Heating, Cooling and Filter Efficiency Numbers: Which Ones Matter?

June 22, 2021

What are efficiency or energy ratings? They tell you what numbers to look for when choosing an air conditioner, furnace, HVAC, air filter or heat pump system. But, sigh, do we really have to read them all?

Here are the numbers that matter most if you are interested in the highest energy-efficient systems:

  • Furnaces: AFUE number of 90-95
  • Air Conditioners, HVAC systems, Heat Pump Systems: SEER number higher than 21
  • Air or HEPA Filters: MERV number 13 or higher

We’ve given you more in depth how’s and whys of all the efficiency rating systems below.


Furnace and boilers rating system / AFUE: a higher AFUE number is better

Annual Fuel Utilization Efficiency (AFUE) is a rating system that measures the percentage of heat produced (BTu) per dollar of fuel used. The more your dollar savings and higher the efficiency, the higher rating the furnace has.

AFUE 78 – minimum rating for new units.

AFUE 80-85- mid efficiency.

AFUE 90-95 – high efficiency.

It’s easy to understand the numbers, for example: AFUE 90 means 90% goes to heating your home and 10% is wasted.


Air conditioning, HVAC systems and Heat Pumps rating system / SEER: a higher SEER number is better

Seasonal Energy Efficiency Ratio (SEER) is a rating system that measures the ratio of cooling output per energy used in watt-hours. The more your dollar savings and higher the efficiency, the higher rating the air conditioner (and heat pump).

SEER 13 – minimum rating for new units.

SEER 14.5 and higher – receives an Energy Star rating, meaning it is recognized as being energy efficient. Great!

SEER 21 – high efficiency.

Read our blog post about our world’s slow but final arrival to Eco Friendly Air Conditioners here.


Air Filter or HEPA Filter (for furnaces, HVACs, air conditioners and air purifiers) rating system / MERV: a higher MERV number is (mostly) better

Minimum Efficiency Reporting Value (MERV) is a rating system that measures the effectiveness of the air purification system or filters at capturing airborne particulates from .3 to 10 microns in size.

Yes, there are filters that will capture COVID-type particulates. Your existing furnace may not be compatible with a tight HEPA filter.

Does your furnace have a strong enough fan to push its air through a tight HEPA filter? Look up your furnace brand and age, or model number on the furnace and give Plumbhouse a call at the number below. We will help you find the best filter for your furnace.

MERV 7-8 – low efficiency filter

MERV 8-12 – captures most airborne particulates

MERV 13 or higher – captures COVID airborne particulates

MERV 13 – 16 – used in hospitals

Read more about HEPA filters, COVID particulates, whether your current furnace can even accept a HEPA filter and how you can increase the efficiency of your current air filter in our blog post ‘Will a HEPA Filter on my HVAC System Trap Airborne COVID type Particles?’ here.


Call us at Plumbhouse Plumbing (519) 453 4650 and tell us whether you’re interested in a heating or cooling system, or both, and we will help you navigate the meaning of their efficiencies.

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June 22, 2021 9:58 am Tags: , , , , ,

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