially supplying hot water.

  • Minimal fuel and power consumption makes the Thermo 300 economical, long-lasting, and ecological.

  • Advanced Diagnostic System accurately and reliably reports possible errors.

Included in the kit

  • Water pump

  • Switcher

  • Fuel filter

Spheros Thermo 300 Technical Specifications

Part Number


Voltage (V)


Fuel Type


Maximum Heat Flow (BTU (KW))

102 400 BTU (30KW)

Fuel Consumption (gallon/hour (liter/hour))

0.95 gal/h (3.6 L/h)

Power Consumption (W)

90 W without coolant pump

Dimensions (L x W x H)

540 x 250 x 222 mm

Weight (lbs (kg))

35 lbs (16kg)


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

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.