Special HVAC Circumstances? Think Low-Intensity Radiant Heat

By Michelle Fox, Product Support Assistant, Detroit Radiant Products, Warren Mich. -- Consulting-Specifying Engineer, 11/1/2006

When one thinks about providing heat for a building, forced air is probably the first solution that comes to mind. But in certain circumstances, notably large, open settings or operations where doors are frequently opened and closed, gas-fired infrared heating may provide a more efficient system. Studies have found that gas-fired infrared heating can save 20% to 50% in fuel consumption over forced air heating.

Low-intensity gas-fired infrared heating systems operate with an enclosed flame, where, when heat is required, the burner control box ignites a gas/air mixture and hot gases are pushed through steel radiant tubing by an internal fan. As these gases pass through the assembly, the tubing is heated and emits infrared energy, which is then directed toward the floor by highly polished reflectors. This energy is absorbed by objects in its path, such as the floor, machinery and people. Objects in the path of the infrared energy in turn re-radiate this heat to create a comfort zone at the floor level. This method of heating allows the source of heat to begin at the floor level and not the ceiling.

Furthermore, with infrared heat the floor acts as a reservoir. When doors are opened, the slab looses very little of its heat. When the doors then close, the huge mass acts as a heat exchanger to reheat the cold air. This creates the most efficient and effective heating method under the diverse conditions present in most commercial and industrial applications.

Two-stage control technology is also available that can lower fuel costs by another 12%.Vacuum-style systems offer further flexibility and configuration options.

That being said, there are a number of things to consider when using radiant infrared heat: Care needs to be taken when laying out the system to maintain clearances to combustibles. Infrared radiant heaters require higher clearances than forced air units. A mounting height of 10-ft. or higher is recommended.

A critical safety factor to consider before installing an infrared heating system is clearances to combustibles. Such clearance is defined as the minimum distance that must be maintained between the radiant tube heater surface and the combustible item. Considerations must also be made for moving objects around the heater and materials that have lower temperature ratings, such as plastics.

It is also important to provide warnings to alert individuals to potential hazards and safety actions. Signs must be posted to specify maximum stacking heights in order to maintain clearances to combustibles, especially in storage areas.

If your owner/operator can live with a small upfront investment, radiant heating might be a wise choice. The initial cost of a standard, 40-ft.-long unitary tube heater will run approximately $1,100. Therefore, upfront costs are higher than traditional heating methods. Gas line connections must be considered. However, this investment will pay for itself over a short period of time due to the energy saving benefits of radiant heaters.