What Size HVAC Unit Do I Need?

Presidential Heating & Air Conditioning

Gaithersburg HVAC Contractors

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It is finally time to upgrade your HVAC system after many years of use. With so many modern options to choose from, you may be wondering what to get. Should you buy something larger so your system does not have to work as hard to heat and cool your home? Or should you opt for a smaller system to save money on your initial purchase? There are several factors to consider when determining what size HVAC system is best, such as the square footage of your home, the height of your ceilings, and how well your house is insulated. Learn what to look for when shopping for a new HVAC system.

Heating Unit Sizing

Older heating units (10 years old or older) are less efficient and not as reliable as newer models. When it is time for a replacement, choose a heating unit that will provide the best balance of comfort, efficiency, and low maintenance. This does not necessarily mean choosing the same size unit that you currently have in your home.

New additions, added insulation, and various other factors can change your sizing needs. As a general rule of thumb, if your home is well insulated and contains newer windows, you can safely (in most cases) choose a smaller size system that meets the specifications based on the total square footage of your home.

Most homes in the U.S. contain furnaces or heat pumps which are used to heat the home throughout the cooler months of the year. While most homeowners understand that choosing a heating unit that is too small for a home can force it to work round-the-clock, choosing an oversized heating unit is also not recommended. Oversized heat pumps do not run long enough to dehumidify the air, resulting in potential mold growth and a general “clammy” feeling in the air.

It is generally the installer’s responsibility to perform the proper sizing calculation for your home. Note that many older systems are oversized and often have two to four times the necessary capacity. As homeowners replace windows, add new insulation, and install weather stripping to windows, sizing requirements are often reduced.

When determining the proper size heating unit for your home, an installer will take several critical factors into consideration, such as the local climate, insulation levels, the size and shape of the home, air infiltration rates, the number of occupants, window types and locations, and the general comfort preferences of individuals living in the home.

The heating capacity of a furnace is measured in British Thermal Units (BTU). Known as Input BTU, furnaces are rated by the amount of fuel energy that is consumed when the heating unit is running. The production of heat, known as the Output BTU, is one of the primary factors when determining which heating unit is right for a home. Have an HVAC professional come to your home and provide an estimate for installing a new heat pump or furnace, and recommend a unit size.

Cooling Unit Sizing

If you live in a climate that experiences high temperatures, an air conditioning unit is a must. However, a cooling system is only effective if it is large enough to cool your home efficiently. You may be wondering, “what size HVAC unit do I need?” Like with heating units, AC systems are also based on several factors like the size of your home and how well it is insulated.

Air conditioners are labeled with the amount of BTUs they need. When you hire a technician to install your HVAC system, they will determine how your home’s square footage corresponds to the amount of BTUs. Variations can also occur which can alter your results. For example, if your home is heavily shaded by trees, you may need fewer BTUs to keep it cool.

The more people living in your home, the higher the BTUs need to be to keep the home cool due to the amount of body heat. If you frequently use the oven, stove, or microwave, you may also need more BTUs to compensate for the extra heat. If you are unsure about the size of the cooling unit you need, seek a professional opinion.

While you certainly do not want an air conditioner that is too small, you also do not want one that is too large. An oversized AC unit will cool your home more quickly, but there are some major drawbacks. As the AC cools the air, it also extracts moisture. If the unit does not run long enough, moisture cannot be extracted, leaving the air feeling clammy. An air conditioner that is too large will also cycle on and off frequently, wasting energy.

When sizing an air conditioner, professionals look at a number of factors, such as the square footage of the home, amount of sunshine the home receives, age of the home’s construction, existing ventilation system, the age and condition of windows, amount of shade from shrubs and trees, and the amount of insulation and degree of air sealing.

AC unit sizes are rated in tons of cooling capacity. 12,000 BTUs are equal to one ton of cooling per hour. While two AC units may offer the same tonnage, they may have different features and offer varying degrees of energy efficiency. In addition to tonnage, you will also want to pick a cooling unit that offers a great SEER rating to save energy.

Replacing an HVAC system is a major investment. Before making such a large financial decision, consider what size heating and cooling units are best for your home and family. As no two homes are alike, professionals must take a number of factors into consideration when recommending a replacement system. Problems can arise when your HVAC unit is too small or too large for the job. Both can cause a spike in your energy bills and negatively affect the comfort level of your home. Live comfortably while keeping heating and cooling costs under control by sizing your HVAC system properly.