What You Need to Know About Heater and Air Conditioner Sizing

If you have older heating or cooling units in your Crystal Lake, IL home, you likely have a comfort source that’s unreliable and less efficient than what’s available today. When you make the decision to replace your existing air conditioner or heater, the most important thing to do is get a size that’s appropriate for your home. Here’s a closer look at why HVAC sizing matters along with some tips to keep in mind.

air conditioning sizing

Air Conditioner Over-Sizing Is a Common Mistake

The most common sizing mistake is over-sizing. An air conditioner or heat pump, for instance, that’s sized too big for your home won’t run long enough to dehumidify the air. This could leave your home susceptible to mold growth. Over-sizing can also contribute to temperature swings throughout your home. Heater and AC sizing should take several factors into consideration, such as:

  • The type of windows in your home – and where they’re located
  • Your home’s level of insulation
  • Air infiltration
  • The local climate
  • Any steps you’ve taken to boost your home’s energy efficiency

Approved A/C Sizing Standards Matter

Homeowners are advised to work with contractors who use approved sizing standards, like the ones published by the Air Conditioning Contractors of America (ACCA) in their Manual J. Using approved standards helps maintain consistency and also provides certain guidelines contractors can use to give you a sizing estimate likely to be right for your needs.

What a ‘Good Estimator’ Does

Reliable contractors, like the ones from Official HVAC, will typically take the time to put the extra attention to detail into their size estimates. A good estimator is a contractor who takes steps such as:

  • Measuring floor space, walls, windows, and ceilings to get accurate room volume figures
  • Considering the R-value of your insulation, building materials, and windows
  • Doing a blower door test to measure air leakage
  • Examining your existing ductwork – e.g., its condition and whether or not joints are sealed
  • Checking the placement of supply/return registers

It can also be helpful for the orientation of your home to be considered. This is because heat loss can be affected by home much direct sun exposure your home gets. Furthermore, it’s important for a contractor to understand how their products remove humidity and take care of other important comfort processes. Boost your peace of mind a bit further by insisting on an agreement that includes:

  • The calculations (in writing) that were used to provide a size estimate
  • A list of the procedures and standards used to make a size estimate
  • A copy of calculations, assumptions, and other data that was used to recommend a size and offer an estimate of your final cost

Avoid These 4 Quick (But Often Inaccurate) Sizing Methods

Some HVAC contractors rely on “quickie” methods to provide size estimates for homeowners. While the four methods discussed below are fine for giving you a general idea of what to consider for your heating or cooling needs, they shouldn’t be used for your final sizing determination.

  1. A Quick ‘Guesstimate’
    Some contractors walk into your home and instantly recommend a unit that’s the same size or one that’s larger. However, this method doesn’t take factors discussed above into account.
  2. Sizing by Square Footage
    With this method, a contractor will give you a recommendation based solely on your home’s square footage. The problem here is that sizing done this way doesn’t consider things like:
    – The design of your home.
    – How you normally use your heating or cooling systems.
    – How energy efficient your home is.
  3. Contractor Estimates That Vary Greatly
    Sizing estimates from different contractors can vary greatly if different “rules of thumb” are used. Other times, contractors give size estimates based on what units they happen to have in stock at the moment – this may be cheaper for them, not you!
  4. Charts and Calculations
    The potential problem here is making math errors. You may also get figures that are too far off one way or the other.

If you live in the Crystal Lake, IL, area and you’re having trouble figuring out what type of heating or cooling solution is right for your needs and living spaces, Official HVAC is here to help. Contact us today to talk to one of our comfort pros.