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The Autoterm Flow 5D 12V diesel hydronic heater is a compact 5kW coolant heater for vehicle engine pre-heating and small closed-loop heating systems in motorhomes, campervans, commercial vehicles and suitable marine installations.
This is a hydronic heater. It heats coolant, not cabin air or drinking water directly. Cabin heating needs a compatible fan matrix or radiator. Domestic hot water needs a correctly designed calorifier or heat exchanger. These system components and professional installation should be allowed for when planning your project.
Is the Flow 5D right for your system?
- Electrical system: 12V DC
- Fuel: diesel meeting EN590
- Heat output: 5kW
- Heating medium: compatible coolant or antifreeze coolant in a closed loop
- Best suited to: engine pre-heating for vehicles up to approximately 4 litres, plus small hydronic radiator, fan-matrix or boiler circuits
- Coolant circuit: Autoterm specifies an optimal volume of 10–12L and describes applications up to 30L; larger or more complex circuits need installer confirmation
How it works
The Flow 5D burns diesel in a sealed combustion chamber and transfers the heat into the vehicle or heating-system coolant. A circulation pump moves the heated coolant through the loop. Depending on the completed system, that heat can pre-warm an engine, feed a cabin fan matrix or radiator, or transfer energy through a suitable boiler or calorifier heat exchanger.
No warm-air duct connects directly to the Flow 5D. If your goal is cabin heating, choose a compatible hydronic fan matrix or radiator and have the full loop sized together.
Technical specifications
| Model | Autoterm Flow 5D diesel |
|---|---|
| Rated voltage | 12V DC |
| Heating output | 5kW |
| Running electrical consumption | 42W |
| Start-up electrical consumption | 122W |
| Maximum fuel consumption | 0.62L/h |
| Coolant flow at 0 bar | 1,200L/h |
| Coolant flow at 0.18 bar | 800L/h |
| Coolant connections | 18mm outside diameter |
| Maximum working altitude | 1,000m above sea level |
| Heater dimensions | 220 × 90 × 136mm |
| Heater weight | 2.4kg |
| Manufacturer set weight | 8kg |
Package and controller check
The supplier gallery shows the heater with installation components, coolant pump, fuel and exhaust parts, wiring and a system diagram. However, the supplier listing does not publish a definitive item-by-item box list or identify the included control panel.
Autoterm states that a compatible control panel is required for operation and lists Comfort Control, Push Control and Touch Control as compatible choices. Please ask us to confirm the current package contents and controller before ordering, especially if you are matching an existing installation.
Installation notes
This product needs specialist hydronic, diesel-fuel, exhaust and 12V electrical installation. The heater must sit below the coolant expansion tank, the circulation pump must be positioned correctly in the loop, and the system must be fully bled before first use. Trapped air can cause overheating.
Autoterm also requires the combustion-air supply to come from outside or a well-ventilated area, secure leak-free coolant connections, suitable exhaust routing and protection from water, road spray, heat and contamination. The heater must not be installed in a coolant system that can exceed 2.1 bar.
Frequently asked questions
Does the Flow 5D blow warm air into my motorhome?
Not by itself. It heats coolant. Add a suitable fan matrix or radiator to transfer that heat into the living area. Browse our RV heating accessories or ask us to help plan the components.
Can it make domestic hot water?
It can supply heat to a correctly designed boiler, calorifier or heat-exchanger circuit. It must not be connected directly to potable water. Your installer should design the coolant and domestic-water separation.
Is a controller included?
The current supplier page does not identify the included controller. A compatible Autoterm control panel is required, so confirm the package configuration with us before ordering.
Can I use this 12V model in a 24V vehicle?
Not directly. This listing is the 12V diesel version. Match the heater voltage to the installation and use the correct Autoterm wiring and pump configuration.
Can it be fitted into an existing engine cooling system?
Often, but the coolant direction, hose size, expansion tank, system pressure, vehicle electronics and cabin-heater controls must all be checked. Some newer vehicles may need additional control hardware.
Can Select Caravans help with suitability?
Yes. Our Auckland team can help you confirm the intended use, voltage, coolant-loop size and supporting components before purchase. We deliver RV accessories throughout Auckland and across New Zealand.
