If you're among the 99 percent of homeowners who've never bought a new HVAC system, including buying a new furnace, the two most important things to know are that it's not a do-it-yourself project and that it requires engineering to adapt your new system to not only your home, but also to reconnect it to your existing ductwork and other mechanical systems. A professional HVAC contractor has the tools to help you select its energy efficiency and size, based on fairly technical characteristics of your home and current mechanical systems, as well as your budget considerations.
Furnaces must meet minimum standards for efficiency, known as their annual fuel utilization efficiency, or AFUE rating. The minimum starts at 78 AFUE, which means that 78 percent of the fuel the furnace consumes goes directly toward heating. The remaining 22 percent is wasted elsewhere in the process. The U.S. Department of Energy (DOE) will change the minimum AFUE from 78 to 80 as of January 1, 2015.
Systems with AFUE ratings as high as 98 percent are available. These sophisticated furnaces extract nearly all the heat the fuel creates by removing it from the water vapor, a natural by-product of burning gas. They remove the heat from the vapor and use it for heating, instead of sending it up the chimney.
A condensing furnace requires a more complex installation, but when you're buying a new furnace, it deserves serious consideration since it saves considerable energy dollars each time it runs. Furthermore, there may be additional government or utility rebates and incentives available on higher efficiency equipment. A well-informed contractor will be able to share with you all of the potential rebates and incentives available to you.
All furnaces need to be precisely sized using software such as Manual J and Manual D to calculate the size and configuration of the ductwork. An experienced HVAC contractor will carefully measure each room individually, factoring in both the orientation and amount of outdoor exposures each room has. Over- or under-sizing the system can decrease comfort, increase energy bills and hasten system wear. The size of these systems depends on your home's cubic footage, its overall energy efficiency, the floor plan design the nature of your home construction and insulation plus your temperature preferences and life style. Beware of quick load estimates that are based on inaccurate measures such as gross square footage, or were simply sized off the existing equipment. Using such methods will often lead to wrongly sized equipment as these methods incorporate large "fudge factors" or rely on the fact that the previous installing contractor did their homework and accurately sized the existing system.
The energy efficiency of the furnace you select also impacts the size you need, since a more efficient furnace delivers more heat. Paying for higher efficiency makes sense because you won't need as large a system, which saves money.
Tying It All Together
If you are replacing an older system, you will be reconnecting some of the older components of that system - like ductwork, wiring, gas piping, chimney and controls - with your new furnace. Since new furnaces may operate very differently from the units that they replace, it is important to be sure all these systems will continue to work in concert together. This requires engineering and an experienced local contractor familiar with the units installed in your area. Beware, not all furnace makes and models may be right for your home, consult the professionals!
The experts at P.K. Wadsworth Heating & Cooling can help you with buying a new furnace. We've provided trusted HVAC services for greater Cleveland homeowners since 1936.
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