Heating people, not air.
Human thermal comfort is a function of ambient air temperature and humidity, the cooling effect of air movement and the amount of infrared, or radiant, energy shining on and being absorbed by your skin and clothes.
When the sun emerges from behind a cloud, you immediately feel warmer due to the increase in radiant energy received from the sun, although there is little or no change in the surrounding ambient air temperature. This is because radiant energy, which travels at the speed of light, elevates the temperature of solid objects when it is absorbed, but does not heat the air through which it travels.
Humans at rest tend to be comfortable at around 70°F or 22°C. When the temperature drops, we put on more clothes, get more active or turn up the heat.
Turning up the heat often means heating the air that surrounds us with some sort of central or in-space (local) convective heater. Air passing or being forced over a warm element or a pipe filled with warm water or hot combustion products absorbs the element's heat and becomes warmer.
Turning up the heat can also mean increasing the amount of radiant energy shining on you and the objects around you. There is a broad range of surface radiant heaters (floor, ceiling and wall; electric, hot water and gas) and reflector focused radiant heaters (low intensity (temperature) tube gas heaters and high intensity (temperature) gas and electric heaters.)
In many situations radiant, in-space (local) heaters are dramatically more energy efficient than any other heating choice. The energy efficiency stems from several factors:
In situations where there is poor or no insulation (factories, warehouses, outside) and high air exchange (factories, warehouses, stores, outside) the heat losses are huge, and therefore so are the savings with radiant heat.
INFRARED SPOT HEATING
If it isn't a HotZone® heater, it isn't spot heat!
The amount of radiant energy transferred between 2 objects increases as function of the fourth power of the temperature difference of the emitting surface and the receiver. A 1500° difference transmits 16 times as much radiant energy as a 750° difference.
Low intensity infrared (radiant) heaters include tube heaters and other low temperature sources. As the amount of radiant energy being transferred is quite low, the heaters have to be quite large. Tube heaters and other low intensity heaters heat people and objects with radiant energy and the air around them with large convective losses.
High intensity infrared (radiant) heaters include ceramic gas burners, exposed and enclosed electric elements and quartz lamps. These high temperature sources produce a great deal of infrared radiation with greatly reduced convective losses. Unfortunately, most of these heaters have very simple, ineffective reflectors and therefore do not focus or direct the infrared radiation.
Schaefer's HotZone® heaters:
Delivering heat from a distance.
Because HotZone® heaters focus and direct the infrared energy into a beam:
Thermal comfort solutions using Schaefer's HotZone® heaters and appropriate heater controls:
©2008 Schaefer Ventilation Equipment. All rights reserved.