Customers depend on the expertise of contractors in selecting an air conditioner. Yet contractors generally over-size air conditioners by at least 20% and sometimes as much as 40%. Even the most conscientious contractor is driven to avoid call-backs (or even lawsuits). If the air conditioning system isn’t working properly (poorly sized duct delivery system, duct leaks, improper flow across the coils, improper charge) then the oversized air conditioner can mask the problem.
Unfortunately, many customers think that “bigger is better,” so in a competitive situation, the contractor proposing the proper size unit may lose the bid. Contractors are hesitant to adopt an unfamiliar method of sizing when the methods they’ve developed over the years have served them well… “I’ve done it this way for 30 years and I’ve never had a complaint.” It is no surprise then that air conditioners are oversized; however, the advantages of a properly sized air conditioner are so large that these barriers need to be overcome. Customers pay a price for oversized air conditioners in dollars and in comfort.
A properly sized air conditioner costs the customer less in equipment and in energy usage. The contractor should take the opportunity to discuss the value of the air conditioner based on the delivered efficiency and at a lower cost, but these opportunities, in most cases, are missed. Unfortunately we have a nation of oversized AC units causing massive amounts of wasted energy, reducing living comfort levels and creating horrific moisture, mildew and mold problems.