Heating and cooling units come in a wide range of sizes, and ensuring you get the right-size unit for your home is essential. Installing a unit that’s the wrong size is a major waste of money, which is one of the reasons you should always hire a reputable, experienced HVAC contractor. In this article, we’ll explain why HVAC sizing is so important and also discuss what goes into determining what size of HVAC unit a home needs.
Energy Efficiency
All HVAC units are rated for energy efficiency, and these ratings are important when deciding which specific unit you want to install. By comparing energy-efficiency ratings, you can easily determine which unit offers the best value and will be most cost-effective overall. You can also use the ratings to estimate how much energy any unit you’re considering would likely use and, thus, how much you’d pay to use it to cool or heat your home.
The only issue is that the energy-efficiency rating of any HVAC unit is based on the unit being the proper size for the building. That means the rating will mostly be meaningless if you end up installing a unit that is too big or too small for your home. An undersized or oversized air conditioner, heat pump, or furnace will technically still work as efficiently as a properly sized unit. That said, a unit that is too big or too small will still end up using much more energy even if it works as efficiently as it’s supposed to.
The issue with an undersized unit is that it will cool or heat your home quite slowly. That means you’ll end up with the cooling or heating cycles being much longer than they normally should be, leading to higher electricity or gas bills.
An oversized unit will also make your cooling or heating costs quite a bit higher simply because its energy needs will always be higher compared to a smaller, correctly sized unit. Another issue with oversized units is that they typically short cycle. Short cycling is when a cooling or heating unit only runs for around 10 minutes or less before shutting off. The reason this happens is obviously that an oversized unit produces much more cooling or heating than what is actually needed. You may think having much shorter cooling or heating cycles is good, but it’s the opposite. The main issue with short cycling in terms of energy use is that it leads to the unit turning on and off more times a day than it should. This is especially an issue with air conditioners and heat pumps since they draw large amounts of power when turning on. In fact, the energy draw as the unit starts up is usually at least three to five times greater than when the unit is up and fully running.
Repair Requirements
Almost every HVAC unit will eventually develop some type of issue that prevents it from working as well and requires it to be repaired or have some component replaced. Nonetheless, it should come as no surprise that the harder a unit has to work and the more it runs, the greater the chance of it developing issues or completely breaking down. That’s why you can be almost certain that you’ll end up needing to have an undersized unit repaired more frequently than you would a unit that is the proper size for your house.
Oversized units will also almost always need more repairs over the course of their life. In this case, the unit will likely have major issues with short cycling and turning on and off more times per day. Short cycling leads to greatly increased wear and tear. This is because HVAC units are under much more strain when turning on than when fully running. That means the more cycles per day, the more issues it will likely develop over time.
Life Expectancy
The increased wear and tear that undersized and oversized HVAC units experience obviously has an impact on how long they may last before they need to be replaced. The typical life expectancy for furnaces and central air conditioners is around 15 years, but some units may last around 20 years. Heat pumps usually have a shorter lifespan since they provide both cooling and heating and thus run for many more hours each year. Some heat pumps will also end up lasting for 15 years, but many only last for 10-12 years. All of these numbers are merely averages and are based on the unit being the proper size. If the unit is undersized or oversized, it will likely give out at least a couple of years earlier.
Comfort Level
Having a properly sized HVAC unit is important for your comfort. Undersized cooling units are especially an issue in places like Texas that experience hot, humid summer weather. That’s because an undersized unit usually struggles to keep a home sufficiently cool. It may work well enough on cooler, less humid days, but it probably won’t be able to maintain your desired temperature the rest of the time.
No matter where you live, oversized cooling and heating units are also an issue. The fact that an oversized unit usually won’t run for very long means it may rarely or never sufficiently cool or heat every room in your home. As such, you’ll often end up dealing with hot or cold spots in different rooms. Another issue is that the temperature in your home will fluctuate between warmer and cooler more often than with a properly sized unit.
Installation Cost
This last factor applies specifically to oversized units. The larger an HVAC unit is, the more it will obviously cost. Depending on the type of unit you’re installing and how energy efficient it is, you could easily end up paying a few hundred or even a few thousand dollars more for an oversized unit compared to what you’d pay for a properly sized unit.
Factors That Affect What Size of HVAC Unit a Home Needs
You may think that it’s just the square footage of your home that determines what size of HVAC unit you need. The truth is that determining exactly what size of cooling or heating unit a home needs is quite a bit more complicated than most people realize. Numerous other factors need to be considered alongside the home’s square footage.
One of the biggest factors is location since homes in places like Texas obviously have higher cooling and lower heating requirements than in other parts of the country. There are some general recommendations as to how many BTUs of cooling and heating you need per square foot in different climate zones. However, these recommendations are based on the home having sufficient insulation and a fairly airtight external structure. A lack of insulation or lots of air leaks in the external structure means the requirements will be higher and necessitate a larger HVAC unit. Other factors HVAC technicians look at when sizing cooling or heating equipment include the number of windows and exterior doors, which direction most of the windows face, the number of occupants, and how much direct sunlight the house receives during the day.
Our Services
Accurate Home Services is a top-rated HVAC contractor that’s been serving Texas customers in Crandall, Kaufman, and the surrounding areas since 1992. When you choose us for your cooling or heating installation needs, you can rest assured that we’ll take the time to calculate exactly what size of HVAC unit your home needs. You can also count on us for your HVAC repair and maintenance needs or if you need any electrical or indoor air quality services. If you’re looking to install a new HVAC unit, contact us for expert advice and assistance.
