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Do I Really Need a 24 SEER Unit?

In 1992, the Department of Energy first implemented air conditioning standards to encourage HVAC manufacturers to produce energy efficient systems that would lower utility bills for home- and business-owners. This standard became known as the Seasonal Energy Efficiency Ratio (SEER) and established itself as the primary system-efficiency benchmark in the HVAC industry.

What is SEER?

To understand what SEER is, we would first need to know what EER is. EER – Energy Efficiency Ratio – is a performance ratio that displays a system’s cooling capacity (Btu/hr) per watt of power used. Simplified, it is the cooling output divided by the energy consumed. The EER gives us a look at how efficiently a unit is operating at that very moment in time. By adding the seasonal component to EER, we can determine a system’s average operating efficiency throughout the entire cooling season.

The Fine Print

SEER was created by the HVAC industry, for the HVAC industry. That being said, it’s not surprising that the ratio is often misleading. Let’s break down some key points to be aware of:

  • The most common analogy is that SEER is like MPG – it is the maximum feasible efficiency rating under perfect operating conditions. Therefore, it is a variable, not a constant value. Just like you wouldn’t expect 20 MPG from a car going 100 MPH, you also shouldn’t expect maximum efficiency from an air conditioner when it is 95°F out.

  • SEER calculates an air conditioners performance at 82°F. In Greenville, SC, the average outdoor temperature in the summertime is around 88°F, with days reaching well into the 90°Fs. Above average outdoor temperatures will force a system to use vastly more energy to provide the same level of cooling, thus negating the perceiving energy savings.

  • Part of the key to making a system more efficient is to make heat transfer more efficient. Often, this is done by using thinner copper piping inside of the unit, which can make it more prone to wear and tear. If the copper begins to leak at inaccessible areas, this can lead to expensive repairs down the road.

  • Achieving the maximum SEER is only possible if an entire system is installed/replaced. For example, a 24 SEER condenser will never achieve the 24 SEER if it is operating with a 14 SEER evaporator.

The Truth

While higher SEER units are undoubtedly more energy efficient, often times it can be hard to justify the extra costs that come with them. Don’t be fooled by bad actors or fly-by-night salesmen telling you that a 24 SEER until will pay itself off in a few years. Always use a SEER Payback Calculator prior to purchasing a new unit. Lennox provides a basic calculator, whereas a more accurate calculator can be found on the Department of Energy’s website. Still not sure what you need? Call the pros at Miller HVAC today!

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