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Understanding HVAC: Load Calculation

If you’ve ever needed a new air conditioning system for your home, you’ve probably heard about finding the perfect AC unit for your home’s needs. But what exactly does this mean? When an HVAC professional is “sizing up” your home, they mean that literally. They’re referring to an HVAC load calculation, one of the most important steps in optimizing your space for staying comfortable.

HVAC load calculations often sound complicated, especially if you aren’t familiar with the process. But that’s why we’re here to break down what how these calculations work, why they’re so important, and how you can find the right heating and AC system or your own home!

Row of ac units

How We Calculate Your HVAC Load

There are dozens of reputable, reliable companies for heating and cooling needs. When you’re getting a new system, you’ll definitely want to work with a local expert! A professional company will walk you through the process of picking the perfect system for your home. And one of the main steps is determining your AC and heating needs throughout the year.

What is an HVAC load? Your HVAC load is how much work your system has to do to maintain a comfortable temperature inside your home. A big home with tall ceilings in a cold environment will need different specifications, functions, and power than a small Florida home that fights the heat all year long. Climate, space, and the number of people residing in the house are just a few factors that effect the result.

Calculating BTUs with the Manual J

There are two ways that HVAC companies determine residential load. The first way is with the Manual J from the Air Conditioning Contractors of America. This is a long, complicated formula that figures out the exact number of BTUs (British Thermal Units) that will be required to heat and cool your space. This is a formula designed for residential spaces, and companies will use the Manual N for commercial calculations.

This formula includes all different aspects of the house, including:

Formula Factors for BTU Calculations:

  • Climate
  • Insulation
  • Space
  • Windows & Doors
  • Ductwork Leakage
  • Wall Locations
  • And More!

However, such a complex formula is not necessary for every load calculation. And that’s why companies have developed a secondary approach to sizing your AC system.

There’s Gotta Be a Better Way (to Find BTUs)

It would be expensive to use the Manual J calculation every time a company goes out for a consultation. That’s why most HVAC experts will do an approximate estimate for homeowners instead. This process takes into account the square footage of the house, the insulation factors, and the heat-producing appliances. And in the end, you’ll have a rough idea of what kind of AC unit you’re looking at for properly heating and cooling your house.

Why Does It Matter?

changing thermometer
Keeping Cool is About More than the Number on the Thermostat

Your home’s AC and heating is about way more than just comfort. A poorly-sized unit impacts your ability to enjoy a cool summer afternoon or a cozy winter night – but it also means higher energy bills and more repair costs.

What does it mean when your system is undersized? It means that the air conditioner or heater just can’t perform when it needs to. It works harder and longer to keep up with changing weather. Running more frequently (and working harder) will raise your power bills on hot or cold days, and it will also wear down your system faster. You’ll be looking at high maintenance costs, frequent repairs, and a shorter lifespan for your HVAC system.

You’ll also have similar problems for different reasons with an oversized system. When your HVAC unit is too big, it short-cycled – meaning that it runs and then reaches the proper temperature too soon, cutting off before the cycle completes. This is inefficient and can even cause damage to your AC over time. You’ll see your system turning on and off frequently as it tries to maintain the temperature in your space.

Are you running into high energy bills, bad temperature control, short-cycling, or frequent repairs? Then you might have an HVAC system that’s too big or too small for your space! Talk to your local heating and cooling experts at Bates Air and Heat, and find out what we can do to minimize your repairs or replace your system with one suited for your needs. We service all of Vero Beach, FL and the surrounding areas, so give us a call and find out how we can help you stay comfortable all year long!

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