What The Heck Do HVAC Efficiency Ratings Mean?

Dealing with HVAC systems can be overwhelming. Not only are there multiple aspects (furnaces, ducts, air conditioning, air filters, etc.) but the industry also comes with a language of its own. What in the world is a MERV? SEER?

To help homeowners and future homeowners, we’ve put together an easy guide on the four most common HVAC system ratings — MERV, SEER, AFUE and HSPF — including what they mean and what they’re used for.

MERV: Minimum Efficiency Rating Value

MERV ratings measure the efficiency of an air filter. They range from 1-16 — and the higher the MERV rating, the more it filters out (dust particles, pollen, mold, pet dander, etc.). A high MERV rating means the air filter has small pores, filtering out more, while a low rating means the air filter has large pores, which can let more pollutants and particles through the filter and back into your home’s air.

However, higher is not always better. Furnaces are built to operate with certain airflows, so using a different air filter than what it was built for can cause airflow problems. Because high MERV ratings mean the air filter has smaller pores, it can be more difficult for air to flow through it, leading to a more inefficient system. Your best bet is to go with the MERV efficiency ratings recommended by the furnace manufacturer.

To find out what kind of MERV you currently have, check the side of your filter or the packaging it came in. If you have a low rating and are interested in increasing it, call our HVAC experts or contact your contractor to be sure your furnace can handle it. A higher MERV rated filter is especially great for those that have asthma, allergies, or any other respiratory ailments.

SEER: Seasonal Energy Efficiency Ratio

The SEER rating measures the efficiency of air conditioners and heat pumps to help homeowners know how much energy their system is using. The higher the SEER, the less energy it will use, which means lower utility bills and less of an impact on the environment.

SEER is measured by the amount of cooling a system puts out for each unit of energy it consumes (like the amount of miles a car drives for each gallon of gas used). The highest SEER rating available is SEER 30, which would be applied to the most energy efficient system. The government requires a minimum SEER rating of 13.0 for newly installed systems, and to receive an Energy Star a system must have a SEER rating of at least 14.

AFUE: Average Fuel Utilization Efficiency

AFUE is a standard measurement of efficiency for gas and oil-fired furnaces. In basic terms, it measures the percentage of heat delivered to your house from each unit of fuel used.

For example, a 70 percent AFUE rating means the furnace converts 70 percent of the fuel/oil to heat your house (the other 30 percent gets sent out the flue).

In financial terms, think about it this way. A 70 percent rating means for every dollar spent, 70 cents goes toward heating your home and 30 cents gets wasted.

The higher the AFUE rating, the better. The minimum rating for newly installed furnaces is 78 percent, but the most efficient furnaces have AFUE ratings of up to 98.5 percent.

HSPF: Heating Seasonal Performance Factor

HSPF is a measurement used to gauge the heating efficiency of heat pumps. Heat pumps work by using the difference between outdoor and indoor air temperatures to cool and heat your home. Although they’re similar to air conditioners, heat pumps can cycle air in both directions, heating your home in the winter and cooling it in the summer.

The higher the HSPF rating, the more efficient and cost effective your heat pump will be to run. Translation: a higher rating means cheaper bills.

The minimum HSPF rating of a new heat pump is 7.7, and the most efficient heat pumps have an HSPF rating of 13. To qualify for an Energy Star Rating, a heat pump must have at least a rating of 8.2.

The different HVAC acronyms and ratings can be confusing, but remember the majority measure efficiency and are designed to help you get the most bang for your buck. Knowing where your equipment falls on the scale can help you to make the most out of your HVAC system without wasting money.