AUSTIN TEXAS AIR CONDITIONING REPAIR - REPLACEMENT - SERVICE
Emergency A C Repair, Tune Ups & New Installs

The Importance of Proper AC/Heating System Design

HVAC systems are like any other electro-mechanical device, in that, they only work as advertised when they are installed properly. And even then, they don’t work at peak performance until they are fine-tuned after proper installation.

You may be asking yourself, “doesn’t every HVAC contractor design and install HVAC systems properly?”

Umm, no – We wish they did. Nothing would make me happier than to know every new system sold by the over 1,000 HVAC contractors in Central Texas, was configured, installed and fine-tuned for each and every customer. Seriously – that would be a dream. We would love for all families to have comfortable and efficient homes.

Sadly, only about 5% of the HVAC contractors in town make the industry proud.

When your HVAC contractor does not do a professional job, it has immediate and long-term consequences to you, such as…

  • Energy usage and costs that are higher than they should be
  • Substantially lower energy efficiency (SEER) than you purchased
  • Uncomfortable home with inconsistent temperatures from room to room
  • A central comfort system that is unnecessarily noisy and that annoyingly “blows” on occupants
  • High humidity that can support mold, mildew and other organic growth
  • Premature failure of expensive HVAC assets such as the blower motor, evaporator coil, and compressor.

This is not a one-size-fits-all kind of business.

There are no absolutes, bigger isn't always better and smaller isn't always most efficient. The size, effectiveness, and efficiency(SEER) of your heating and air conditioning equipment is substantially affected by the size and condition of the air ducts, the amount of attic insulation present, drafts and leaks in the home and whether windows are shaded from the hot Texas sun. A whole-house approach is the only way to ensure you are getting the right system for your home.

What is SEER?

SEER stands for “Seasonal Energy Efficiency Ratio”. A close analogy is “miles per gallon” in your car. A SEER rating is the ratio of the cooling output of an air conditioner over a typical cooling season, divided by the energy it consumed in Watt-Hours. It is important to distinguish, that it is the average calculated over a cooling season, and is figured using a constant indoor temperature and a variety of outdoor temperatures, ranging from the 60’s to the 100’s, thus simulating a typical season.

It is important to distinguish, that it is the average calculated over a cooling season, and is figured using a constant indoor temperature and a variety of outdoor temperatures, ranging from the 60’s to the 100’s, thus simulating a typical season. Using the MPG analogy, you can buy a high MPG car, but if your car is not tuned up regularly or you speed up and slow down and speed up and slow down as you drive, you are not going to get the high MPGs you think you should. Keep in mind that a SEER rating is a maximum rating, meaning it should be read as: this unit’s rating can be as high as 21 SEER. That doesn’t mean that it is ALWAYS 21 SEER. In fact, you may never experience 21 SEER, due to that rating being a factory-perfect testing lab. But with

Using the MPG analogy, you can buy a high MPG car, but if your car is not tuned up regularly or you speed up and slow down and speed up and slow down as you drive, you are not going to get the high MPGs you think you should. Keep in mind that a SEER rating is a maximum rating, meaning it should be read as: this unit’s rating can be as high as 21 SEER. That doesn’t mean that it is ALWAYS 21 SEER. In fact, you may never experience 21 SEER, due to that rating being a factory-perfect testing lab. But with the proper understanding of how to fine tune your system for your home, we can get close.

What about tonnage?

There is no relationship between tonnage and SEER. Tonnage is cooling capacity and SEER is an efficiency rating. For example, an “oversized” (in TONs) air conditioner will cool your house quicker, but it will use more electricity and will not remove humidity adequately. Contrary to popular belief – and intuition – long AC system run cycles are far more desirable and energy efficient than short run cycles. Once started, it takes about 10 to 15 minutes before your system is operating at peak efficiency and performance, and removing moisture from the air. Because an oversized system will often bring the temperature down to the thermostat setting in just a few minutes, your oversized system will never get to operate at peak performance and will end up “short-cycling” — starting and stopping over and over again – a fact which will cost you plenty in terms of comfort, utility bills and added repairs.

There is no relationship between tonnage and SEER. Tonnage is cooling capacity and SEER is an efficiency rating. As an example, A 80% efficient 3 ton (36000 BTU) unit will have an actual 28800 BTU output. A 3 ton 90% efficient unit would put out 32400 BTU, So the higher the SEER rating, the less rated input ton is required.

Ductwork – the air delivery system – is a factor

Ductwork that is improperly sized can cause uneven cooling and, quite possibly, introduce dust or mold into your home. If your duct system is not big enough to handle the increased airflow required by an “oversized” air conditioner, the evaporator coil may freeze and the system won’t work at all. Even if the coil doesn’t freeze, reduced airflow will impact operating efficiency and effectiveness and cause premature failure of expensive components, such as the compressor.

A Load test is the only way to size your system correctly. Eyeballing it is not good enough.

In order to get a system to perform at peak levels, the HVAC contractor will perform a heating and cooling load tests using a Manual-J calculation. Since these loads vary from room to room, the output from both the heating and air conditioning components will need to be considered alongside important information about your whole home, including:

  • Insulation levels
  • Home living area, construction, and orientation to the sun
  • Window area, construction, and type
  • Foundation and roof construction
  • And duct system location, size, supply, return airflow and condition

You will need to speak with an HVAC expert, like a McCullough Comfort Advisor, with years of training and experience in the field. They can properly design and configure a system unique to the needs of your home and, in turn, reduce energy usage and save you money without compromising health and safety of your family.

Once the design and configuration is complete, It’s time to install

A well-designed system can still be ruined with improper installation. It’s important to work with a contractor who employs experienced, licensed technicians with rigorous training. They need to know how to safely install reliable systems according to manufacturer speculations.

With McCullough, you can rest assured knowing that our technicians are some of the most experienced, well-trained heating and air conditioning technicians in the business. We pride ourselves in our Whole-house-as-a-system mindset.

We provide a structured continuing education program that keeps all service and installation personnel on top of the latest trends. Our technicians are pleasant and professional, too, and they’ll treat you and your home with respect.

Even if the guy down the street says he can offer you a better price, remember that an energy-efficient system is an investment in your home’s value and your family’s comfort and safety.

Maximize Your Energy Efficiency with the Proper HVAC Sizing

I hope you found this worthwhile, stay cool. Thanks for reading. 

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