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Want to save money? Don’t rely on a home inspector to catch HVAC issues

Heating and cooling (mostly cooling, in Texas) make up 40-60% of the average homeowner’s energy bills. With money and comfort on the line, why are major HVAC issues often overlooked when a home is inspected?

Consider this: Most city and third-party home inspectors know very little about a home’s comfort system. They have been trained to identify the need for further diagnosis, but their primary job is to ensure a system meets city code requirements. Unfortunately, an HVAC system that meets city code requirements does not necessarily operate efficiently.

Did you know that duct size is not part of the code – even though duct work accounts for, on average, about 60% of a total system’s operating efficiency? For example, a new 13 SEER system coupled with an old duct system designed for 10 SEER system will perform as efficiently as a 6 SEER system. This new system may meet the city’s code requirements, but it would actually increase your utility bills.

Inspectors, most anyway, will tell you if there are air leaks or dirt in the duct system, but how many will tell you the duct/distribution system is too small? Or that the filter is too small? How many can tell you the actual number of BTU/hour your system is operating at right now? The answer is, not many. Why, you ask? These are not covered in the code requirements. It’s as simple as that. The lesson here is that if there are issues with a system’s installation, don’t count on a city or third-party inspector to catch them. Whether you’re building a home, replacing your existing HVAC system or buying a home, hire a skilled HVAC professional to avoid costly oversights.

One of the most common system installation issues is duct sizing – more specifically, return duct sizing. The sizing of the return air grille, or filter grille, and return air duct are not covered in the mechanical code and are therefore not part of the city’s mechanical inspection process. Likewise, third-party home inspectors are not trained to calculate correct return air sizing. Only a trained HVAC technician is going to have the skills and tools to properly evaluate the system as a whole. Here are four of the factors most commonly overlooked by inspectors:

  1. Duct system: What type is it – sheet metal, Ductboard, flex? Is it sized correctly for the system? Is it installed according to the manufacturer’s recommendations? And remember, code requirements and manufacturer’s recommendations aren’t always the same. You should adhere to the more stringent set of recommendations.
  2. BTU/hour: Just because it’s a 4-ton system does not mean it is doing 4 tons of work. My personal findings are that most systems are operating at only 60% of their rated capacity, and many are even less efficient. These are conditions that can be corrected with proper duct remodeling, airflow settings and refrigerant charge.
  3. System age: We start to see major component failure numbers rise in systems that are 8 years or older.
  4. Filter size: Again, there is no code governing this, but you should have 1 square inch of filter for every 2 CFM. This means that a 3-ton system needs 600 square inches of filter. That equates to a 25 x 25 sized filter.

The point is this: City inspectors are trained to look for code violations. They are not trained to understand the correct operation and installation of an HVAC system. Home inspectors are very nearly the same with some (but very few) having a slightly better understanding of the system’s operation – but still with no training in the installation or design of a system. If you are considering purchasing a home and want a true understanding of how efficiently its HVAC system is operating, involve a reputable HVAC contractor. Whether you get the peace of mind that it’s operating efficiently or a heads up that you’ll need to invest in repair or replacement, you’ll be better off.

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