Choosing a new air conditioning system or furnace can be intimidating. When you're looking to find the best HVAC system for your home, it's understandable to focus on models with the highest efficiency ratings.
Surely the most efficient heating and cooling system should deliver the most comfort and lowest energy bills, right?
Not necessarily.
High efficiency isn't the only thing that matters when it comes to new air conditioner installation or replacing your furnace. While many homeowners focus only on energy efficiency, proper HVAC system sizing is just as, if not more important for your home's comfort and your energy bills.
Proper sizing also influences humidity control and long-term reliability. The best HVAC system for your home balances energy efficiency and proper sizing.
In this guide, we'll explain what an air conditioner's SEER rating or SEER2 rating actually measures, why correct HVAC size is so important and why qualified HVAC contractors consider both when helping you choose the best HVAC system for your home.
High Seer Ratings: What Do They Mean?
A SEER rating, (Seasonal Energy Efficiency Ratio), shows how effectively an AC cools your home over a standard cooling season. A SEER2 rating is the updated version of SEER, using testing methods that better simulate real-world operating conditions. Most new air conditioners have a SEER2 designation, simply because this is the current rating system for cooling equipment.
Fuel-burning heating system efficiency is measured by an AFUE rating, which stands for Annual Fuel Utilization Efficiency. Like 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.
Even so, high numbers don't necessarily guarantee lower utility bills. Real-world heating and air conditioner efficiency depends on several key factors, including the quality of the installation, the quality of your ductwork, insulation levels, thermostat settings and, most importantly, HVAC system sizing. Even the most efficient system cannot perform as intended if it is bigger than necessary or undersized for the home.
Why HVAC System Size Matters More Than You Probably Think
Many assume a bigger air conditioner or furnace will work the best or that they should simply replace their old HVAC system with a unit of the same capacity. Actually, new heating system installation or a new air conditioner should be chosen based on your home's current heating and cooling needs—not just square footage or the capacity of the old system.
That's why reputable technicians perform an HVAC load calculation, also called a Manual J calculation, before selecting replacement equipment. A Manual J calculation evaluates many details that affect your home's heating and cooling load, including:
- Overall square footage
- Room height
- Window size and direction
- Insulation
- Air leakage
- Local climate
- Number of occupants
- Heat generated by appliances and lighting
- Ductwork condition
A properly sized air conditioner runs long enough to cool your home consistently while pulling out excess humidity. That means more consistent temperatures, better indoor comfort and improved moisture control. It also helps the equipment to operate more effciently, reducing strain that can cause it to wear it out sooner or lead to more repairs and higher repair costs.
When a furnace or AC is properly sized, you get greater comfort and more dependable performance.
Problems Caused by Oversized and Undersized Heating and Cooling Systems
Many homeowners are tempted to buy the most energy efficient, largest-capacity air conditioner or heating system on the market. In reality, that’s rarely a great idea.
heating and cooling systems that are bigger than your home needs or too small can create comfort issues, increase energy expenses and reduce efficiency regardless of their SEER rating.
Drawbacks of Oversized HVAC Systems
An oversized air conditioner or heating system may reach the thermostat setting fast, but that doesn't mean it delivers the best comfort.
- Short cycling: An oversized HVAC system cycles repeatedly, reducing efficiency and increasing wear and tear.
- Humidity problems: Oversized air conditioners reach the set temperature too fast to remove indoor humidity from the air.
- Hot and cold spots: Some rooms get too cold while others never feel comfortable.
- More wear and tear: Even though the system works quickly, those frequent starts and stops can cause avoidable breakdowns due to the strain.
Issues Created by Undersized HVAC Systems
An undersized HVAC system also can struggle:
- Long run times: The system operates almost continuously trying to reach the thermostat setting, which also causes unnecessary wear and tear.
- Trouble reaching the thermostat setting: Your home may not feel comfortable during hot weather or always feel chilly in the winter.
- Higher energy use: Running almost constantly can increase monthly energy expenses.
- Added strain during extreme weather: HVAC systems that are too small can struggle in extreme temperatures, increasing equipment wear and the chance of failure.
Finding the Right Balance Between Efficiency and Size
When weighing the pros and cons of a high SEER vs right-sized system, remember that you don't automatically need the top-efficiency model on the market.
Often, a professionally sized, mid-efficiency heating and cooling system will deliver better performance than an overly large premium system because it operates the way it was designed to.
Theideal choice is an energy-efficient HVAC system that's correctly sized for your home, your budget, your climate and your long-term needs.
When deciding how to choose a new air conditioner or furnace, consider:
- Energy savings: Higher-efficiency and right-sized systems can decrease electricity use.
- Upfront investment: High-efficiency AC and heating systems often require a larger upfront investment than mid-range models but can lower long-term energy costs.
- Electricity rates: Areas with higher utility costs may see greater long-term savings from higher-efficiency units.
- Climate: It's crucial your heating or cooling system has adequate capacity to handle areas with extremely cold winters or very hot summers.
- Length of home ownership: If you intend to remain in your home for many years, the long-term energy savings of a higher-efficiency unit may offset the investment.
- Available rebates or tax incentives: Manufacturer promotions, {utility|equipment rebates and tax credits can reduce the overall cost of high-efficiency HVAC equipment.
Real-World Situation: High Seer vs. Right System Size
How does this work in a real world example?
Picture 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. The other homeowner installs a right-sized, moderate-efficiency system after completing a Manual J calculation.
Even though the second system has a lesser efficiency rating on paper, it may provide lower operating costs, better home comfort, improved humidity control and last longer because it's appropriately sized to the home's needs.
Choose the HVAC Professional Who Designs Solutions Tailored to Your Home
An HVAC replacement should involve more than selecting a system with the highest efficiency rating. An ideal system is one that meets your heating and cooling requirements.
At Aggressive Mechanical, our knowledgeable technicians perform an HVAC load calculation. We'll carefully evaluate your home's size and layout, your household's heating and cooling preferences and recommend equipment that's designed specifically for your home—not simply the largest, most expensive unit or the one with the highest AFUE or SEER2 rating.
Our team will let you know about 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 Aggressive Mechanical to get started. We'll gladly evaluate your home, answer any questions and help you choose the right-sized efficient system that keeps your family comfortable for years to come.