Choosing a new air conditioning system or furnace can feel overwhelming. If you're trying to find the best HVAC system for your home, it's common to focus on models with the highest efficiency ratings.
Surely the most efficient system should deliver the most comfort and lowest energy bills, right?
Not necessarily.
Efficiency ratings aren’t the only thing you should consider when it comes to new air conditioner installation or furnace replacement. Although many people focus only on energy efficiency, proper HVAC system sizing is equally, if not more important for your home's comfort and your energy bills.
Proper sizing has a major impact on humidity control and system longevity. The best HVAC system for your home delivers efficiency and correct sizing.
In this guide, we'll explain what an air conditioner's SEER rating or SEER2 rating actually measures, why proper HVAC system size is so important and why trusted HVAC experts consider both when recommending the best HVAC system for your home.
High Seer Ratings: What Do They Mean?
A SEER rating, (Seasonal Energy Efficiency Ratio), measures how efficiently a cooling system cools your home over a standard cooling season. A SEER2 rating is the updated version of SEER, using test procedures that better reflect real-world operating conditions. Today’s new air conditioners have a SEER2 efficiency rating, simply because that is the updated rating system for cooling equipment.
Fuel-burning heating system efficiency is rated by an AFUE rating, which stands for Annual Fuel Utilization Efficiency. As with SEER and SEER2, higher AFUE ratings indicate a high-efficiency HVAC system that uses less electricity to achieve indoor comfort than lower-rated systems under standardized laboratory testing.
That said, high ratings don't automatically guarantee lower utility bills. Everyday heating and air conditioner efficiency depends on several key factors, including the quality of the installation, the state of your ductwork, your home's insulation, thermostat settings and, most importantly, proper HVAC system sizing. Even the highest-efficiency system cannot perform as intended if it is too large or undersized for the home.
Why Correct HVAC System Sizing Matters More Than You Probably Think
Many assume a bigger air conditioner or furnace will make their home the most comfortable or that they should just replace their old HVAC system with a unit of the same capacity. The truth is, new heating system installation or air conditioner replacement should be selected based on your home's actual heating and cooling needs—not just square footage or the size of your existing equipment.
That's why reputable contractors conduct an HVAC load calculation, also called a Manual J calculation, before suggesting replacement equipment. A Manual J calculation considers many variables that affect your home's comfort needs, including:
- Total square footage
- Room height
- Window size and orientation
- Home insultation levels
- Air leakage
- Local climate
- Number of occupants
- Heat produced from appliances and lighting
- Air duct condition
A properly sized air conditioner runs through longer cooling cycles to cool your home consistently while pulling out excess humidity. That means more even temperatures, better indoor comfort and improved moisture control. It also helps the equipment to operate more effciently, reducing excessive wear and tear that can shorten its lifespan or lead to frequent or expensive repairs.
When HVAC equipment is correctly sized, you get improved comfort and more dependable performance.
Problems Caused by Oversized and Undersized Systems
It might be tempting to buy the most energy efficient, highest-capacity air conditioner or heating system on the market. The truth is, that’s rarely a smart choice.
HVAC systems that are bigger than your home needs or smaller than your home requires can create comfort issues, increase operating costs and reduce efficiency regardless of their SEER rating.
Drawbacks of Oversized HVAC Systems
An oversized air conditioner or heating system may heat or cool rapidly, but that doesn't mean it delivers the best comfort.
- Short cycling: An oversized HVAC system turns on and off frequently, reducing efficiency and increasing wear and tear.
- Reduced humidity control: Oversized air conditioners reach the set temperature too fast to remove indoor humidity from the air.
- Uneven temperatures: Some rooms feel too cool while others never feel comfortable.
- Additional equipment wear: Even though the system heats or cools your home fast, those frequent starts and stops can cause avoidable breakdowns due to the strain.
Issues Created by Undersized HVAC Systems
An undersized HVAC system can have the opposite problem:
- Long run times: The system stays on for extended periods trying to reach the thermostat setting, which also causes additional wear.
- Difficulty maintaining the desired temperature: Your home may never feel as cool as you want during hot weather or feel too cool during winter.
- Higher energy use: Running for extended periods can increase energy costs.
- Extra stress during severe weather: HVAC systems that are too small can work harder in extreme temperatures, increasing wear and the risk of breakdowns.
Balancing Efficiency and Size
When trying to decide between a high SEER vs right-sized system, keep in mind that you don't always need the highest-efficiency model on the market.
Often, a correctly sized, mid-efficiency HVAC system will outperform an oversized premium system because it functions the way it was designed to.
Theideal choice is an energy-efficient HVAC system that's matched for your home, your budget, your climate and your long-term goals.
When deciding how to choose a new air conditioner or furnace, think about:
- Lower energy costs: Higher-efficiency and right-sized systems can decrease electricity use.
- Initial cost: High-efficiency AC and heating systems often require a larger upfront investment than mid-range models but can reduce long-term energy costs.
- Energy prices: Areas with higher utility costs may see more significant long-term savings from higher-efficiency units.
- Climate: It's important your heating or cooling system has adequate capacity to handle areas with very cold winters or intense summer heat.
- Time you plan to own the home: If you intend to remain in your home for many years, the long-term energy savings of a higher-efficiency unit may be worth the investment.
- Rebates and tax credits: Manufacturer promotions, {utility|equipment rebates and tax credits can reduce the overall cost of high-efficiency HVAC equipment.
Real-World Example: High Seer vs. Right System Size
How does this work in the real world?
Picture two neighboring homes.
At the first home, the homeowner chooses a premium high-efficiency HVAC system has far more capacity than the home needs because the contractor replaced it with the same size system as the previous unit. At the neighboring home, an HVAC professional installs a correctly sized, mid-efficiency system after completing a Manual J calculation.
While the second system has a lesser efficiency rating on paper, it may provide lower operating costs, better home comfort, more effective humidity control and have a longer lifespan because it's correctly matched to the home's needs.
Choose the Local HVAC Professional Who Designs Solutions Tailored to Your Home
An HVAC replacement should involve much more than selecting a model with the top efficiency rating. An ideal system is one that meets your heating and cooling requirements.
At May's Heating & Air, our skilled HVAC experts perform an HVAC load calculation. We'll evaluate your home's design, your household's comfort goals and recommend equipment that's designed specifically for your home—not simply the largest, fanciest unit or the one with the highest AFUE or SEER2 rating.
Our team will help you identify any available rebates or tax incentives and provide information about HVAC financing options that make energy-efficient HVAC systems more accessible for all budgets.
Schedule an HVAC consultation online with May's Heating & Air today. Our team will evaluate your home, answer your questions and help you choose the properly sized efficient system that keeps your family comfortable for many years.