A diesel or kerosene space heater can provide a high heat output for temporary industrial heating. Choosing one starts with the working environment: check that a direct-fired heater is suitable before comparing power, fuel use and portability.
This guide compares three Hyundai models — HY70DKH, HY125DKH and HY215DKH — and explains what to check before you buy.
Before you buy: these are direct-fired, unflued heaters. Combustion gases enter the heated space. They are not domestic room heaters and must never be used in living or sleeping areas, confined spaces or poorly ventilated areas. Do not assume that opening a garage door makes an installation suitable. Check the model manual and ask our team if your proposed location is suitable.
Compare the Hyundai diesel heater range
All three models use diesel or kerosene, have thermostat control and require a 230V electrical supply. Their heat outputs are shown in kilowatts (kW) and British Thermal Units per hour (BTU/hr).
On a phone, swipe across the table to compare all three models.
| Specification | HY70DKH | HY125DKH | HY215DKH |
|---|---|---|---|
| Heat output | 20kW / 70,000 BTU/hr | 37kW / 125,000 BTU/hr | 63kW / 215,000 BTU/hr |
| Approx. heating volume* | 496m³ | 900m³ | 1,500m³ |
| Fuel tank | 19 litres | 38 litres | 50 litres |
| Listed fuel consumption | 1.9 litres/hour | 3.6 litres/hour | 5.8 litres/hour |
| Approx. run time per tank* | 10 hours | 10.5 hours | 8.5 hours |
| Portability | Carry handle; no wheels | Wheels and handle | Wheels and handle |
*Heating volumes and run times are approximate product-page figures, not a guarantee for a particular building. Insulation, ventilation, outdoor temperature and thermostat cycling affect results. Heating volume is measured in cubic metres (m³), not square metres (m²).
1. Check the space before choosing the output
Measure the length, width and height of the space. Multiplying these gives its volume in cubic metres. For example, a space measuring 10m × 6m × 3m has a volume of 180m³.
Volume alone does not tell you which heater to buy. A high roof, poor insulation, open doors and the ventilation required for safe operation all affect heat loss. Tell our team the dimensions, building type, ventilation arrangements and temperature you want to reach. Do not simply buy the largest model or reduce ventilation to retain heat.
- HY70DKH: the lowest-output option in this comparison, with a carry handle for moving the cooled heater.
- HY125DKH: a step up to 37kW, with wheels and a larger fuel tank.
- HY215DKH: the highest output here at 63kW, with higher fuel consumption and a 50-litre tank.
For an enclosed workplace, ask about an appropriately specified electric or indirect-fired heating system instead. Do not treat a general workshop or warehouse description as approval to use a direct-fired heater indoors.
2. Compare fuel use, not just tank size
A bigger tank does not automatically mean a longer run time: a higher-output heater also burns more fuel. Compare the listed litres per hour alongside tank capacity and the length of your working day.
To estimate the fuel cost while the burner is running, multiply litres per hour by your fuel price per litre. Electricity use and thermostat cycling also affect the total operating cost.
Use only the fuel grades approved in the model manual. Both diesel and kerosene are listed for these heaters, but petrol, solvents, waste oil and unapproved mixtures must not be used. Buy fresh fuel and store it in suitable, clearly labelled containers.
3. Plan for power, controls and moving the heater
Diesel provides the heat, but these models still need a 230V electrical supply for their powered components. They are not fuel-only heaters for sites without electricity. Check the rating plate, manual and suitable electrical protection before use.
The thermostat switches the heater off when the set temperature is reached and allows it to restart as the temperature falls. It is not a substitute for correct sizing or ventilation, and the heater may restart automatically while switched on.
Think about doorways, steps and storage as well as wheels. Never move or handle a heater while it is running or hot. Follow the manual's instructions for cooling, fuel removal and transport.
4. Make safe operation part of the buying decision
- Read the exact model manual. Confirm the permitted location, fresh-air requirements and clearances before use. If instructions are unclear or conflict with a product description, ask Hyundai support before operating.
- Keep the air path clear. Do not cover the heater, obstruct its inlet or outlet, or fit improvised ducting.
- Choose a stable, non-combustible surface. Keep combustible materials, fuel containers and people clear of the hot outlet. Do not use where flammable vapours or combustible dust may be present.
- Refuel outdoors only after shutdown and cooling. Never refuel a running or hot heater.
- Do not rely on smell. Carbon monoxide is odourless. A thermostat, flame sensor or overheat cut-out does not make an unsuitable location safe.
The manuals describe temperature-limit protection and flame monitoring. This guide does not assume the heaters have tip-over protection or a built-in carbon monoxide detector. Read the HSE's carbon monoxide guidance and follow the model-specific instructions.
5. Check support and availability before ordering
Keep the heater clean and follow its maintenance schedule for fuel, filters and other service items. Shut it down, allow it to cool and isolate the electrical supply before maintenance; leave repairs outside the user manual to a competent technician.
Use our manuals and after-sales support page for help finding the right document or spare part. The HY125DKH / HY215DKH manual (PDF) is also available online. Check that any manual matches your machine and revision.
Check each product page for the current price, availability and dispatch estimate, particularly if you need heat for a specific job date. Pre-order items do not follow the same dispatch timing as in-stock products.
Quick questions
Can I use one to heat a house or closed garage?
No. These are not domestic room heaters. Do not use them in living or sleeping spaces, confined spaces or poorly ventilated areas. Ask for a suitable alternative for an enclosed workplace.
Does a diesel space heater need electricity?
Yes. All three models in this comparison specify a 230V supply as well as fuel.
Does 900m³ mean it will heat a 900m² floor area?
No. Cubic metres measure volume and include the height of the space. Square metres measure floor area. Treat coverage figures as a starting point, not a sizing guarantee.
Need help choosing? Contact Hyundai Power Products with your space dimensions and intended use, or call 01646 687 880. You can also browse the full space heater range.
Before ordering from the product cards below: open View Details to check suitability and the latest dispatch date. The models in this guide are currently offered on pre-order; confirm the date shown on the product page before placing your order.
