If you are shopping around for a new HVAC system, you are likely to have come across SEER ratings. Understanding SEER ratings is the key to energy savings, but they can be a little confusing. In this article you will learn everything you need to know about how to interpret SEER numbers. 
What is SEER?
SEER is an abbreviation ofr Seasonal Energy Efficiency Ratio. This is a measurement of how economically and efficiently the HVAC unit has the capacity to perform. Essentially, the rating signifies the cooling capacity provided by every energy unit used. The more efficient the HVAC unit, the higher the SEER rating.
What is the Highest SEER Rating?
There are split air conditioning systems that have a SEER rating of 25 and above. Unfortunately, these systems are not always the most cost-effective. Generally, the highest SEER rating means that the unit will need several compressors and larger coils, even in residential systems. A SEER rating at the mandated minimum could actually be the most cost-effective solution when you are looking to install a new system or replace an old HVAC system.
If you need an extended cooling season, it may become more practical to consider a higher SEER rated unit as the increased energy use would outweigh the higher initial costs.
There are some types of air conditioning units such as mini-split, ductless units that have a SEER rating of 22. Ducted HVAC systems are not quite this efficient yet. The main challenge with a ducted system is that there are cooling losses resulting from operational inefficiencies (for one the cooler air needs to travel long distances), with up to 20% lower than the posted ratings. Some ground-source units are available with a rating of up to 75 SEER. The main drawback with this system is that the efficiency of the heat pump relies on the ground or water source temperature. This means that your local climate could significantly reduce the efficiency.
Choosing the Right SEER Rating for you:
To keep cool for less cash, you need to choose the right SEER rating. The rating is a good gauge of the seasonal performance of the HVAC system while the Energy Efficiency Ratio (EER) offers a better insight into the operational efficiency when the system was tested under controlled and set conditions.
The maximum SEER Rating is calculated by averaging the maximum EER over the full range of the predicted seasonal temperatures for a specific location. Generally, the higher the SEER, the higher the purchase cost. The difference in this initial cost is usually recouped in your significantly lower energy bills. You should also see far lower costs of maintenance and any repairs.
There are several factors to consider in determining which SEER rating is best suited for your needs. Obviously, if you choose too high a rating, it will take you far longer to recoup the initial capital outlay, but if you choose too low a rating, it may not be practical for your home. The best way to determine which SEER rating is right for your particular location is to consult with a professional licensed local HVAC technician. Someone with local expertise will be able to assist you in choosing the best option for your HVAC replacement or upgrade.