Distribution Centre Heating: Radiant vs Warm Air
September 23, 2025
Factory floors are busy and tall. Some areas need steady background warmth. Others wrestle with dust or fumes. Doors open. Shifts change. Poor airflow planning leaves cold spots and high bills.
At Inergy Group we design warm air systems that hold even temperatures with clean, well-mixed air. We start with airflow, then add filtration matched to your process, destratification for height, the right level of fresh air, and controls that keep everything in tune.
When to Choose Warm Air Heating in Factories
Warm air suits large interiors where the goal is an even background temperature across the working area. It also anchors air quality work, because filtration and fresh air integrate cleanly with a warm air design. For the broader context and where warm air sits alongside other options, our commercial and industrial heating systems guide is a useful starting point.
There is a legal context. UK law asks employers to provide a reasonable indoor temperature. HSE guidance often uses 16 °C for most indoor work, or 13 °C for physically demanding tasks. Facilities teams can use those figures to select sensible setpoints and plan zoning strategies, as set out by the HSE.
Airflow: Throw, Mixing and Returns
Even temperatures begin with air that moves the way your building demands. Before anyone talks about plant size, the layout needs to deliver reach, mixing, and a reliable way back to the heaters.
Think about the day-to-day reality of your space. Do pallets and racking change monthly, or are the lines fixed for years. Are there mezzanines or overhead cranes that interrupt jets. Small planning decisions here avoid big running costs later, because the right throwing distance and return paths reduce the need for brute-force capacity.
- Throw and spread. Select discharge patterns and mounting heights that carry warm air across the floor rather than dumping it near the unit.
- Mixing and returns. Plan return paths so air comes back for reheating and does not stall behind machinery.
- Outlets. In ducted schemes, use grilles and diffusers that create stable jets at your mounting height.
- Unit heater layout. For open floors, place units so each jet overlaps the next, not fights it.
Commissioning turns drawings into comfort. We prove throw, mixing, and stability at handover, following the framework in CIBSE commissioning guidance.
Destratification for Tall Spaces
Warm air rises to the roof. In high bays, that is heat where no one works. Destratification fans blend warm air back to the working plane, so heaters run for fewer hours and setpoints hold with less effort.
Independent field research in active warehouses has reported double-digit cuts in heating energy, with one study indicating around a fifth less heating energy when destratification is sized and controlled correctly. Exact savings depend on height, volume, and fan control, but the direction is consistent.
Control matters. We design sensor bands at different heights so fans run in short, targeted bursts, not continuously. The aim is even temperature, not a constant draft. If you are weighing system types for big volumes, visit our comparison article on heating systems for warehouses.
Filtration that Fits the Task
Factories often need more than warmth. Dust, smoke, and mist make air quality central to comfort and compliance. A warm air system gives you space for filters without starving the fans, which is why filtration planning should happen alongside heating selection rather than after it.
Start by identifying the contaminants you care about. Ask operators where haze builds up, check housekeeping logs, and review any exposure monitoring. With a simple map of sources and particle sizes, you can match filter classes to risk and choose housings that are practical to maintain in your shifts.
Filtration Standards
- ISO 16890 replaced EN 779. Filters are rated by capture performance for PM10, PM2.5, and PM1, which lets you match the filter to the contaminant sizes you care about. See the standard explained by manufacturers such as Camfil.
- Energy matters. Filters with the same efficiency can have very different pressure drops. Eurovent’s guidance on selecting EN ISO 16890 filter classes explains both efficiency and energy use, so you pick a filter that cleans the air without wasting fan power. Find the framework on eurovent.eu.
Combining General Filtration with Source Capture
General filtration is not a substitute for local exhaust ventilation when a process creates harmful contaminants. The HSE’s LEV guide explains when to capture at source and how to commission it. Warm air then provides background comfort and the make-up air that balances pressure. If you want a primer on supply and extract options, our commercial ventilation guide is a useful reference.
Fresh Air and Make-Up Air
If you extract air for hygiene or a process, you must replace it. Do it right and comfort improves. Get it wrong and doors become inlets, cold edges appear, and fuel use rises.
A short site walk often reveals the story. Look for tight-closing doors that seem to fight you, notice where cardboard dust or welding smoke drifts, and ask staff which corners feel cold. These clues tell you whether the building is negative and where make-up air should enter to help, not harm.
- Balance supply and extract by zone so the building does not pull uncontrolled air through gaps.
- Pre-heat winter make-up air to avoid cold drafts at floor level.
