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6 Interesting Things You Must Know About Your A/C Unit

 |  Air Conditioning, Blog

When it comes to replacing an air conditioning system, up-front cost is often the top factor for homeowners. There are other things to know about your air conditioning system that can benefit your wallet, lower operating costs, and create greater peace of mind.

For example, a high-efficiency system might cost more to purchase, but your energy bills will be lower over the long term. According to ENERGY STAR, homeowners spend an average of $875 a year on heating and cooling. Replacing an older central A/C unit with an ENERGY STAR certified one can save you as much as 30% on future utility bills.

Small air conditioners cost in the low hundreds of dollars, while large central air units have a wide price range, depending on how they’re being used. Choosing the right one for your home, along with the right air conditioner service contractor with careful attention to efficiency, is important.

Other factors drive the unit’s overall efficiency, from the home’s square footage to regular maintenance, to understanding cooling capacity. Here you’ll learn six important things you might not know about your air conditioning unit.

1. Cooling Capacity Measurement

Tonnage is a common term associated with A/C cooling capacity, rather than a measure of weight. Tonnage identifies the amount of heat an air conditioner can remove from a given room in an hour. This capacity is measured in British Thermal Units and is compared to how long it takes to melt one ton of ice with a specific amount of heat. It takes 286,000 BTUs to melt a ton of ice in 24 hours. For instance, a one-ton A/C will remove 12,000 BTUs of heat in an hour.

2. Square Footage

An air conditioner’s cooling capacity should be directly related to room size. An appropriately sized air conditioner will effectively remove heat and humidity. Only some humidity will be removed if the unit is too big, plus you’ll be wasting energy and money on too large of a unit. For rooms up to 150 square feet, 5,000 Btus/hour is needed, while a room up to 400 square feet will require 12,000 BTUs.

Choose the smallest option you can get by with. If you can cool one room with a window unit or mini split system, this will use much less energy and cost less to purchase than a central air system. ENERGY STAR provides more information about properly sizing air conditioning units.


ENERGY STAR is the energy management program of the U.S. Environmental Protection Agency. Its efficiency guidelines enable people to save energy with efficient products, save money, and reduce atmospheric greenhouse gases. ENERGY STAR certified units are at least 15% more efficient than models which are not certified. Homeowners should be well-versed in energy efficiency when it comes to choosing the right air conditioner.

4. Energy Efficiency Ratio

Cooling system efficiency is expressed as Energy Efficiency Ratio, or EER, for room air conditioners. The higher the number, the more efficient the A/C is at a specific outdoor temperature. For central air, the Seasonal Energy Efficiency Ratio (SEER) is used. Both measurement systems incorporate cooling energy (in BTUs) and power consumption (Watt-hours) in their calculations.

5. Maintenance

Efficiency is improved through regular A/C maintenance. An Arizona air conditioning service such as Isley’s Home Service sends technicians who follow an efficiency checklist. They check/change filters and inspect coils, compressors, capacitors, and refrigerant. Without yearly maintenance, the A/C unit loses up to 5% of its efficiency each year. Maintenance appointments generally cost $70-$100, depending on the company and its plan, and can prevent much more expensive repairs later on.

6. Programmable Thermostats

A programmable thermostat can be set to a desired temperature at specific times of the day. If the house is empty, program a schedule to have the target temperature much higher. Then an hour before people are expected to return, it can be set to turn back on. That way, everyone stays comfortable and you save money. Even at 76° Fahrenheit, you can balance comfort with energy/cost savings.

Always consider these factors, the A/C unit’s efficiency rating, size, and the potential for annual savings and return. When you investigate available state or federal rebates, you can estimate yearly operating expenses.

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