Understanding HVAC System Efficiency Ratings Before You Buy

Various HVAC unti sizes and models

Shopping for a new HVAC system can often mean navigating your way through a jungle of unfamiliar acronyms and abbreviations.


If all this sounds like a foreign tongue, don’t worry. We’ve written this week’s blog post to help you understand the different HVAC system efficiency ratings before you buy.


SEER – or seasonal energy efficiency ratio – measures the efficiency of an air conditioner, allowing homeowners to see how much energy it would take to keep their house cool.

The higher the SEER number, the better the system is at cooling your home. And while an AC system with a high SEER number will likely cost more money in the short term, it will help you save on your energy bill in the long run.


HVAC filter being replacedMERV stands for “maximum efficiency reporting value,” and is the standard for determining the effectiveness of air filters.

The higher the MERV, the higher the quality of filtration. Most homes have MERV settings between 7 and 12, which means they can filter out things like lint, dust, pollen and mold spores. You’ll find filters with a MERV rating in the mid-teens working in hospitals and operating rooms.

But it’s important to remember that a higher MERV rating isn’t always better. A filter with a really high rating will have very small pores – to capture smaller particles – which can also restrict air flow. Your best bet is to go with the filter recommended for your heating and cooling system.


american-standard-92-furnaceThis is one of the key HVAC efficiency ratings, and probably the one we mention the most on this blog. AFUE stands for annual fuel utilization efficiency, and measures how well your furnace uses heat.

It’s a percentage rating; the closer you get to 100 percent, the better your furnace functions. If the AFUE rating on your system is 90 percent, that means 90 percent of the oil or gas the fuels your furnace goes back into heating your home, with the other 10 percent getting lost during combustion.

In financial terms, 90 cents of dollar you spend on heating really is heating your home. And if your furnace’s AFUE rating suddenly dropped to, say, 75 percent, you’d be losing $25 for every $100 you spent on heating.

However, it’s unlikely you’d have a furnace with an AFUE rating that low, unless your home has a particularly old heating unit. Since 1992, the U.S. Department of Energy has required furnace makers to hit an efficiency level of at least 78 percent.

In 2013, they bumped that number up to 80 percent, and most high-quality furnaces these days enter homes with a 98 percent AFUE rating.


Last on list of HVAC system efficiency ratings is HSPF, or heating seasonal performance factor. Just as a SEER rating only applies to cooling systems, HSPF is a metric that’s only used for heating.

It’s a ratio that weighs the BTU heat output of a furnace against the watt hours of electricity required to run the unit. The higher the ratio, the more efficient the system, and the less you’ll spend on energy.

When it comes time to install a new HVAC system, All Seasons Comfort Control can help. We’ve spent more than 15 years guiding Bucks and Montgomery county homeowners through the process of finding an HVAC system that will heat and cool their home without forcing them to spend too much.