Tips for sizing HVAC unit

Published On: June 27, 20171 Comment on Tips for sizing HVAC unitTags: , Last Updated: February 13, 20242.7 min read

Heating, ventilation and air conditioning (HVAC) is one of the most complicated systems in a home. It consumes half of the entire energy in a household that’s why it only matters to size an air conditioner before buying one. Sizing refers to figuring out the system measurements you need to cool or heat your home accordingly. Contrary to myth, a bigger HVAC system is not always better. Do not allow a salesman to talk you into a larger unit. A system that is too large for your residential home will cost more money to operate. It will be inefficient because it will cycle on and off quickly. On the other hand, a unit that is too small will not properly cool and heat the space.
Tips for sizing HVAC unit

Follow these tips below to determine the right size for your residential home.

Ask an energy auditor to calculate the “Manual J.”
The Manual J calculation is the best way to size an HVAC unit. The Air Conditioning Contractors of America (ACCA) published software to accurately measure the total capacity of a unit. Calculating the Manual J involves a lot of factors, including the cubic footage of your home, its orientation to the sun, and the type of lighting you use. This includes the dehumidification capacity which many homeowners do not take into consideration. Determining how much heat you need is as important as how much cooling you need. A Fairbanks home, for instance, requires more heating than cooling because of the city’s very cold weather.
Calculate the “Manual D.”

This refers to calculating the ductwork size and design. The energy auditor will use the data from the Manual J to determine the Manual D. Having a wrong sized duct pushes out conditioned air and draws in unwanted air. This may increase your energy costs. Likewise, computing for the Manual D takes the time to understand. Hire an energy auditor to do the job accurately. There is no one-size-fits-all when it comes to HVAC units. Most HVAC contractors do not look at the quality of the distribution system, so get an energy auditor when sizing the system.

Get an accurate data for the “Manual S.”

The Manual S takes up where the Manual J left off. The latter only computes the heating and cooling loads. The Manual S takes a lot more factors into account. It identifies the correct heating and cooling equipment. That includes the health issues that may arise due to excessive humidity. A proper HVAC design is necessary for healthy indoor air quality.

Hire a reliable auditor to calculate the Manual J, Manual D, and Manual S. A properly sized HVAC system will run through the necessary amount of cycles to keep your home comfortable. It also uses minimal amount of energy. Aside from the sizing, it is also important to give your unit a basic maintenance. Your HVAC system needs annual tune-ups. Call a professional such as the Parker, CO HVAC professionals at 888 Heating and Cooling in case you noticed that something is wrong with your unit.

If you want to learn how to properly maintain your air conditioning system check out our article DIY air conditioner maintenance.

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  1. Zach November 14, 2017 at 5:20 am

    Great advise, I always try to remind people that a unit too large for the home will never stay on long enough to reach the optimum efficiency it was designed for, but people always think bigger is better!

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