With winters in full force in parts of the U.S., construction sites often use temporary heating systems to maintain optimal temperatures. The advantages are multifold – it allows employees’ comfort, prevents water pipes from freezing, and safeguards materials that require specific working temperature. However, if these heaters are not properly maintained, it could lead to serious and costly damage from fires. Here’s what you should know:

Types of Temporary Heating Units

It is critical that the correct type of heater is selected for the construction environment in which it will beused. The three primary types of temporary heating units are: Indirect Fired, Direct Fired, and Electric heating units.

  • Indirect fired heaters contain a burning flame within a specially constructed heating chamber. As cooler air passes over the heating chamber, warmer forced air is blown by an electrical fan into the building by temporary duct work. Generally, these types of heating units are used outdoors but can also be used indoors with proper ventilation. Placing such devices outdoors provides added safety by removing the flame/combustion part away from the building.
  • Direct fired heaters are an open flame heating device that has an internal fan blowing air over the flame to disperse warmer air. Because of the inherent hazard of an open flame, especially in an area near combustibles, the potential for a fire loss greatly increases. Wood frame and joisted masonry construction sites are strongly discouraged and should be used only under close supervision while equipped with additional safety provisions.
  • Electric heaters require power outlets and are common in smaller construction sites due to their limited capacity in providing heat to larger areas. They work by passing electricity through an element, which converts electrical to heat energy that is dissipated by a fan.

Safety Tips

  • Establish a written safety procedure for use and preventive maintenance on the units.
  • Provide proper training to all employees on the jobsite
  • Inspect all heating devices beforeusing; operate heaters in accordance with OEM specifications for safe usage.
  • Select the appropriate heating device based on the location in which it will be used.
  • Verify all heating devices are UL or CSA listed and equipped with proper safety controls such as high temperature shut off controls and tip over safety shut down controls.
  • Always maintain proper safe clearances from combustible materials – a minimum of 3’ clearance around all units.
  • Locate temporary heaters used in the vicinity of combustible tarpaulins, canvas, or similar coverings at least 10’ from the coverings. 
  • Securely fasten the coverings to prevent ignition or upsetting the heaterfrom wind or other force.
  • Refuel direct fired self-contained heating units outside and a safe distance of at least 50’ from the building.
  • Indirect fired units connected to flexible fuel lines (fuel hoses) should be inspected for abuse or general fatigue.
  • Protect fuel tanks on indirect fired units placed outdoors from damage from any type of motorized vehicle.
  • Post no-smoking signs on tanks.
  • Place all direct fired units on non-combustible surfaces that extend in all directions around the units – front, sides and back of the unit.
  • Prohibit the use of direct fired unitsduring non-working and/or unsupervised hours.

While temporary heating units have many benefits, they can be dangerous. Visit the Intact Inland Marine website for more Risk Control resources.