HVAC — heating, ventilation and air conditioning — symbolizes the technology and science of heat air and spreading it through a construction effectively. HVAC professionals at the residential marketplace specialize in the sale and service of furnaces, ac units and fan ventilation methods. Within the previous two decades HVAC technology has advanced in leaps and bounds, driven mainly with the dual concerns of energy efficiency and environmental awareness.
Heating Things Up
Home furnaces come in two basic types: gas-fired and electric. While gas technically lags in efficiency versus an electric furnace, the substantially lower cost of natural gas in most regions compared with power offsets the efficacy advantage and generally means lower monthly operating expenses. Even the gap in efficacy has impeded, as newer gas-fired condensing furnaces recover heat previously dropped in the combustion process. Forced-air furnaces are ranked on the AFUE scale. Short for Annual Fuel Utilization Efficiency, the present federal minimum for new furnaces is 78 percent. Condensing furnaces offer AFUE ratings above 90 percent.
Clearing the Air
Energy-efficient houses are built to be as airtight as possible. Indoor air may therefore become stagnant, as pollutants and airborne particulates collect. Low-tech choices include opening windows and doors at moderate weather or using an attic fan to exhaust stale air on cool nights. More recent inventions — heat recovery ventilators and energy recovery ventilators — induct fresh atmosphere while simultaneously exhausting an equal quantity of stagnant atmosphere to keep a neutral indoor air equilibrium and maintain household humidity and humidity.
Keeping It Cool
Central air conditioning, composed of an outside condenser and indoor air handler that distributes conditioned atmosphere through the whole house through duct work, is still the golden standard of residential cooling in terms of power and comfort. Window A/C units have been utilized to cool person rooms where retrofitting duct work for a central system isn’t feasible. Air conditioner efficiency is measured by a unit’s SEER rating. Short for Seasonal Energy Efficiency Ratio, the figure expresses the proportion of BTUs of heat energy extracted per hour versus the amount of electricity in kilowatt hours consumed. Current federal minimums require a SEER of 13 on all of the central air conditioners. Window units are exempt from the federal minimum, but most offer a standard SEER of 10.
Pumping It Out
Since a heat pump performs both the heating and cooling functions, the technology goes in a category all its own. Heat pumps heat and cool by moving heat energy from 1 area to another. In summer, an indoor evaporator coil circulating refrigerant consumes household heat and conveys it outside to be spread into the atmosphere by a condenser coil. In winter, the two coils trade functions and the exterior coil extracts latent heat energy from cold outside air, compresses it into refrigerant and moves it indoors to be spread into duct work from the indoor coil. Since no fuel is burnt, heat pumps pose none of the efficiency losses associated with combustion. In moderate climates where temperatures seldom drop below 35 degrees in winter, a heat pump transfers around four units of heat for every 1 unit of power it consumes.