What's the difference between BTU and CFM when comparing air conditioners?


Mike is right about the difference between BTUs and CFM, they are measurements of totally different factors. While you could say that CFM's can effect a unit's efficiency, I don't think it would be true in all cases.
However, I have been on several calls where the A/C was "not cooling" and found that the return air vent, at the system plenum, was completely blocked by the homeowner having stored boxes that covered the vent opening. While the air flow seemed to be ok at the registers, the blockage prevented the A/C from operating correctly, so the cooling was greatly impaired, probably because the evaporator was freezing up due to the restricted return air vent

Source(s): 20+ years experience...

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If your air conditioning system is 10 years old or more, you can bet it is wasting a lot of energy and costing you a lot of money. Ten or fifteen years ago, the Seasonal Energy Efficiency Rate (SEER) of the best available air conditioner was around 6 to 8, which is less than half of today's high efficiency models with a SEER of 19 to 20. SEER is the measurement of how much energy and money spent to run the air conditioner is actually being converted into cold air.

Older models also lose some of the SEER as they age. A model that was originally operated at 6 to 8 SEER, after many years, may be operating at SEERs as low as 6 or 4.

In addition to lower SEERs, older units are often improperly maintained. Dirt and moisture accumulate around the coils and ducts, while the A/C unit also becomes the breeding ground and dissemination device for mold and other common allergens, viruses, bacteria and many other pollutants. All...

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As a homeowner, there are many technical aspects of your home that often cause a lot of confusion for homeowners. From major appliances and tech gadgets to plumbing and electrical systems, it’s no surprise that most people look to the professionals for maintenance and repairs. However, as a homeowner, it’s also important for you to have a basic understanding of these complex parts of your house, especially your air conditioner. Learn a few key facts about air conditioning systems and determine which type of system may be the best fit for you.

What is HVAC? What Does HVAC Stand For? | Defining HVAC and AC

One of the most commonly asked questions homeowners ask is, “What’s the difference between AC and HVAC?” Ultimately, these acronyms are very similar. While AC stands for “air conditioning,” HVAC stands for “heating, ventilation and air conditioning.”
These two terms are often used interchangeably to describe any type of heating or cooling device in a home....

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According to the US Energy Information Administration (EIA), Americans consumed 97.7 quadrillion BTU (British thermal units) of energy in 2015 alone. The major energy consumers in the US include the:

Transportation sector (28%) Industrial sector (22%) Residential users (7%) Commercial users (4%) Energy generators (39%)

To promote energy conservation in America, the US Department of Energy (DOE) has been urging Americans to purchase and use energy-efficient appliances. This includes air conditioning system. In this article, we will discuss the differences between high efficiency air conditioners vs standard air conditioning.

Efficiency Rating (SEER)

SEER stands for Seasonal Energy Efficiency Ratio. It is a metric that is used to measure the cooling efficiency of an AC device. High efficiency air conditioners are typically assigned a high SEER ratio. Beginning Jan. 1, 2015, the EPA required all AC brands to have a minimum SEER rating of 14. Prior to this, air...

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It’s important to be able to control the temperature inside your car’s cabin. During the summer, you need air conditioning to ensure comfort and safety, and during the winter, you’ll need heat for the same reason. However, different cars have drastically different systems that achieve these goals. If you’re confused about the difference between climate control and air conditioning, you're not alone.

The difference between air conditioning and climate control

Air conditioning refers to manual control of the temperature of the air pumped into the cabin, as well as the speed of the fan. This is what most cars have – you manually turn on the air conditioner, select the temperature you want, and adjust the fan speed. Depending on your make and model, your passengers might have their own controls to achieve this (dual zone operation).

Climate control is different. This is a more advanced, computerized system. It basically automates everything, meaning that you don’t...

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Standard cubic feet per minute determines the weight of compressed air at 14.696 pounds per square inch, 60 degrees Fahrenheit and zero percent relative humidity. These are the conditions that occur at sea level. Even with so-called standard conditions, these measurements differ between the United States, Europe and other countries that use international units.

Cubic feet per minute indicates how much air is moved through the fan of an air conditioner, assuming the fan speed remains constant. Under theoretical conditions, if the fan remains constant, the same volume of air moves through the system from the time the fan starts until it stops.

