TEMP-AIR®

TL;DR: Quick Answer for Temporary Heating

• Why it matters: Sizing your heater correctly prevents energy waste, ensures worker safety, and maintains productivity.
• BTU Calculation: Multiply the room’s cubic volume by the desired temperature rise and the insulation factor to find your required BTUs.
• Direct vs. Indirect: Direct-fired heaters are highly efficient for open, ventilated spaces. Indirect-fired heaters provide clean, fume-free heat for enclosed areas.
• Top TEMP-AIR® Models: The Airrex AHSC-18R (1.5-ton heat pump) is perfect for versatile indoor climate control, while the Flagro FVO-400RC indirect heater easily handles massive warehouse applications.

When temperatures plummet on a job site, inside a warehouse, or during a sudden facility outage, securing reliable heat is no longer just about comfort—it is a matter of operational survival. If your temporary heating system is undersized, it will run constantly without ever reaching the target temperature, burning through fuel and leaving your workforce shivering. If it is oversized, the system will cycle inefficiently, creating uneven hot spots and skyrocketing your utility costs.

As a facility manager or contractor, how do you find the perfect balance?

By understanding your specific BTU requirements, accounting for airflow, and choosing the right heater technology, you can master your environment. Here is exactly how to select the correct portable industrial heater for your temporary space.

Why is selecting the right portable industrial heater important?

Selecting the right portable industrial heater is critical because it directly dictates your operational efficiency, cost savings, and worker safety. When an industrial heater is perfectly sized for its environment, it achieves the desired temperature quickly and maintains it effortlessly, extending the lifespan of the equipment while minimizing fuel waste.

Conversely, an incorrectly sized unit not only drives up your energy bills but also poses serious health and safety risks. As the Occupational Safety and Health Administration (OSHA) highlights, inadequate heating during cold-weather emergencies can lead to hypothermia, frostbite, and compromised worker focus. By getting your sizing right, you ensure your site stays productive, safe, and cost-effective.

What are BTUs, and how do you calculate them for temporary heaters?

A BTU (British Thermal Unit) is a standard measurement of heat output that dictates the exact amount of thermal energy required to raise the temperature of a space. As defined by authoritative energy organizations like the U.S. Energy Information Administration (EIA), one BTU is the quantity of heat required to raise the temperature of one pound of liquid water by one degree Fahrenheit. In industrial HVAC, it is the essential metric for sizing your equipment correctly.

To calculate the exact BTUs required for your temporary heaters, you must multiply the total cubic volume of the area by your desired temperature rise, and then multiply that number by the space’s insulation factor. Alternatively, if you want to skip the manual math, you can simply input the values needed into a BTU calculator to determine your required BTU output.

Step-by-step formula to calculate your heating requirement:

• Calculate Volume: Multiply the length, width, and height of your facility or enclosure to find the total cubic feet.
• Determine Temperature Rise: Subtract the current outdoor ambient temperature from your target indoor temperature.
• Apply the Insulation Factor: Multiply your total by a factor based on your structure’s heat retention (e.g., use a 1.2 factor for poorly insulated spaces or temporary event tents, which lose heat rapidly).

Example Calculation: If you are heating a 40′ × 30′ × 12′ space (14,400 cubic feet) requiring a 35°F temperature rise with poor insulation (1.2 factor), the math is 14,400 × 35 × 1.2. This means you require a portable industrial heater capable of producing at least 604,800 BTUs per hour.

What role does make-up air and insulation play?

Make-up air and insulation dictate how hard your heater has to work to maintain the temperatures you calculated. Make-up air replaces the conditioned air that escapes your structure through open doors, high foot traffic, or dust control ventilation systems. In poorly insulated environments, such as event tents or drafty warehouses, heat escapes rapidly. This creates the need for a portable heater with a higher BTU output to maintain consistent temperatures.

What is the difference between direct-fired and indirect-fired heaters?

The primary difference between direct-fired and indirect-fired heaters is how they handle combustion exhaust. Direct-fired heaters release warm air mixed with combustion gases directly into the space, whereas indirect-fired heaters use a heat exchanger to exhaust fumes outside, delivering 100% clean, dry heat indoors.

Here is how to choose between the two:

• Direct-Fired Heaters: Highly efficient (nearly 100%) and cost-effective. They are ideal for large, open, and heavily ventilated environments like outdoor construction sites where fresh air constantly circulates.
• Indirect-Fired Heaters: Deliver clean, fume-free warmth. They are the mandated choice for tightly enclosed areas, occupied event tents, or spaces where indoor air quality and moisture control are top priorities.

Which TEMP-AIR® portable heating models are best for your job site?

TEMP-AIR® Equipment Sales provides a comprehensive inventory of high-performance portable heaters and heat pumps designed to meet the exact BTU and safety requirements of your facility.

For reliable, versatile heating solutions, consider these top-tier models:

• Airrex AHSC-18R: Replacing the legacy AHSC-18P, this 1.5-ton portable heat pump is fully compliant with the 2025 EPA refrigerant regulations, utilizing eco-friendly R-454B. It delivers 16,800 BTU/h of heating and cooling, making it a perfect all-in-one climate control solution for offices, server rooms, and medical tents.
• Flagro FVO-400RC: An absolute powerhouse for large-scale industrial heating. This indirect-fired unit pumps out 390,000 BTUs of clean, breathable heat, making it the premier choice for warehouse temperature control and temporary construction enclosures.
• Flagro FVO-400LTRC: A rugged 3-in-1 heater trailer that provides 390,000 BTUs of heat, an 8kW generator, and a 15-foot light tower—ideal for off-grid jobsites battling brutal winter weather.
• Flagro F-1500T: A high-output direct-fired beast engineered for massive commercial spaces and concrete curing. It delivers a staggering 1,500,000 BTUs and features a dual-fuel selector valve, allowing you to switch between propane and natural gas effortlessly. With a 7,000 CFM blower and 100% flame safeguard system, it provides rapid, safe heat for the most demanding industrial projects.

Ready to optimize your facility’s climate? 

Connect with TEMP-AIR® Equipment Sales today for a personalized consultation, and let our experts help you secure the perfect, energy-efficient heating solution.

• Call us today at 1-888-535-8841
• Click here to qequest a quote on our website