Is your HVAC unit a good fit for your home? We’re not talking about measuring the dimensions of your furnace or air conditioner. HVAC sizing is a term that refers to matching the BTU capacity of a new heating or cooling unit to the unique specifications and requirements of your house.

An undersized or oversized furnace or AC is no bargain. What’s worse, there’s no fix for the drawbacks that will persist as long as a unit with the wrong HVAC size is installed. These include:

• Chronically poor heating and cooling performance
• Higher monthly operating costs
• Increased system wear and tear
• Reduced service life of HVAC components

What’s Involved in HVAC Size and Sizing

HVAC sizing is based on the Manual J calculation published by the Air Conditioning Contractors of America (ACCA). Utilizing Manual J, a qualified HVAC professional will conduct a survey of the house and enter data, including these factors:

• Dimensions of the house. How many square feet of interior living space are there? How high are the ceilings?
• Occupants. Number and ages of residents.
• Local climate. Typical high and low temperatures per season are entered into the Manual J calculation, as well as other factors, including humidity.
• Orientation of the house. Does the home receive warmth from daily sunlight exposure? How many typical hours of sun per day does the house receive versus cool, shady conditions?
• Airtightness. How well sealed is the home to prevent heat loss in winter and heat gain in summer?
• HVAC ductwork. As a house ages, HVAC ducts often leak heated or cooled air. Are supply and return ducts intact?
• Amount and type of insulation. Attic insulation is particularly important. Many older homes still have the original insulation, which may not meet current EPA standards and should be upgraded.
• Lights and appliances. The number of lights as well as cooking appliances and other heat-generating devices influence indoor temperatures.

After all factors are entered with regard to HVAC size, the Manual J software calculates the exact required BTU capacity for HVAC components. This information is provided to the homeowner with suggestions to make an accurate, informed choice about a new heating and cooling system.

For more information about determining the correct HVAC size for your home, contact Jackson & Sons.