A third designation, ACFM, or actual cubic feet per minute, takes into account pressure, humidity and temperature as air expands and compresses. Air contracts when the temperature drops and expands as the temperature rises. ACFM also takes into account changes in volume of air as conditions change.

Learn more about Math...
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BTUs determine how much cold air comes out of the unit, but problems can occur if the air conditioner is oversized for the space. The more cold air that comes out – the more area it needs to circulate to avoid giving the thermostat a false reading. If the unit is oversized, the cold air bounces off the wall back onto itself giving the thermostat a false reading – causing the compressor to shut off because the thermostat reads that the set temperature has been achieved. While the unit is off – the thermostat is able to read the room’s actual temperature, which kicks the compressor back on. This process will continue, causing the compressor to cycle off and on every two to three minutes, but never staying on long enough to effectively cool the room or remove uncomfortable humidity. Use AJ Madison’s to find the correct amount of BTUs for the area you would like to cool. This chart can also be used as a general guide. When cooling rooms with poor insulation, great rooms, or southern...

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Heat Pump vs Air Conditioner

Heat pumps and air conditioners share all internal components, but their mode of operation is quite different. The mode of operation for heat pumps is known as the reverse refrigeration cycle, whereas air conditioners operate on a regular vapor compression cycle.
However, there’s a host of other factors that differentiate the two.

Air conditioners are mainly used for cooling purposes, and maintaining conditions of comfort during high temperatures. As for heat pumps, their main function is to keep a room heated during very low atmospheric temperature conditions. However, the key difference between their uses is that a heat pump can be used for both heating and cooling purposes, while an air conditioner is strictly used to cool; although, if you are conscious about energy consumption, then an air conditioner will do better as its more energy efficient.

The condenser’s main function in a heat pump is to generate heating...

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Air conditioning Btu for Homeowners

Air conditioning Btu – Measure how much heat energy air conditioner unit produce.

An air conditioner manufacture needs away to compare the amount of heat is produce on specific period and need to know how much heat is remove on specific period (day, hour, minute).

They came up with measurement units. These measurement units are Btu and ton of refrigeration. This unit does not tell how much energy the air conditioner or furnace consumes in a season. To know how much energy air conditioner unit consumes, you need to know ac seer rating (for cooling).

I’ll explain how much energy the air conditioner units produce and what does 15000 Btu air conditioner unit means.

What is air conditioning Btu?

Btu is a British thermal unit. It’s a unit of heat energy.

Btu defines as the amount (quantity) of heat needed to raise the temperature of 1 pound of water to 1 degree F.

For example: when 5 lb of water is...

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Post 64

@Mrkpop: 25°C is approx 75°F (really 77), 212-75= 137°F; 137°F * 100 pounds equals 13,700 BTU's. You need to add the latent heat, I forget the value but you are said 1000 BTU/pound. So if that is the case, 100 pounds * 1000 BTU/pound = 100,000BTU's

100,000 BTU (latent) + 13,700 BTU (sensible) = 113,700 BTU's to heat 100 pounds of water to saturated steam (this assumes perfect insulation on the heating vessel).

Look at a steam table. The saturated steam is by definition 212°F or 100°C at 1 atmosphere. The values are approximate and depend on elevation.

Post 63

Which will absorb more BTUs an hour -- hot or colder air, and will the air rise according to its BTU content?

Post 62

I see a...

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The differences between a 115-volt air conditioner and a 230-volt air conditioner are not limited to the specific voltage consumed by each. They each have their own advantages and disadvantages, and you will have to decide which type fits better into your lifestyle and your surroundings.


A 115-volt air conditioner plugs into virtually any standard household outlet. A 230-volt air conditioner uses a specialized outlet, much like the type that a clothes dryer uses. This outlet must be professionally installed up to your local electrical codes, and you must figure in the cost to do into the overall price and convenience of the 230-volt air conditioner.

BTU Capacity

A 115-volt air conditioner will supply less cooling power than a 230-volt unit. Cooling is calculated in British Thermal Units, or BTUs as they are commonly abbreviated. Typically, the highest amount of BTU cooling power supplied by a 115-volt unit is about 12,000, while a 230-volt unit...

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