The old “one-size-fits-all” philosophy
and “rule-of-thumb” sizing methods no longer apply.
Choosing the right heating and cooling system can be a daunting task.— new technologies and more options than ever before. When properly sized and properly installed, today’s high tech systems are quieter, cleaner, less prone to breakdown and far more efficient.
Improper installation is costly.
Before the era of tightly constructed energy-efficient homes, it didn’t much matter if a heating and cooling system was over-sized. And it was not unusual for contractors to install systems as much as two to four times the necessary capacity.
With today’s tight construction, proper sizing is critical. Among the problems associated with over-sized systems are:
- Higher than necessary installation costs
- Ten or more years of wasted energy dollars
- More frequent breakdowns
- Shorter equipment life
- Less comfort including:
- Wide temperature swings
- Cold clammy air conditioning
- Unhealthy mold growth
BEWARE the contractor who reads the old nameplate and simply “swaps the box.”
|The U.S. Department of Energy estimates that “well over half of HVAC contractors do not size heating and cooling equipment correctly.” And most builders use the lowest bidding contractor to install a single unit in every home regardless of differences in layout and location that should figure into the sizing calculation.
And even if your current system was properly sized when it was installed, your energy-saving improvements such as added insulation, additional caulking and sealing, more efficient replacement windows and doors — each may have changed the “load” requirements of your home. Even changes to your landscaping or window treatments can affect the sizing calculation.
Choosing a contractor who has the knowledge & who takes the time to properly determine the “load” required for your home is critical.*
The contractor you choose should strictly follow industry standards to determine the proper load requirements of your new system. This involves an extensive interview with the homeowner to determine comfort issues as well as detailed measurements and the calculation of specific formulas.
Among the factors that can affect the load calculation are:
- The size, shape and orientation of the home
- Insulation levels
- Window area, location and type
- The number and ages of occupants
- Family comfort preferences
- The types and efficiencies of lights and major heat-emitting appliances.
If your contractor suspects leakage in a home’s ductwork or “envelope” (frequently caused by home settlement over time), he or she should recommend further testing to measure heating loss from and infiltration into your home. If such problems go undetected, your new system will NEVER match the efficiencies promised on the manufacturer’s label.
If the contractor recommending a new system does not follow these procedures, if he does not review his calculations with you, your new system will likely be incorrectly sized.
ANY EXCUSE A CONTRACTOR GIVES FOR SKIPPING THESE IMPORTANT STEPS IS JUST FLAT-OUT WRONG! And your family will be living for the next decade or more suffering the consequences of his “guesswork.”
Next: How Heating/Cooling Systems Work