- Filter outdoor air to a level that suits your risk profile, then mix with return air before supply.
HSE guidance is clear: employers must ensure adequate ventilation in enclosed workplaces. Warm air systems are a clean way to integrate that fresh air into heating.
Controls that Do the Heavy Lifting
Many savings come from control logic rather than new plant. The right schedules, setpoints, and interlocks stabilise temperatures and reduce run-hours without adding complexity for operators.
Our approach is to keep controls simple to use and easy to maintain, while still responding to doors, shift patterns, and height-related temperature bands. The focus is on predictable comfort first, then on optimisation once the basics are reliable.
- Zone schedules. Different areas, different times and temperatures.
- Set-back and reset. Lower setpoints out of hours and reset supply temperatures to avoid overshoot.
- Door interlocks. Reduce fan speed or pause heating while shutters are open.
- Multi-height sensors. Control to a temperature band that reflects stratification.
- Alarmed maintenance. Filters, burner run-hours, and fault prompts reduce downtime.
If your site plan is evolving, our HVAC service and maintenance tips cover the checks that protect performance and warranties.
Sizing and Selection
The numbers come first, but they only help when they reflect how your building actually runs. We start with a measured view of heat loss and air change, then we layer in production realities such as door cycles, machine waste heat, shift overlaps, and occupied zones.
Good sizing finds the sweet spot between comfort and consumption. Undersize, and heaters chase the setpoint all day. Oversize, and you pay for capacity that cycles on and off while wasting fuel. The right answer takes account of air quality too, because filtration classes and fresh air rates affect fan power and burner duty.
Selection then matches plant to layout. Unit heaters and ducted warm air each have strengths. Unit heaters suit open floors that benefit from overlapping jets. Ducted systems suit spaces that need specific discharge patterns, quieter operation, or defined returns. In both cases, we keep maintenance in mind so filters and belts are easy to access without stopping production lines.
Heat loss. Fabric, leakage, and door cycles dominate.
Internal gains. Machinery and process heat may carry part of the load.
Occupancy. Density and dwell times by zone shape priorities.
Air quality. Filtration class and fresh air rates define fan and heater capacity.
Modern warm air plant, sized and commissioned correctly, can deliver strong seasonal performance while holding steady setpoints. For a wider overview of choices and trade-offs, keep ourCommercial heating guide open as you plan.
Commissioning, Testing and Evidence
Commissioning is where performance becomes measurable. We verify throw, mixing, and temperatures at several heights before handover. We check pressure drops across filters, prove alarms, and document control responses to doors and schedules.
You receive an evidence pack that records settings and results for future optimisation, including drawings marked with measured throws and sensor locations. This structure follows the commissioning codes published by CIBSE, so anyone maintaining the system can see what “good” looks like.
Avoiding Pressure Drop
Dirty filters raise pressure drop. Fans draw more power and heaters work harder to keep up. Track filter condition and change on evidence, not guesswork, using logged pressure readings and alarm thresholds that reflect your shifts. Selecting energy-rated, ISO 16890-classified filters helps hold consumption down between changes.
Planned service should also include burner checks, gas rate, safety interlocks, flues, and proof that destratification and sensors behave as intended.
Quick Wins
- Tune destratification. Add sensor control, not a permanent on switch. Studies show savings when fans mix briefly and stop.
- Fix return paths. Many cold corners are return issues rather than heat output.
- Seal the envelope. Gaps around doors and voids create unwanted inlets.
- Reset schedules. Do not hold full setpoint during breaks or changeovers.
- Pick the right filter class. Use ISO 16890 ratings and Eurovent guidance to match risk and energy.
Common Questions
Is warm air too inefficient for high bays?
Not if you design for throw and returns, add destratification, and commission correctly. Evidence supports meaningful energy reductions when stratification is controlled in tall spaces.
How often should filters be changed?
It depends on contaminant load and run-hours. We track pressure drop and set alarms. Change filters before they push fan energy up.
What temperature should we aim for?
Use a sensible baseline. Many factories work well in the mid-teens Celsius for general tasks.
Do we need LEV as well as filtration?
If a process creates harmful dusts, fumes, or mists, yes. Capture at source with LEV, then use warm air and ventilation for comfort and balance.
Warm Air Heating in Factories from Inergy Group
Ready to even out temperatures and cut wasted run-hours? Start with a site survey. We will measure heat loss, check return paths, and size filtration and make-up air, then come back with a clear design and costs. If a hybrid makes sense, we can pair warm air with radiant heating. Get started on the Warm Air Heating systems page.
