Airrex Diesel Heater Sizing Guide
Airrex Diesel Heater Sizing Guide
To choose the right diesel heater, calculate your space in cubic metres (m³) by multiplying floor length by width by ceiling height. The Airrex AH-500i heats spaces up to 1,500 m³, while the Airrex AH-900i covers spaces up to 2,500 m³. For larger locations, you can deploy multiple units or heat specific working zones rather than the entire building.
Step 1: Calculate Your Space Volume
Multiply your floor dimensions by the ceiling height to find your total volume:
- Length (m) × Width (m) × Height (m) = Total Cubic Metres (m³)
Volume Examples
- Small Workshop: 20m × 12m with a 4m ceiling = 960 m³
- Large Hall: 30m × 25m with a 3m ceiling = 2,250 m³
Step 2: Compare Airrex Models
| Model | Heating Output | Max Space | Fuel Consumption | Tank Capacity | Noise Level | Ideal Applications |
|---|---|---|---|---|---|---|
| Airrex AH-500i | 11 / 15 kW | 1,500 m³ | 1.05 – 1.42 L/h | 45 L | 47 dB | Workshops, garages, warehouses, barns, event tents, terraces |
| Airrex AH-900i | 19 / 24 kW | 2,500 m³ | 1.81 – 2.30 L/h | 70 L | 48 dB | Large warehouses, industrial halls, construction sites, large tents |
Both models are diesel-fired infrared heaters featuring a Blue Flame burner, an automatic thermostat, and dual power output options. They include built-in Wi-Fi for mobile app control and plug into a standard 230V socket, drawing only 50–60W of electricity during operation. They run on standard diesel or renewable HVO100 diesel fuel.
Step 3: Adjust for Real-World Conditions
Consider these variables before choosing your heater capacity:
- Insulation and Drafts: If your space has poor insulation, frequent open doors, or uninsulated steel/tent walls, choose a larger model or run the heater on its high output setting.
- Extreme Cold: For climates regularly dropping well below freezing, upgrade a size or plan to use multiple units.
- Zone Heating: If you only use a portion of a massive building, size the heater for that specific working area. Infrared heat warms people, floors, and machinery directly, so heating the whole volume is often unnecessary.
- Efficient Maintenance: In well-insulated spaces, the thermostat will cycle the heater on and off once the structures are warm, dropping actual fuel consumption well below maximum figures.
Practical Selection Examples
- Car Repair Garage (15m × 10m × 4m = 600 m³): Choose the AH-500i; it will typically run comfortably on its low setting.
- Standard Workshop (20m × 12m × 4m = 960 m³): Choose the AH-500i.
- Large Warehouse (30m × 25m × 3m = 2,250 m³): Choose the AH-900i.
- Industrial Hall (40m × 40m × 6m = 9,600 m³): Use multiple AH-900i units spaced across the floor, or allocate one unit per active working zone.
Why Choose Infrared Over Fan Heaters?
Traditional fan heaters blow hot air that immediately rises to the ceiling and escapes when garage doors open. Airrex infrared heaters project radiant heat straight into floors, walls, machinery, and people at ground level. These structures store the heat and radiate it back into the room. This ensures the temperature recovers almost instantly after a door cycles open. Because Airrex heaters do not use a fan, they operate quietly without creating drafts or kicking up dust.
Fuel Consumption and Running Costs
The built-in thermostat cycles the burner on and off to maintain your target temperature efficiently. For context, an insulated 500 m³ industrial hall maintained at +15°C against an outdoor temperature of 0°C requires only about 2.5 litres of diesel per day for maintenance heating.
Safety, Ventilation, and Warranty
- Fresh Air Requirements: Like all fuel-powered equipment, these heaters require adequate room ventilation to supply fresh air. An optional exhaust pipe can be installed to vent combustion gases directly outside.
- Safety Restrictions: Never operate diesel heaters in rooms where people sleep.
- Warranty Support: Every unit comes with a 2-year warranty, which expands to a 5-year warranty when you register your heater online. Annual servicing with original service kits maintains your coverage. Rex Nordic stocks 100% of spare parts at our Finnish and German hubs, offering rapid delivery across the region.
If you are still unsure which model suits your building, contact Rex Nordic or your local dealer for a custom sizing recommendation. For North American customers, these exact units are available under the model names AH-210i, AH-310i, and AH-810i.
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