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If you are installing a new heating, ventilation and air conditioning system or upgrading an existing one, it is important to make sure that the new unit is properly sized. HVAVC systems that are too small will not heat and cool properly, break down more often and cost more to operate. Although it is tempting to oversize a unit, they often have the same problems that undersized units have. In addition, oversized units create humidity problems. According to the Department of Energy, faulty installation is a common reason for poor HVAC performance.

To make sure your new system is correctly sized and installed, ask your HVAC contractor to follow the load calculation guidelines recommended by the two most respected professional organizations in the U.S.: the American Society of Heating, Refrigerating and Air-Conditioning Engineers and Air Conditioning Contractors of America. The certified professionals at Aqua Plumbing & Air in Sarasota, Florida, use these guidelines and procedures to ensure proper load calculation, sizing and installation. Our technicians have advanced training and years of experience in installing all types of HVAC systems.

What Is HVAC Load?

Your HVAC contractor may speak with you about calculating load while planning your new system. Cooling load is the amount of heat that must be removed from a space to maintain a constant temperature. Heating load is the amount of heat that must be added to maintain a consistent temperature. The calculation is then used to determine the size of unit that will provide adequate heating and cooling at a reasonable cost.

Some contractors estimate load using the rule of thumb, a practice highly discouraged by industry experts. Load calculation requires precise evaluation of several factors that determine the size of unit and ducts, placement of components and other important aspects that affect comfort, price and reliability:

  • Square footage of building. Although the size of a building is not the only factor in determining load, the larger the building, the more cooling or heating load is required.
  • Orientation. West- and south-facing buildings receive more solar gain than north- and east-facing ones. In Florida, the summer afternoon sun can raise temperatures several degrees through windows, walls and doors, which increases the cooling load. In the winter, south-facing buildings gain heat from the sun, which reduces the heating load.
  • Local climate. The ambient temperature and amount of humidity affect load. High temperatures and humidity require more cooling power.
  • Number of doors and windows. Doors and windows allow transfer of heat, and windows are a major source of heat gain and loss.
  • Presence of shade trees and types of vegetation on the lot. Shade can lower outdoor temperatures around a building by as much as 6 degrees. Well-planned landscaping can reduce cooling load by up to 50%.
  • How many people occupy a room. People generate heat. The more people occupying a room, the greater the cooling need.
  • Purpose of a space. Kitchens, laundry rooms, electronics, lighting and appliances generate heat, requiring more cooling power.
  • Construction materials and condition of building shell. Some materials are more energy-efficient than others. Your HVAC contractor may conduct a blower door test to evaluate the building shell. Cracks allow infiltration of outside air.
  • Amount of insulation. Insulation is one of the most cost-effective ways to improve energy efficiency.

If a contractor’s quoted price is substantially lower than that of other contractors, or if the company insists that a smaller unit is sufficient for your needs, be wary. Shopping for the lowest price can end up costing more in the long run. If you are replacing a unit, the contractor must also consider the compatibility of the new unit with existing ductwork, thermostats, system controls, registers, grilles and other sources of ventilation. If you opt for a new, high-efficiency system, installation takes more time. The contractor must balance the system, run pressure tests and modify ductwork to ensure compatibility. Spending more time increases the cost of installation.

The technicians at Aqua Plumbing & Air take the time to talk about important factors that affect the choices you make about selecting a system suitable for your situation. We ask about your indoor climate requirements, budget and air quality needs. We discuss energy efficiency options to help you find a unit that balances cost with higher efficiency. We also discuss the advantages of installing advanced controls, such as programmable thermostats and smart systems. Our goal is to ensure your comfort with reliable equipment at a reasonable cost.

Problems With Undersized HVAC Systems

Undersized units often have many problems. The DOE reports that proper sizing and installation are key to HVAC efficiency. Units run longer to reach the temperature set point, which can overtax the compressor. During periods of extreme heat, they may not be able to keep indoor temperatures comfortable. Units may overheat and shut down. Utility bills are higher when a system must run longer to maintain a comfortable indoor environment.

Typically, undersized units break down more often, which not only causes inconvenience but can allow indoor temperatures and humidity to rise to levels that can endanger the health of building occupants. Undersized units often fail before reaching the normal span of service life. Customers are then faced with purchasing a new system.

Problems With Oversized HVAC Systems

Oversized units often have issues similar to undersized systems. Because they reach the set temperature quickly, they short-cycle, or start and stop more frequently, which wears out the compressor more quickly. Although the set temperature is quickly reached, the unit has not operated long enough to adequately remove humidity. Rooms may feel uncomfortable or clammy. Too much humidity creates an environment for mold to grow in ducts, near vents and in the living space. Ultimately, the system stops working properly and has a shortened service life. In addition, larger units cost more and must be paired with compatibly sized ducts. You will pay more for cooling power you do not need.

Energy-Efficient Options

There are several types of energy-efficient systems available for commercial and residential use. Air conditioners are rated by SEER, or seasonal energy efficiency ratio, which describes the amount of cooling required over a cooling season divided by the amount of energy required to power the unit during that time. The higher the SEER, the more energy-efficient the unit. Federal guidelines stipulate a minimum of SEER 14 for Florida. Carrier offers equipment up to SEER 26. Systems with higher SEER ratings usually cost more.

Ductless mini-splits. If your home does not have ducts, or if you are adding on and cannot connect to a ducted system, ductless mini-splits solve the problem. Available as both air conditioners and heat pumps, ductless units provide conditioned air to single rooms or zones. Each unit has its own controls, allowing independent temperature selection without affecting comfort in other spaces. Because there are no ducts, no cooling or heating is lost, which increases energy efficiency. In addition, pollutants are not carried from room to room through ducts.

Multistage units. A standard air conditioner operates at one speed, either on or off. When it reaches the desired temperature, it shuts off. As temperatures rise, it cycles on again. Variable-stage compressors adjust to the cooling load. When temperatures are lower, the unit runs at lower speeds, using less energy. When temperatures rise, it runs at higher speeds to meet cooling needs. Dual-stage compressors are more energy-efficient because they run at lower speeds approximately 80% of the time. They run longer, which minimizes swings in temperature. The result is better comfort and humidity control with less energy usage.

Variable speed blowers. In addition to variable-stage compressors, variable-speed blowers adjust the speed of the fans that blow air over the coils and into the living space. They are more energy-efficient because the speed adjusts according to the heating or cooling need. You will not feel blasts or pockets of hot or cold air. Indoor air quality improves because fans that run longer keep air circulating.

Why Choose Aqua Plumbing & Air?

A new HVAC system is a major investment that should last for years. Proper sizing and installation are key to performance and longevity. Aqua Plumbing & Air has been serving customers in Sarasota and nearby communities since 1974. We are a Carrier Factory Authorized Dealer, a prestigious designation that must be earned each year. Our technicians and staff undergo training by Carrier to provide superior customer service and technological expertise. We back our Carrier installations with a 100% customer satisfaction guarantee and are authorized to honor Carrier warranties. Our technicians are certified by NATE, the leading professional organization for technician certification.

We use industry guidelines for new installations, ensuring that your new system is properly sized and installed. After we complete an installation, we are available for maintenance checkups, repairs and any other needs you have.

If you are considering a new installation, call today to talk to one of our knowledgeable service technicians. Please note that we are available 24/7 for emergencies.

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