The Benefits of Heat Load Testing Your HVAC System

The heating and cooling loads of a space describe the amount of energy required to maintain a comfortable temperature. When you don’t perform heat load testing, you risk buying the wrong size air conditioner. This post explains the benefits of performing heat load calculations.

Why Is Heat Load Testing Important?

Simply put, heat load testing ensures your AC unit keeps your home at a comfortable temperature while maximizing energy efficiency.

When performed during the construction phase of a home, HVAC load calculations inform every aspect of your system, from AC size to the ductwork. However, most builders don’t perform actual load calculations; they simply use rule of thumb guidelines based on square footage. (Typically, this is 1 ton – or 12,000 BTUs – for every 400 square feet.) Unfortunately, square footage is only one part of the calculation. Other factors to consider include:

  • The direction the home faces
  • Number, placement, and types of windows
  • Other surfaces that gain or lose heat
  • Local climate
  • Insulation levels in walls, floors, and ceilings
  • How many people live in the home

Failure to perform heat load testing usually results in the contractor installing the wrong size air conditioner. And whether it’s too large or too small, the wrong sized AC unit is going to cost you more.

Too hot and too cold concept

What Happens When Your Air Conditioner Is Too Small?

When your air conditioner is too small, it has to work much harder to maintain the right temperature in your home. During the height of summer, this means your AC seems to run pretty much round-the-clock without ever truly cooling your home.

The result of those long cycles is sky rocketing power bills. Those long run times also place enormous strain on your HVAC system, seriously impacting its lifespan.

Can Your Air Conditioner Be Too Big?

We know that “bigger is better” is a common mantra. However, when it comes to your air conditioner, too big isn’t any better than too small.

Like most products, air conditioners are designed to operate in ideal conditions. This means they’re built to run for a certain amount of time in order to attain the proper temperature. When the unit is too large, it does something called short cycling. That’s because it doesn’t need to run as long as it was designed to in order to cool the space. Short cycling leads to energy inefficiency similar to what you experience when driving your car during stop-and-go traffic versus driving at a steady speed on the highway.

Short cycling also shortens the lifespan of your unit, because it turns on and off more frequently. And, it often leads to a house that feels “clammy” because the unit doesn’t run long enough to dehumidify the air. Finally, of course, up-front costs are higher for a larger air conditioner as well.

What Is the Peak Heating Load?

The peak heat load tells you how much heat your home loses due to both interior and exterior design factors. This includes heat lost through:

  • Exposed walls
  • Roof and ceiling
  • Windows, doors, and cracks
  • Flooring and foundation
  • Attic and basement walls and floors

It also considers cold air gained through openings like windows, doors, and cracks.

Heating and cooling are just right

What Is the Peak Cooling Load?

The peak cooling load describes how much heat your home gains due to design and environment. It is essentially the same as the peak heating load, but it measures ways that cooled air leaves your home as well as how hot air enters it.

Where peak cooling load differs, though, is in its consideration of times of day during midsummer. This is where your home’s orientation (the direction it faces) and windows play a large role in determining peak cooling load. That’s because solar gain (i.e. heat from the sun) can be substantial, even during early morning hours, for east-facing windows.

To determine the whole home’s cooling needs during the peak summer months, calculations must include peak numbers for each room.

Choosing the Right Sized Air Conditioner

Whether you’re buying a unit for a new home or replacing your old air conditioner, it’s important to buy the right sized system. You also want an AC with a SEER rating that helps save energy while still cooling your home.

An experienced HVAC installer is your best resource here. We can perform the heat load calculations necessary to determine the ideal unit for maximum efficiency and cooling. To learn more about Northern Air or request a free quote, just call us at 480.352.8710. Or, you can fill out our contact form and we’ll get back to you as soon as possible.


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