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20 Air Conditioning and Heating Terms Every Homeowner Should Know

February 07, 2014

We’ve all been there. You have to buy something technical and the salesperson is throwing about 100 different jargon words at you.

Your eyes start to glaze over. You start nodding your head pretending like you know what’s being said. It’s a horrible feeling being at the mercy of the salesperson.

It can happen often in our industry. But we don’t want you to feel threatened by our products and services.

Here are some common terms you need to hold your own with any heating and cooling contractor. We’ll separate them into air conditioner, heat pump and furnace terms.

Air conditioner terms

SEER (Seasonal Energy Efficiency Ratio):

A rating that measures air conditioner and heat pump cooling efficiency. The greater the SEER rating, the more expensive the air conditioner, but the less money you spend cooling your home. The minimum SEER rating for an air conditioner is 13 and the highest is 23 (and will continue to rise as technology improves).


A heat transfer liquid. It runs through your air conditioner indoor unit to absorb heat in your home’s air. This cools down the air which is then pushed throughout your home’s air ducts.

Evaporator coils:

Located in your air conditioner indoor unit. Refrigerant runs through the evaporator coils as your warm indoor air blows over the cold coils.

Condenser coils:

Located in your air conditioner outside unit. Refrigerant runs through outside coils as a fan blows over it to disperse the heat it gathered inside your home. Condenser coils get dirty over time, and need cleaning to properly disperse the heat. Not cleaning them results in higher energy bills.

Mini-split ductless system: An air conditioner that cuts out the middle man of using air ducts. It has one condenser unit and up to 4 evaporator units to send cold air into specific rooms. Think of it as a middle ground between a central air conditioner and a room air conditioner.

Two-stage air conditioner:

An air conditioner with two levels of operation: high for very hot days and low for mildly hot days. The low setting can meet your cooling demands about 80% of the time, so you’ll save more money and feel more comfortable because the air conditioner won’t have to run full blast all the time.

Heat pump terms

Air source heat pump:

An air conditioner that can also work in “reverse” to heat your home in the winter more efficiently than a furnace can. Perfect for warmer climates.

HSPF (Heating Seasonal Performance Factor):

The heating rating of a heat pump. Basically, it’s the SEER rating for winter. The minimum HSPF is 7.7. The most efficient heat pumps have an HSPF of between 8 and 10.

Strip heating (or resistance heating):

A backup electric heating source of a heat pump. It uses electrically heated metal coils, like the ones you’d find in a toaster.

Furnace terms

AFUE (Annual Fuel Utilization Efficiency):

A percentage showing you how efficient a furnace is. The minimum AFUE is 80% (meaning it uses 80% of gas to heat your home, the rest goes up the flue pipe.) The highest efficiency you can get is 98% AFUE. To put things in perspective an AFUE of 80% means that for every dollar you spend on heating 80 cents heats your home and 20 cents goes up the flue pipe, wasted.

Flue pipe:

Carries exhaust gases from the combustion process in the furnace to the outside of your home

Conventional furnace:

A mid-efficiency furnace (80%-83% AFUE).

Condensing furnace:

A high-efficiency furnace (90%+ AFUE).

Heat exchanger:

A metal cell or tube that is heated from flames and is designed to warm the air blown over it. So, it’s exchanging the heat from the heated tubes to the air. It also acts as a wall between the exhaust gases the furnace produces from the air circulated into your home.

Two-stage (dual-stage) furnace:

A furnace that has 2 settings for its burners: low and high. Two-stage furnaces cost more, but by running on low can keep you warm on slightly cold days without running on full blast.

Modulating furnace:

A furnace that can adjust it’s burners anywhere between off and high, giving it the ability to be more energy efficient.

Terms that fit in the above 3 sections

Air handler:

The inside unit of an air conditioner-only setup (no furnace) or heat pump. It contains the evaporator coils and the blower. Learn more about air handlers.


Located either in the air handler or in the bottom of a furnace. Pulls in air from your home and blows it over the heat exchanger and evaporator coils to either heat or cool the air respectfully.

Multi-speed blower:

Has a few different speeds (low, medium, high). It can ramp up or down the amount of air your need depending on what you need. It’s like having different gears on a car.

Variable speed blower:

A blower that can incrementally adjust how much air it blows based on your heating needs. It’s the most energy efficient type of blower.

Cool Today provides award-winning air conditioning service to Sarasota, Florida and the surrounding areas like Bradenton, Tampa, and Port Charlotte. If you have any questions, talk to one of our experts for help.

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