Determine The HVAC Size For My Home

Determine The HVAC Size For My Home


One of the most expensive pieces of equipment supporting your home’s comfort and function is the HVAC system. Whether you’re replacing or upgrading an old unit or installing your home’s first air conditioning unit, the most important decision you’ll make is the size of that unit. Let’s explore the why and how so that you can make the best selection.


Why Size Matters In HVAC Installation

Many consumers begin a purchase by collecting info from other consumers. This is fine for branding purposes, but not for sizing. It’s crucial that you not base your home’s air conditioning needs on what friends, family, and neighbors have installed. Size matters, and what’s right for someone else’s home may be completely wrong for your home.

Buying an HVAC system that’s too big is a waste of money in the initial purchase. The difference in price can equate to hundreds to thousands of wasted dollars. Once installed, a unit that’s too big uses more energy. In turn, your electric bill is higher for the life of the unit, which can equate to thousands of dollars in the long run, as described on Springdale HVAC.

On the other hand, selecting an air conditioning unit that’s too small typically results in an array of temperature regulation problems. One room may be cooler than the other, and sizable rooms may feel too warm.

In either case, selecting the wrong size for your HVAC unit means that it doesn’t work efficiently and will likely suffer premature wear and tear that will leave you a lot of unnecessary maintenance, repair, and replacement costs.

Figuring out a general best unit size involves 2 basic steps. But, you’ll also see a lot of details to consider beyond – rough estimate.

How To Roughly Determine What Size HVAC System Your Home Needs

To get a rough estimate of HVAC size, you’ll need to complete two basic steps:


Step One: Calculate Square Footage

Square footage is your home’s living space, or what you’ll want to be heated and cooled by your HVAC system.

You can find your home’s square footage in real estate or contractor paperwork from its purchase. If you’ve added additional living space since then or can’t find your paperwork, then you’ll need to measure the square footage.

Using a tape measure, determine the length and width of a room. Multiply the numbers together. Repeat the measuring for each space in your home. Don’t forget hallways and closets. Add all the numbers together for total square footage. Oddly shaped rooms can be a challenge, for instance, dividing triangle rooms by a factor of two and using pi for circular rooms.


Step Two: Calculate A Base BTU

British Thermal Unit (BTU) is the unit used to measure heating and cooling energy. Typical BTUs range from 5,000 to 34,000. So, it’s very important to get an approximation for your home’s specific needs.

Experts have determined that you need around 20 BTUs to heat and cool a single square foot. Knowing this, you can take your home’s total square footage and multiply it by 20. If your home is 1,500 square feet, for example, then you’d need around 30,000 BTUs.

To determine tonnage for the air conditioner, divide the BTU number by 12,000. So, a 1,500 square foot home would need a 2.5 tons unit.

Air conditioner professionals recommend going up a size (up to 15 percent over BTUs for cooling and 40 percent for heating) if your HVAC dealer doesn’t have the exact size you need or between common sizes. Since heat pumps handle both cooling and heating needs, you shouldn’t go over the BTUs by more than 25 percent.

The added power in these small increments will also ensure that your heating and cooling needs are met on extreme heat/cold days if your area is prone to them. Yet, the unit isn’t so big as to be a high cost and energy waste.


Other Considerations: Complete An Energy Audit

Unfortunately, square footage alone will not give you the most accurate picture of your HVAC needs. It offers a rough estimate that will point you in the right direction. Still, efficiency demands a complete energy audit of your home to know the exact sizing to accommodate your air condition and heating needs.

An energy audit looks at factors that influence a home’s heating and cooling abilities and demands, including:

  • Ductwork age, condition, and proper installation
  • Furnace efficiency rating
  • Climate zone
  • Number, style, and condition of windows and doors
  • Precise environment – shaded, sunny, windy, etc
  • Occupancy numbers
  • Appliance heat generation
  • Amount and quality of insulation
  • Ceiling height
  • Skylight presence
  • Crawl, attic, garage, and basement space
  • Lighting systems
  • Ventilation systems

Some of the above are obvious considerations, but the average homeowner may not realize all of these.

Occupancy is a good example. Most professionals add 600 BTUs per person if more than two people are occupying your home. People generate heat, and a larger unit is needed to properly heat and cool any space where multiple bodies coexist to emit body heat.

It’s a lot of complex considerations. HVAC dealers can perform an energy audit for you as part of their initial estimate for services. Some utility companies also provide free energy audits. Don’t skip this vital step in knowing exactly how many BTUs of heating and cooling is ideal for your unique home. Plus, it can help you identify any ways that your home is losing on energy performance.


Ready For Your HVAC?

In closing, this is one case where you certainly don’t want to put the horse before the cart. You can see just how important proper sizing is to your air conditioner functioning efficiently and having a long, healthy life.

Use square footage, BTUs per square foot, and general BTU guidelines to get a rough estimate on the unit size. Use a professional energy audit to fine-tune your home’s HVAC needs and identify areas of potential energy savings. Then, you can determine brand preferences based on consumer and expert recommendations.

Of course, all the steps for DIY rough estimates are included in professional estimates for HVAC installation. You can always contact your provider from the beginning to help you determine the sizing and find a heating and cooling solution that fits both your budget and home’s needs.

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