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Proper Heating & Air Conditioning Sizing

Proper Heating & Air Conditioning Sizing

Properly Sizing HVAC Equipment | Heating and Air Conditioning

In our blog you have often read about the importance of properly sizing HVAC Equipment. Today’s blog will attempt a more in depth explanation as to why it is important, and how accurate sizing for your home of office heating and air conditioning is determined. Problems in sizing isn’t necessarily due to your home’s characteristics, it may also be the contractor who is installing it.

Why Sizing is Important?

You will have heard this before on our blog, and it is necessary to repeat it for new readers and to lay the groundwork in our explanation.

Oversized heating and air conditioning systems cost more, waste energy, can provide reduced comfort levels and may create additional problems such as mold and mildew related to excessive humidity. This is due to the system’s short cycling. It doesn’t run long enough to properly remove adequate humidity from the indoor air. The elevated humidity makes it feel hotter than it really is during the cooling season, and lays the basis for mold and mildew to develop.

Undersized systems, on the other hand, will struggle to keep up with the demand, resulting in a heating and air conditioning system that runs too often, increasing energy use, increasing wear and tear on the system and resulting in premature failure. In addition, undersizing may cause overheating and can result in a house fire.

There are a number of factors that must be considered for “right sizing” a system. There are guidelines in place, (for example manual J and S). These guides are available as software for the contractor. You want to ensure that you hire an HVAC contractor who utilizes these guidelines to assist in sizing the system your home requires. The guidelines do allow some flexibility for the contractor when assessing your home’s unique properties, though this is not reason for a contractor to discount the guides altogether.

Each home is unique, and may have variable factors. For example, deciduous trees for shade on a southern exposure, a tree line providing a windbreak from cold north winds, UV windows, even the location of the system itself can affect the home’s needs.

A contractor who provides you with a bid and bases his sizing on the home’s square footage alone is not using the modern guidelines of the industry. Ensure you ask each contractor how they determined the proposed size of your system. If they base your 3 ton system on the fact you already have a 3 ton system, steer away from them, as well as the contractor who bases the size on square footage alone. Having a 3 ton system does not mean you need a 3 ton system. It may have been improperly sized during the original installation!

Furthermore, if you have upgraded insulation, windows or other, the required size HVAC may be smaller. As stated, there are a number of factors, as well as variables that must be considered; and a professional HVAC contractor will calculate these into sizing calculations for new or replacement heating and air conditioning.

The professionals of Cypress Heating and Air Conditioning utilize certified training; attend seminars and continuing education classes to ensure we are informed on the latest technology and up to date on improvements in our industry, and have a solid basis of education behind the principals of the HVAC industry. This enables us to provide you with the best service, and the greatest satisfaction possible.

Ductwork Sizing is Essential to System Performance

Right sizing must also include the ductwork. Duct work is comprised of the supply and return. Supply is the duct and registers that deliver conditioned air to each zone of the home. The return is attached to the inlet of the system and pulls air out of the conditioned spaces. The filter is located in the return system. The correct sizing of the ductwork, including the return, is essential for the distribution of the proper amount of air and the heating and air conditioning system’s performance and efficiency.

HVAC equipment SEER is based on the manufacturer’s efficiency rating which does not factor in the resistance of the duct system. An improperly designed and rated duct system will cause the system to work harder and less efficiently.

The Consortium for Energy recently stated that “most residential central air conditioning systems are not sized properly”. This reduces comfort, increases energy use and peak demand for electricity. The areas the group identified as major problems affecting a home’s comfort and efficiency were:

  • Oversized HVAC equipment – 47% •
  • Inadequate airflow – 70%
  • Improper refrigerant charge – 44% The increase in peak energy demand resulted in a 14% increase in existing homes and 25% in newly constructed homes. The improvement in the homeowner’s energy costs with properly installed systems and routine maintenance were 24% in existing homes and 35% in new construction. The results speak plainly, proper installation pays off.

Furthermore, when considering duct installation, you have the choice of flex duct, sheet metal or fiberglass board. Flex duct is low cost, fast to install and provides a solution for homes with no room for rigid duct. However, a problem occurs when improperly installed. A bad installation of flex duct increases friction and resistance due to bends, their degree and sag seriously reducing the system’s performance. Flex should be installed fully extended, removing excess length without compression of the duct.

When flex is installed improperly, the system has to run longer to reach the desired comfort level, increasing energy costs. The complexities of ducts, including a properly sized air return, require a thoroughly trained and knowledgeable HVAC professional. Cypress Heating and Air Conditioning provides the professionals with the expertise you require for all of the aspects of the heating and air conditioning industry.

The Air Return

Every central heating and air conditioning system require an air return capable of accommodating the same volume of air return that the system puts out. In addition, each interior door requires sufficient space beneath it to allow the return of the same amount of air flow that is delivered to it. The space beneath doors shouldn’t be blocked to achieve the proper performance and of the system.

By now it is apparent to you that replacing an HVAC system isn’t as simple as buying the same size and installing it. There are numerous considerations for achieving the right system for your home, and ensuring the proper duct system. This can be assured by hiring a qualified HVAC contractor, such as the professionals of Cypress Heating and Air Conditioning who are trained and knowledgeable, up-to-date and experienced, as well as dedicated to both your satisfaction and comfort.

Contact us for your HVAC replacement, new installation, HVAC repair, maintenance and other heating and air conditioning needs. When you use a Cypress professional you can be assured of our properly sizing HVAC equipment for your home or office. We serve Katy, Plano and the surrounding areas, and are a member of the BBB with an A+ rating.