Since heating and cooling a home comprises its largest energy expenditure, and the HVAC system its most costly component, it’s crucial to have a licensed HVAC professional do the load calculations before selecting a system. These calculations take into account the many characteristics of a structure that affect its heating and cooling requirements.
Skipping the load calculation often results in a system that’s either too big or too small, both of which reduce comfort, increase conditioning costs, and shorten the equipment’s lifetime. Over the decades, HVAC professionals have developed software tools that simplify this otherwise complex exercise.
The elements basic to a block load calculation include:
- Cubic footage
- Insulation levels of attic and walls
- Placement, size and efficiency of all windows
- Rate of air infiltration in the building’s shell
- Floorplan design, including number of levels
- Thermal preferences of occupants
- Ages and number of household members
- Heat producing activities indoors
- Landscaping factors
Homes with two or more levels require an additional room-by-room calculation. The HVAC professional will measure the square footage of each room on each level and incorporate the data into the ductwork sizing for the system. Skipping this part of the calculation results in uneven heating and cooling throughout the home.
It’s crucial to go through the calculation using Manual J software so that the size of the system matches the conditioning load. A system that’s too large will run in short cycles. It will turn on and off frequently, which increases energy consumption, particularly in the summer. In the cooling cycle, the short cycle leaves uncomfortable humidity behind.
During the winter, too large a heating system won’t deliver even heat to all the rooms, decreasing comfort. Frequent starts and stops, winter and summer, put more wear on many of the system’s parts. A system that’s too small will run longer than the manufacturer intended per cycle, stressing its components.
The experts at Bradbury Brothers Heating & Air Conditioning perform load calculations as part of the selection and installation process for new systems. We proudly provide HVAC services for The Woodlands, Conroe, Tomball, and Spring homeowners.
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