If you are travelling off-grid and need reliable heating without relying on mains power, the Thermomate 12V 5kW Diesel Air Heater is built exactly for that purpose. Designed for caravans, camper trailers, vans, motorhomes and even boats, this unit runs on diesel fuel and a 12V power supply, making it a practical heating solution wherever you go.

This heater uses a high-efficiency aluminium heatsink design combined with automatic temperature control to deliver consistent and fast heat. It is based on a proven European-style system and is designed to warm enclosed spaces quickly while maintaining fuel efficiency. :contentReference[oaicite:1]{index=1}
Table of Contents
- Why this heater is worth considering
- Main features
- Key specifications
- Who it suits
- Important points before you buy
- What is in the box
- FAQs
Why this heater is worth considering
The Thermomate diesel heater is designed as a self-contained heating system for mobile environments. Unlike electric heaters, it does not require 240V power, and unlike LPG heaters, it offers efficient fuel consumption and long run times.
With a 5kW output, it is capable of heating most caravan and van interiors quickly. The heater distributes warm air through ducting, ensuring the entire space becomes comfortable rather than just heating one area.
Another key benefit is convenience. The system includes an LCD control panel and remote control, allowing you to adjust temperature, set timers, and control the heater without leaving your bed or seat. :contentReference[oaicite:2]{index=2}
Main features
- Powerful 5kW heating output
- 12V operation for off-grid use
- Diesel fuel system with high efficiency
- LCD control panel and remote control
- Automatic temperature control
- Fast heat-up with aluminium heatsink
- Quiet operation once running
- Auto cool-down cycle for safety
- Compact design for flexible installation
- Complete installation kit included
Key specifications
| Specification | Details |
|---|---|
| Brand | Thermomate |
| Model | TH-RVH5 |
| Power | 5kW |
| Voltage | 12V |
| Fuel type | Diesel |
| Fuel tank | 10L (up to approx. 36 hours runtime) |
| Fuel consumption | 0.21–0.51 L/hour |
| Noise level | Approx. 70–90 dB |
| Operating temperature | -40°C to +20°C |
| Remote range | Up to 30m |
| Weight | Approx. 7kg |
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Who it suits
This heater is ideal for:
- Caravan and camper trailer owners
- Van life setups and motorhomes
- Off-grid travellers
- Cold-weather camping
It is especially useful for overnight heating, keeping your space warm without running your vehicle engine.
Important points before you buy
This is not a plug-and-play product. Installation is required, including:
- Fuel line installation
- Exhaust routing
- 12V electrical connection
Proper installation is critical for safe operation. The heater also requires adequate airflow and ducting space.
Because this is a 5kW unit, it may be oversized for very small vans. Running it continuously at low output can lead to carbon build-up over time.
What is in the box
- Thermomate diesel air heater unit
- LCD control panel
- Remote control
- Wiring loom
- Ducting and vents
- Inlet air pipe
- Exhaust pipe and muffler
- Fuel pump and mounting kit
- Fuel hose and connectors
- Mounting hardware
- User manual
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Final thoughts
The Thermomate 12V 5kW Diesel Heater is a high-value off-grid heating solution that delivers strong performance for caravans and mobile setups. It heats quickly, runs efficiently, and comes as a complete kit.
While installation is required, once set up it provides reliable, low-cost heating that is hard to beat for travel and camping use.
Frequently Asked Questions
Does this heater need mains power?
No. It runs on diesel and a 12V battery system.
How long can it run on a full tank?
Up to approximately 36 hours depending on heat settings. :contentReference[oaicite:5]{index=5}
Is it noisy?
It is louder during startup but becomes quieter once it reaches operating temperature.
Can I install it myself?
Yes, if you are comfortable with mechanical and electrical installation.
Is it suitable for small vans?
It may be too powerful for very small spaces. A lower output heater could be more suitable.