Calculating the Right Size HVAC Unit

Fitting an HVAC system to your home is a bit like Goldilocks finding the right porridge, you don’t want it too big or too small. However, finding that size takes more than a guess if you want your system to work properly. Discover why size matters so much, and the variables that go into calculating the proper size for your home.

Why Size Matters

Let’s start by exploring why size matters so much. When you have a properly sized system, your heating and cooling cycles will run for about 10 to 15 minutes, and you may have two or three cycles per hour. The expected service life is based on this kind of load.

If you have a system that’s too small, it’ll run nearly continually, wasting energy and adding wear to the system. An oversized system will shut down prematurely due to unusual temperatures within the system. This causes it to run more cycles per hour, adding tremendous strain due to the excessive starting. In either case, you’re left using more energy, increasing the number of repairs your system will need, and shortening its service life.

Fortunately, determining the size system your home needs is simply a matter of math, something experienced HVAC technicians understand. The following are the primary variables they’ll consider as they evaluate your home’s HVAC needs.

Serviceable Area

The foundation of sizing an HVAC system is the area it will serve. Some people stop at the square feet it’ll service, but that doesn’t take into account the actual volume of air that needs heating or cooling. Rather, you have to consider the height of your ceilings, which means the cubic area. This is especially important for homes with differing ceiling heights throughout the building.

Building Construction

You need to consider various parts of your home’s construction and its effect on how it transfers heat into or out of your home. Start by checking the amount of insulation your home has, and ensure it’s the proper amount for your climate zone.

Next, consider the number of exterior windows and doors and their construction. These can be a significant heat transfer source, especially in older homes.

Age and Condition of Your Ducts

You’ll need to consider your existing ductwork if you’re replacing your system. Is the ductwork effectively sealed to prevent air leakage? Older ductwork tends to have more issues with leaks than properly installed new systems.

Your option here is to either alter the load capacity of your system or replace or repair your current ductwork. Replacing ductwork can become expensive, but it will give you the best result in the long run if you’re dealing with ducts over 15 years old.

Heat Sources

Next, you’ll need to consider the various heat sources within your home and how they’re used. These can dramatically alter your HVAC needs, increasing the cooling capacity and decreasing the heating capacity.

Consider the number and kind of lights used throughout your home. The type of light bulb used makes the largest difference in your HVAC load.

Next, think about the big heat-generating appliances, like your oven, range, dishwasher, clothes washer and dryer, refrigerator, and any freezers. Don’t forget about other heat-generating appliances, like high-powered computing equipment.

Exterior Environment

Now we move to the environment around your home and the effect it has on your HVAC system. First, you’ll want to consider the orientation of your home compared to the sun. If you have a lot of south-facing windows, these will generally bring more radiant heat into your home throughout the day. This may increase your cooling capacity needs but decrease your heating needs.

Next, consider the amount of shade your home receives. If your home is constantly shaded, you’ll not need as much cooling capacity, but may need more heating capacity.

Number of Occupants

Finally, consider how many people occupy your home and how old they are. Every person acts as their own heat generator, so it alters the load capacity. Likewise, small children and elderly people tend to generate less heat than teenagers and young to middle-aged adults. Consider not only how many people actually reside in your home, but also if you frequently have visitors, such as if you run a home-based business.

When people around Brighton want reliable heating and air conditioning service, they call the experts at Lumberjack HVAC. Our team provides dependable AC and heating installation, repair, and maintenance along with humidity control solutions. Call to schedule your consultation with one of our friendly technicians today to determine the right size HVAC system for your home.

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