Tips for staying warm in unfinished structures

February 12, 2021

Vary the type of heating you use as the structure becomes more enclosed near completion

Low winter temperatures can drop worker productivity on a construction site, even crew members working within a building shell.

Creating a comfortable working environment via temporary heating can help keep workers moving freely and projects on schedule. United Rentals has outlined a range of portable heater options that contractors can use to warm up cold crews and temper spaces to maintain construction schedules.

One study showed that worker efficiency, measured by work output, starts to drop slightly when temperatures sink below approximately 50 degrees Fahrenheit. Efficiency drops by about half when the mercury hits zero degrees – and goes down from there.

“Temporary heating units differ in the amount of heat they generate and the amount of space they can warm,” said Eric Jarvis, regional product development manager of the United Rentals Power and HVAC group. “To get the most benefit, contractors should work with their temporary equipment provider to choose the right heater size. Sizing is a function of the volume of the building, temperature differential between outside and the temperature you want, tightness of the building and indoor activity, or how much heat is being generated by what’s being done inside.”

Choosing the right temporary heater

Ventilation, safety and space are three important considerations for contractors when choosing a temporary heat solution.

Make-up air heaters - These heaters are ideal for any size space heating the air with relatively low fuel consumption. They pressurize the space, evenly distributing heat while maintaining fresh air changes. The heaters can be powered by natural gas or propane, and can be placed inside or outside so long as fresh air enters unit. Heater options are based on BTUs with a typical range from 80k to 4.5M.

Indirect-fired heaters - These heaters are similar to a home’s furnace, requiring exhaust ventilation to outside air. They are powered by diesel fuel, natural gas or propane. The heaters provide 100% clean, dry air. There are no combustion by-products, moisture or other impurities released into the air. The heaters don’t have an open flame so air entering the heater space never comes in direct contact with a flame.

Electric heaters -These heaters should be used when absolutely no flame is permitted at the worksite, and when power is easily and readily available. Power requirements typically range from 120V to 480V. They need no ventilation and can be used when a building is mostly closed in. The heaters provide safe, clean and combustion-free heat.

Direct-fired heaters - These heaters provide a simple and economical solution. They are powered by natural gas or propane. The heaters should be used where there is plenty of ventilation, such as an office building with no windows installed. They have an exposed flame and should not be used in any area where there are combustible products.

“Anticipate changing the type of temporary heating you’re using during the course of a construction project. If you start with a direct-fired heater, for example, you may want to switch to a make-up air heater or an electric heater as the building gets closed in and the amount of natural ventilation decreases,” said Jarvis.

United Rentals has a comprehensive fleet of heaters for indoor applications, including electric and fuel-fired options, to help companies perform their required work safely, efficiently and effectively. United Rentals offers models ranging from 10-BTU portable heaters to large commercial heaters with up to 4.5M BTU.

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