Gas Fired Radiant Heating

Gas Fired Radiant Heating

A common mistake that engineers and contractors make is using forced air heat for applications where infrared heat would be a better design option. There are many warehouses and other installations where infrared heat would provide a better comfort level and an energy savings of 50% over unit heaters. Radiant heat is the perfect application for high ceiling spaces, high ventilation or infiltration areas, spot heating and comfort for outdoor activities. Some applications include loading docks, warehouses, aircraft hangars, factories, outdoor restaurants, golf driving ranges, patios, sports arenas, firehouses, car washes, animal pens, pipe fabrication shops and auto body shops. There are many other applications that would benefit from this method of heating. An infrared heater will provide heat by warming surfaces, floors, and objects, not by heating the total volume of air in the space. Heat will then reradiate off of surfaces and some convection heating will occur. Natural convection will develop a heat differential in a space of approximately 8 degrees F for every ten foot difference in elevation in an open building space. A hot air system creates stratification of warm air at the ceiling.With radiant heat, a warm zone is established at the level where people will be working. People will feel more comfort even at a lower surrounding air temperature due to the radiant warmth. Radiant heaters for these applications are either low intensity tube heaters or high intensity direct-fired spot heaters. They can be operated on either natural gas or propane fuel. They are typically controlled by a wall mounted thermostat, time clock or a BMS system. The tube heaters consist of a burner box, radiant tubes and the reflector assembly. They are suspended from the ceiling with chains or cables and can be either vented or unvented. The tube heaters can be configured for the space requirements. The effective spread of the radiated heat is dependent on the unit height and input capacity. For a typical 40 ft straight tube heater mounted at 20” high, the effective width covered is approximately 20 feet. The heaters are provided with an air intake connection for applications where combustion air needs to be ducted directly to the heater (poor air quality or negative air pressures in the space). Tube heater components can be upgraded to stainless steel for certain corrosive applications.

To size infrared heat for a building, do a heat load estimate for the space and match the heater capacities to the load requirement. Locate the heaters around the perimeter of the space or where the heat is needed. Match the heater input to the mounting height and clearances available. Put the burner end of the heater near the largest heat loss since the tubes closest to the heater are warmer. Two stage tube heaters available offer even greater comfort levels for the occupants and energy savings for the building operator. You must keep the proper clearance to combustibles for all heaters. All heaters specify the dimensions for clearances in the equipment selection guides. Heaters should not be used in an explosive environment. Follow ventilation code requirements for gas burning equipment.

Stop by the ATI warehouse for a live demonstration of the effectiveness of a radiant heater versus a propeller type unit heater. For your design help, see the Detroit Radiant website for the handy Engineering & Application Guide as well as specifications and CAD details for your download.

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