This Diesel air heater 8KW from Hcalory (model HBU-3) runs on 12V or 24V DC. It draws diesel from a separate 15L external tank. The aluminium body gives an 18% boost in heating efficiency. It heats spaces up to 25m² and reaches 50°C in 3 minutes.
You can control it three ways: a remote, an LCD panel or the Hcalory app. The app sets timers and the temperature differential. There are 10 power gears and an automatic start-stop thermostat.
Fuel use is 0.11-0.36 L/h. That gives up to 136 hours of running in optimal conditions. A 5-level altitude mode covers 1,000m to 5,000m. Overheat protection applies at 270°C or above.
The listing markets it as 8KW. Some owners doubt this. One measured it as about 4.5kW and another thought it matched the size of their old 5KW unit. Another owner called 8KW a "beefier 5KW" and was happy with the output. Judge it by the 25m² heating area rating and the 10 power gears. A shed, van or cabin is the sort of space it is rated for.
HCALORY rates it for spaces up to 25m². The listing names cars, RVs, boats, trucks, camper vans, garages, log cabins, marine cabins and sheds as uses. Owners report using it in a 6.5m Sprinter van, a 28ft motorhome, a boat, a brick barn and a 15 x 10 foot shed. Insulation and draughts make a big difference to how warm a space gets.
Fuel use is 0.11-0.36 L/h. The comparison table gives 0.11-0.35 L/h. The external tank holds 15L. HCALORY quotes up to 136 hours of continuous running under optimal conditions. In practice higher gears burn more. One owner reported using about 10 litres of diesel in their first period of use.
Yes. It comes with a remote control and an LCD digital switch. The Bluetooth app (search "Hcalory") adds timers, plateau mode, fan mode and an adjustable temperature differential. The app also has language and unit switching. One reviewer said the app made it friendlier than older non-Bluetooth versions. They also said the timer was easy to set.
Yes. The system automatically adjusts the air-fuel ratio in thin air. The bullet points say 5 levels from 1,000m to 5,000m. The product description says dual modes of 2,500m and 5,000m. These two statements do not match. HCALORY says output at 5,000m (16,400 ft) matches sea level. Ask the seller which version you will receive.
It has short circuit, reverse connection, over-voltage and over-heat protection. Over-heat protection triggers at 270°C or above (518°F). The heater must exhaust to the outdoors to prevent carbon monoxide poisoning. Point the exhaust away from the air intake and downwind. Check the overnight wind forecast because a change can blow fumes back or cause a flameout. Wrap the hot exhaust where it passes near anything flammable.
Reviewers mostly found it easy. One called it self-explanatory and another said it was fiddly but doable. The kit includes the heater, LCD switch, remote, exhaust pipe and harness. For vehicle installs some owners suggest upgrading the fuel line, fuel filter and exhaust baffle or silencer. The fuel pump should sit at an angle rather than horizontal. The tank is external so you can place it where it suits you. The first start may take a few attempts while fuel reaches the pump. One owner's unit fired on the third try.
The HBU-3 has the largest tank in the range at 15L. The HC1-U2 has 10L. The HBH-3, HBH-3S and HBS-3 have 5L. The HBS-3S has 3.5L. The HBU-3 and HC1-U2 run on 12V/24V DC only. The other models also run on 220-240V AC. The HBH-3S and HBS-3S have a silent pump. The HBU-3 has the standard pump. One owner found the pump a little noisy on its lowest setting. All six models have Bluetooth app control, auto start-stop, a timer and thermostat mode. HCALORY lists the product again as Diesel air heater 8KW on the page.
The HCALORY HBU-3 is a 12V/24V DC diesel air heater with a separate 15L fuel tank. It is sold as an 8KW unit. The body is aluminium and was upgraded in 2026. HCALORY says this gives an 18% boost in heating efficiency. It is rated to warm spaces up to 25m² and to reach 50°C in 3 minutes.
Fuel use is 0.11-0.36 L/h. HCALORY's comparison table gives 0.11-0.35 L/h. With the 15L tank the heater can run for up to 136 hours without stopping under optimal conditions. The tank is external, so you can fit it away from the heater. One owner swapped from freestanding heaters with built-in tanks because this layout takes up less room.
There are three ways to control it: a remote control, an LCD panel switch and a Bluetooth app. The app is called Hcalory. It has a timer, plateau mode, temperature adjustment, fan mode, language and unit switches and a help section. You can also adjust the temperature differential in the app. The heater has 10 temperature settings and 10 power gears. In thermostat mode it switches itself on and off as the ambient temperature changes. HCALORY says this cuts fuel use and prevents overheating.
The listing describes a 5-level high-altitude mode for 1,000m to 5,000m. The product description instead mentions a dual mode at 2,500m and 5,000m (16,400 ft). The heater detects and adjusts the air-fuel ratio itself. HCALORY says output at 5,000m matches output at sea level. The pump is the standard type rather than the silent type used on the HBH-3S and HBS-3S.
The 2026 motherboard has short circuit protection and reverse connection protection. It also has over-voltage protection and over-heat protection at ≥270 °C. The heater must be exhausted outdoors to prevent carbon monoxide poisoning. It suits cars and vans. It also suits RVs and camper vans. Other uses are trucks and boats. Marine cabins and garages are also suitable. So are log cabins and other enclosed spaces.
The HBU-3 has the largest tank in the range at 15L. The HC1-U2 has 10L. The HBH-3 and HBH-3S have 5L and the HBS-3S has 3.5L. The HBH-3S and HBS-3S also run on 220-240V AC as well as 12V/24V DC. All six models have Bluetooth control and auto start-stop. They also have a timer and thermostatic mode.
| Brand | HCALORY |
| Model | HBU-3 |
| Manufacturer part number | HBU-3 |
| Colour option | Blue and red |
| Rated heating power | 8KW |
| Voltage | 12V/24V DC |
| Fuel type | Diesel |
| Fuel tank capacity | 15L (external tank) |
| Fuel consumption | 0.11-0.36 L/h |
| Maximum continuous run time | 136 hours under optimal conditions |
| Heating area | Up to 25m² |
| Time to reach 50°C | 3 minutes |
| Heating efficiency boost | 18% |
| Body material | Aluminium (2026 upgrade) |
| Temperature settings | 10 |
| Power gears | 10 |
| Altitude mode | 5 levels from 1,000m to 5,000m |
| Pump type | Standard |
| Control methods | Remote control, LCD panel and Bluetooth app |
| App functions | Timer, plateau mode, temperature adjustment, fan mode, language switch, unit switch, adjustable temperature differential |
| Auto start-stop | Yes |
| Thermostatic mode | Yes |
| Timer function | Yes (multi-group timer) |
| Motherboard | 2026 upgraded version |
| Protections | Short circuit, reverse connection, over-voltage and over-heat (≥270 °C) |
| Exhaust | Must vent outdoors |
| Suitable for | Cars, vans, camper vans, RVs, trucks, boats, marine cabins, garages, log cabins, camping |
| Package dimensions | 48 x 44 x 27 cm |
| Weight | 6.5kg |
| In the box | 1 x heater, 1 x LCD digital switch, 1 x remote control, 1 x exhaust pipe, 1 x harness |
