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HVACWhat You Should Know Before You BuyFurnace • Air Conditioning • Other HVAC SystemsBuying a FurnaceThe most important factor in selecting a furnace is the contractor you buy it from. A conscientious contractor will specify a furnace that is properly sized for the application, and meets the comfort, efficiency, and budget needs of the customer. A quality installation is then needed to provide quiet operation and balanced heat distribution. Equipment oversizing is the most common cause of noisy, imbalanced, drafty, and inefficient performance. Efficiency of gas furnaces is measured by the Department of Energy's Annualized Fuel Utilization Efficiency (AFUE) standard. Older style, standing pilot, atmospherically vented furnaces achieve an AFUE rating of 50% to 65%. Electronic ignitions improve the rating by about 5%. Modern draft induced furnaces achieve an efficiency rating of 80% AFUE, and condensing gas furnaces achieve an "Energy Star" efficiency of 90% to 96% AFUE. High efficiency furnaces can be vertically or side wall vented with PVC pipe, and require a condensate drain. Most manufacturers now offer two-stage furnaces at a very small premium. Low stage operates the furnace at two-thirds capacity for the first ten to fifteen minutes of operation. If heat demand is not satisfied in that time, the furnace will step to its full capacity until the space is heated. Staging provides quieter operation, more comfortable heating, higher efficiency, and less cycling of the furnace. Two-stage furnaces are strongly recommended for zone controlled applications. Typical modern furnaces are equipped with direct drive AC blower motors. Premium furnaces now offer digitally controlled direct current (DC) ECM blower motors that operate at a fraction of the energy costs of standard AC blower motors. In addition to efficiency, these blowers offer quieter operation and more precise air volume control. These blowers can also be set for very low constant air circulation volume. This provides extremely quiet operation for air cleaning and stratification reduction. We will gladly help you select the combination of features that fit the needs of you and your residence or business. back to HVAC main page Buying an Air Conditioning SystemCentral air conditioning is available either as packaged units (combined condensor and blower) or as split systems (remote condensing unit with indoor blower coil or furnace). As with heating, sizing is the most critical element of unit selection. Other important considerations are efficiency, noise levels, type of refrigerant, and staging. Cooling system efficiency is measured by the Seasonal Energy Efficiency Ratio (SEER). Use the SEER number to gauge the relative energy cost of cooling among different combinations of condensers and coils. The minimum allowable SEER rating is 10. We recommend a minimum rating of at least 12, and have systems available as high as 16. Sound levels of condensing units are measured in decibels (dB). Equipment rated at or below 70 dB is considered very quiet. Equipment above 80 dB is very noisy. The scale is logarithmic, so an 80 dB unit is ten times as loud as a 70 dB unit. Selection of quiet equipment, as well as careful placement away from noise sensitive areas, will avoid neighbor's complaints. Central air conditioning equipment is available with either R22 or R410A refrigerant. Although R22 is being phased out (as an ozone depleting chemical), replacement refrigerant should be available for the expected service life of equipment sold today. We do, however, recommend R410A. This new refrigerant is ozone friendly and performs very well in equipment designed for its use. Equipment for most applications is now available with the new refrigerant. Condensing units are available with either single or two-stage compressors. Two stage equipment is very useful in zonally controlled applications to prevent individual zones from overcooling during partial demand. back to HVAC main page Other Heating and Cooling SystemsHeat pumps are most simply described as air conditioning units with reversing valves to take heat out of the outside air during the winter and transfer it inside to provide warmth to the home or business. In choosing a heat pump, use the same selection criteria of efficiency, noise, refrigerant type, and staging that you would use to select an air conditioner. Heat pumps make the most sense in areas where natural gas is not available. In many structures, the heat pump does not provide all of the heat required on colder days and nights, so a back up source of heat is required—usually electric resistance heat, which is expensive to run and often requires an upgrade in service. Heat pumps are available as air to air, water source, or ground source. Hydronic heat uses a hot water or steam source run through a blower coil, radiator, or in-floor loop to provide heat. The hot water is provided by a boiler, water heater, heat pump, or solar system. Although we do not do radiant heating systems, we work with radiant heating contractors to install hybrid systems that combine the advantages of forced air systems with the comfort of in-floor systems. The blower coils used in hybrid systems allow for cooling, air filtration, and the ability to bring a space up to the desired temperature faster than with an in-floor system alone. back to HVAC main page |
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