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Heat When energy is added to an object or location, the motion of the molecules increases causing them to collide more frequently. The motion energy is converted into heat during the collisions. As more collisions occur more heat is released and the temperature of the object or location increases. Heat Exchangers This is the components in a gas furnace in which the actual combustion takes place. The internal metal jacket in a forced air furnace that often cracks or rusts through. Device that provides a practical means for the working fluid to heat or cool the conditioned fluid efficiently with out the two fluids mixing. Heat Gain The transfer of heat from outside to inside by means of conduction, convection, and radiation through all surfaces of a house. Heat Index The heat index is the combination of actual outside air temperature plus the affect of relative humidity to give an apparent temperature. Heat Loss The transfer of heat from inside to outside by means of conduction, convection, and radiation through all surfaces of a house. Heat Of Rejection The amount of heat rejected by the refrigerant in the condenser, which includes compressor heat. Heat Pump Refrigeration device that can be used to move heat to or from air or water, or to or from air to water then the water is used to heat or cool air. A reverse cycle refrigeration unit that can be used for heating or cooling. The outdoor unit associated with direct expansion equipment incorporating a compressor, coil, reversing valve and fan and provides heating and cooling. An air conditioning system that is capable of reversing the direction of refrigerant flow to provide either cooling or heating to the indoor space. Heat Pump (Air-To-Air) A device operating on a refrigeration cycle in which both evaporator and condenser are refrigerant/air heat exchangers. As a heating season heat recovery device, the evaporator transfers heat from the exhaust warm air to the refrigerant and the condenser transfers heat from the refrigerant to the incoming air. Arrangements are often made to allow the refrigerant flow to be reversed making the condenser the evaporator and vise versa - thus energy may be recovered in the cooling season. Heat Sink Object or location that is at a lower temperature than the heat source and receives the energy from the source. Heat Source Object or location that is at a higher temperature than other objects or locations. A body of air or liquid from which heat is collected. In an air source heat pump, the air outside the house is used as the heat source during the heating cycle. Heat Transfer The movement of energy as heat moving from a heat source to a heat sink. Heat Transfer Coefficient A proportionality constant in the heat transfer rate equation derived from the conditions of the fluid motion, the tube or fin surface geometry, and other thermodynamic properties. Heat Transfer Efficiency The ability of heat to transfer from one substance to another. Heat Transfer Fluid Any gas or liquid used by heat exchangers to transfer heat. Heat Transfer Rate Amount of energy that is moved from the heat source to the sink per an amount of time. Usually stated as Btu/hr in the English measurement system and Watts (Joules per second) in the Metric system. Heat-Absorbing Glass Window glass containing chemicals (with gray, bronze, or blue-green tint) which absorb light and heat radiation, and reduce glare and brightness. See also Tinted glass. Heating The transfer of energy to a space or to the air by the existence of a temperature gradient between the source and the space or air. This process may take different forms, i.e., conduction, convection or radiation. Heating Degree Day Term used by heating and cooling engineers to relate the typical climate conditions of different areas to the amount of energy needed to heat and cool a building. The base temperature is 65 degrees Fahrenheit. A heating degree day is counted for each degree below 65 degrees reached by the average daily outside temperatures in the winter. For example, if on a given winter day, the daily average temperature outdoors is 30 degrees, then there are 35 degrees below the base temperature of 65 degrees. Thus, there are 35 heating degree days for that day. Heating System Any device or system for heating a building usually, a furnace or boiler used to generate steam, hot water or hot air, a burner or air device that uses coal, oil, gas or electricity to heat water or air that is then circulated through the system, Types of heating systems include warm air, hot water, direct steam, radiant and electrical. Heating, Ventilation, And Air-Conditioning System (HVAC) A unit that regulates the distribution of heat, cooling and fresh air throughout a building. Heat-Strengthened Glass Glass that is reheated, after forming, to just below melting point, and then cooled, forming a compressed surface that increases its strength beyond that of typical annealed glass. Hepa An acronym for high efficiency particulate arrestance (filters). Hex Shingles Shingles that have the appearance of a hexagon after installation. HFC An acronym for Hydro fluorocarbon, which is a family of refrigerants that if released into the atmosphere causes destruction of the Earth's ozone layer. High Pressure Chiller A chiller that operates in a positive pressure for both the evaporator and condenser (measured in psig). Some high-pressure refrigerants include R-12, R-22, R-134a and R500. High Wind Area All areas along the coast that have been determined to be in high wind area. Hinged Windows Windows (casement, awning, and hopper) with an operating sash that has hinges on one side. See also Projected window. Hip The inclined external angle formed by the intersection of two sloping roof planes. Runs from the ridge to the eaves. Hip Roof A roof which slopes upward from all four sides of a building. Hip Shingles Shingles used to cover the inclined external angle formed by the intersection of two sloping roof planes. Hollow-Newel Stair A circular stairway with a well hole in the middle. Hood A canopy over a casement window, the part of a fireplace that projects over the hearth, a chimney cap that eliminates down draft, a canopy over a cooking appliance that is usually ventilated to control and disperse heat or offensive odors. Hopper Window with sash hinged at the bottom. Horizontal Parallel to the horizon. Horizontal Flow A type of furnace, installed on its "side," that draws in air from one side, heats it and sends the warm air out the other side. Most often used for installations in attics or crawl spaces. Horizontal Slider A window with a movable panel that slides horizontally. Hose Bib Faucet on the exterior of the house providing water to a garden hose. Hot Deck The top deck of the cooling tower where the condenser water returns to the tower prior to be cooled by evaporation, also referred to as the hot basin. |