Choosing a new AC or furnace can be stressful. If you want to find the best HVAC system for your home, it's common to look for models with extremely high efficiency ratings.
After all, the most efficient system provides the most comfort and lowest energy bills, right?
Not necessarily.
Efficiency ratings aren’t the only thing to think about when it comes to new air conditioner installation or installing a new furnace. Even though many focus only on efficiency ratings, proper HVAC system sizing is just as, if not more important for your home's comfort and your power bills.
Proper sizing has a major impact on humidity control and lasting performance. The best HVAC system for your home combines efficiency and proper 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 experienced HVAC professionals consider both when helping you select the best HVAC system for your home.
What Does a High SEER Rating Actually Mean?
A SEER rating, (Seasonal Energy Efficiency Ratio), indicates how efficiently a cooling system cools your home over a typical cooling season. A SEER2 rating is the newer version of SEER, using test procedures that better simulate real-world operating conditions. Nearly all new air conditioners have a SEER2 efficiency rating, simply because that is the current rating system for cooling equipment.
Fuel-burning heating system efficiency is evaluated by AFUE, which is short for Annual Fuel Utilization Efficiency. As with SEER and SEER2 ratings, higher AFUE ratings indicate a high-efficiency HVAC system that uses less electricity to keep you comfortable than lower-rated systems under standardized laboratory testing.
However, high ratings don't by themselves 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, how much insulation your home has, thermostat settings and, most importantly, proper HVAC system sizing. Even the highest-efficiency system cannot operate at its best if it is oversized or too small for the home.
Why Correct HVAC System Sizing Matters More Than Most Homeowners Realize
Many assume a higher-capacity air conditioner or furnace will make their home the most comfortable or that they should just replace their old HVAC system with a new one the same size. The truth is, new heating system installation or air conditioner replacement should be sized 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 technicians conduct an HVAC load calculation, also called a Manual J calculation, before recommending replacement equipment. A Manual J calculation considers many variables that impact your home's heating and cooling requirements, including:
- Total square footage
- Room height
- Window size and orientation
- Insulation
- Air infiltration
- Regional climate
- Number of occupants
- Heat produced from appliances and lighting
- Ductwork condition
A properly sized air conditioner runs for enough time to cool your home evenly while removing excess humidity. That means steadier temperatures, better indoor comfort and improved humidity control. Proper sizing also helps the equipment to run more effciently, reducing excessive wear and tear that can reduce its service life or lead to frequent or expensive repairs.
When a furnace or AC is correctly sized, you get greater comfort and long-lasting performance.
Problems Caused by Oversized and Undersized HVAC Equipment
Many homeowners are tempted to buy the most energy efficient, biggest air conditioner or heating system on the market. In reality, that often isn't a smart choice.
HVAC systems that are too large or smaller than your home requires can create indoor comfort challenges, increase operating costs and reduce efficiency regardless of their SEER rating.
Issues Created by Oversized HVAC Systems
An oversized air conditioner or heating system may reach the thermostat setting fast, but that doesn't mean it performs efficiently.
- Short cycling: An oversized HVAC system cycles repeatedly, reducing efficiency and increasing wear.
- Humidity problems: Oversized air conditioners reach the set temperature too fast to remove enough moisture from the air.
- Hot and cold spots: Some rooms become too cold while others stay too warm.
- Increased wear and tear: Even though the system works quickly, those repeated on-and-off cycles can cause avoidable breakdowns due to the strain.
Drawbacks of Undersized HVAC Systems
An undersized HVAC system also can struggle:
- Continuous operation: The system stays on for extended periods trying to reach the thermostat setting, which also causes additional wear.
- Difficulty reaching thermostat settings: Your home may never feel as cool as you want during hot weather or feel too cool during winter.
- Higher energy use: Running almost constantly can increase energy costs.
- Extra stress during severe weather: HVAC systems that are too small can work harder in extreme temperatures, increasing component strain and the chance of failure.
Why You Should Balance HVAC System Efficiency and Size
When weighing the pros and cons of a high SEER vs right-sized system, remember that you don't necessarily need the highest-efficiency model on the market.
Often, a properly sized, mid-efficiency HVAC system will provide better results than an oversized premium system because it operates 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 future plans.
When deciding how to choose a new air conditioner or furnace, keep these factors in mind:
- Lower energy costs: Higher-efficiency and right-sized systems can decrease electricity use.
- Purchase price: High-efficiency AC and heating systems often have a higher purchase price than mid-range models but can lower long-term energy costs.
- Energy prices: Areas with more expensive electricity may see greater long-term savings from higher-efficiency units.
- Climate: It's crucial your heating or cooling system has the right capacity to handle areas with harsh winter weather or extremely hot summers.
- Time you plan to own the home: If you expect to live in your home for many years, the long-term energy savings of a higher-efficiency unit may be worth the investment.
- Available rebates or tax incentives: Manufacturer promotions, {utility|equipment rebates and tax credits can lower the overall cost of qualifying equipment.
Real-World Situation: High Seer vs. Right System Size
How does this play out in a real world scenario?
Suppose there are two neighboring homes.
In one, the homeowner chooses a premium high-efficiency HVAC system that's too big 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, moderate-efficiency system after completing a Manual J calculation.
While the second system has a more modest 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 appropriately sized to the home's needs.
Work With an HVAC Professional Who Designs Solutions Tailored to Your Home
An HVAC replacement should involve much more than selecting the unit with the top efficiency rating. The right system is one that meets your heating and cooling requirements.
At Precision Mechanical, our experienced professionals perform an HVAC load calculation. We'll evaluate your home's layout and construction, your household's comfort goals and recommend equipment that's properly matched for your home—not simply the highest-capacity, fanciest unit or the one with the highest AFUE or SEER2 rating.
Our heating and cooling specialists will help you identify any available rebates or tax incentives and provide information about HVAC financing options that make high-efficiency systems more accessible for all budgets.
Schedule an HVAC consultation online with Precision Mechanical today. We'll evaluate your home, answer your questions and help you choose the right-sized energy-efficient system that keeps your family comfortable for many years.
