South Texas is famous for its vast pastures, longhorn cattle and hot summers. To help withstand the heat, customers are turning down their thermostats to keep them cool and comfortable. How does this affect utility bills and budgets?

Those lower thermostat settings will result in higher energy usage and bills. why? Air conditioning may account for 50% or more of summer energy bills! Ensuring that your AC equipment is well maintained and operating efficiently is the key to preventing the sticker from vibrating when the electricity bill arrives.

Recently, I had a conversation with Tom Damiani of the comfort design company in Damiani, San Antonio. I asked him a few questions related to HVAC, about how to reduce energy consumption while keeping the home comfortable. Read on to learn about air conditioning repair and replacement, how often to replace filters, whether to close vents and doors to unoccupied rooms, and more.

Me: How do customers know if they need to repair or completely replace the AC power?

Tom: Usually, this is the threshold for unit age and unit type. Each manufacturer offers a variety of models of systems, from architectural level (installed by the builder during construction, possibly a low-cost model) to high-end. Depending on the type of equipment you have, it may be near the end of its useful life. Homeowners can view repair costs and replacement costs to help them make a decision. When the equipment has been used for about 10 years and the repair cost is hundreds or thousands of dollars, in the long run, the replacement of the equipment may benefit the customer.

Me: If I always keep the same temperature setting in summer, will my energy bill increase year by year?

Tom: As the unit ages, their work efficiency may not be as good as before. They have a more challenging time to maintain the temperature you set. Usually, I find that the piping system may be the culprit leading to higher bills. As the insulating material around the flexible duct begins to degrade, it becomes more difficult for this device to keep your house cool.  

Me: Should the vent or door of an empty room be closed?

Tom: The device is designed according to a certain static pressure, so closing and sealing the vent and inner door will increase the pressure of the device and reduce the overall airflow. Doing so may cause leakage of resistors and coils, compressor failure, and motor and capacitor failures because the AC device works too hard. The return air volume of the unit must match the output volume of the system.

Me: Is the proper duct size important to energy efficiency?

Tom: Pipes of the same size in the whole house are not very efficient. You must check the amount of space in the room you want to cool, which direction it faces, and how many windows there are in that room. Two rooms of the same size can have pipe systems of different sizes, depending on the direction and the number of windows. The duct system should be designed according to the cubic feet per minute (CFM) requirements of the room, and then you can control the dampers and move the air to where you need it, and avoid hot and cold spots. Be sure to seek the help of licensed and bonded professionals. This action will help homeowners reduce their utility bills.

Me: Why does the line of my external device freeze?

Tom: The device may not have enough refrigerant, the piping system may be too small, the return air volume may be seriously insufficient, or the filter may be clogged.

Me: Should customers check the air filter at least twice a month in summer?

Tom: Of course. My friends always ask me, "How often should I change the filter?" My answer is, "How often do you want to see me?" The more efficient 5-inch filter recommended by your particular air conditioner manufacturer can be every six Change once a month. The one-inch filter on the device or return grill should be replaced at least once a month. If you have an older house or a lot of traffic and pets, then these filters may need to be replaced twice a month.

Me: We recommend setting the temperature of the air conditioning system to 78 degrees, so that customers can save on cooling costs in summer. Although it is not recommended, we know that some customers may set it to be cooler than this. For best efficiency, should the customer set the thermostat at a position that is approximately 20 degrees away from the outside temperature? For example, if the outdoor temperature is 101 degrees, should the thermostat be set at or close to 81 degrees?

Tom: This is a fact. The load calculation is based on design standards. This must consider the size of the house, the number of windows and other factors. A difference away from 20 degrees means that the air conditioner works harder and longer. If a customer chooses a device that is too large to keep the house cool, they may experience higher than normal humidity in the home. Then the device is turned on more frequently, leading to higher bills.

Me: What is a variable speed compressor?

Tom: Variable speed compressors provide incredible comfort. They need to go through 65-80 stages to get great comfort, and they can have a seasonal energy efficiency ratio (SEER) in their 20s. Unlike equipment that runs at 100% capacity, variable speed compressors can cycle through various stages to meet the temperature required by the home. This helps save money because the device can consume less electricity.

Me: What role does return air play in energy efficiency?

Tom: Most families don't have enough return air. The system is designed to blow out as much air as possible to make the equipment work properly. If the device cannot suck back the same amount of air it exhausts, it will start sucking air out of the cracks and air gaps around windows, doors, and even attics. These areas bring more dust into the house. Evidence of air infiltration is the accumulation of dirt on floors, window sills, blinds and curtains, and near doors. This is because the air conditioner is sucking in air from the outside, which is a clear sign that there is a problem with the return air. These households need to change the air filter more frequently. Inhaling air through doors and windows will also bring in warm air from outside, making your air conditioner work harder. It is important not to close the vents or doors of empty rooms with no return air.  

According to data from energy.gov, today's best air conditioners require 30% to 50% less energy to produce the same amount of cooling than air conditioners made in the mid-1970s. Even if your air conditioner is only 10 years old, you can save 20% to 40% of cooling energy costs by changing to a newer, more efficient model.

If there is a problem with your air conditioner, it is best to seek multiple quotations to repair or replace your equipment. Keep in mind that when purchasing a new air conditioning system, you may be eligible for a tax refund for CPS energy and/or federal tax credits.

For more tips on air conditioning, please visit the CPS Energy website or energy.gov.

Special thanks to our subject matter experts for helping to write the content of this blog. CPS Energy does not promote or recommend contractors or suppliers. Instead, we encourage customers to seek multiple service quotations.

John is a member of CPS Energy's corporate communications team.

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