Shopping for a new AC or furnace can be intimidating. If you want to find the best HVAC system for your home, it's natural to look for models with the highest efficiency ratings.
After all, the most efficient equipment provides the most comfort and lowest energy bills, right?
It’s not quite that simple.
Energy efficiency isn't the only thing you should consider 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 equally, if not more important for your home's comfort and your utility bills.
Proper sizing has a major impact on humidity control and system longevity. The best HVAC system for your home combines efficiency and proper sizing.
In this article, we'll explain what an air conditioner's SEER rating or SEER2 rating actually measures, why correct HVAC size is so important and why experienced HVAC professionals consider both when helping you select the best HVAC system for your home.
High Seer Ratings: What Do They Mean?
A SEER rating, (Seasonal Energy Efficiency Ratio), measures how effectively an AC cools your home over a standard cooling season. A SEER2 rating is the updated version of SEER, using test procedures that better represent real-world operating conditions. Nearly all new air conditioners have a SEER2 rating, simply because that is the current rating system for cooling equipment.
Fuel-burning heating system efficiency is evaluated by something called AFUE, which is for Annual Fuel Utilization Efficiency. Similar to SEER and SEER2, higher AFUE ratings indicate a high-efficiency HVAC system that uses less electricity to heat your home than lower-rated systems under standardized laboratory testing.
Even so, high numbers don't by themselves guarantee lower utility bills. Real-world heating and air conditioner efficiency depends on several key factors, including the installation quality, the condition of your ductwork, how much insulation your home has, thermostat settings and, most importantly, HVAC system sizing. Even the most efficient system cannot perform as intended if it is bigger than necessary or smaller than needed 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 new one the same size. In reality, new heating system installation or air conditioner replacement should be sized based on your home's true heating and cooling needs—not just square footage or the size of your existing equipment.
That's why reputable technicians complete 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 comfort needs, including:
- Home square footage
- Ceiling height
- Window size and placement
- Home insultation levels
- Air infiltration
- Area climate
- Number of occupants
- Heat generated by appliances and lighting
- Ductwork condition
A properly sized air conditioner runs long enough to cool your home more uniformly while pulling out excess humidity. That means more consistent temperatures, better indoor comfort and improved moisture control. It also helps the equipment to perform more effciently, reducing strain that can reduce its service life or lead to more repairs and higher repair costs.
When a furnace or AC is the right size for your home, you get greater comfort and more reliable operation.
Problems with Oversized and Undersized HVAC Equipment
It might be tempting to buy the most energy efficient, highest-capacity air conditioner or heating system on the market. In reality, that often isn't a good investment.
heating and cooling systems that are bigger than necessary or smaller than your home requires can create comfort issues, increase operating costs and reduce efficiency regardless of their SEER rating.
Common Problems With Oversized HVAC Systems
An oversized air conditioner or heating system may work quickly, but that doesn't mean it delivers the best comfort.
- Short cycling: An oversized HVAC system cycles repeatedly, reducing efficiency and increasing wear.
- Poor humidity removal: Oversized air conditioners cool your home too quickly to remove indoor humidity from the air.
- Uneven temperatures: Some rooms get too cold while others stay too warm.
- Increased wear and tear: Even though the system reaches the target temperature rapidly, those frequent starts and stops can cause avoidable breakdowns due to the strain.
Drawbacks of Undersized HVAC Systems
An undersized HVAC system also can struggle:
- Long run times: The system operates almost continuously trying to reach the set temperature, which also causes additional wear.
- Trouble reaching the thermostat setting: Your home may never feel as cool as you want during hot weather or feel too cool during winter.
- Increased energy consumption: Running almost constantly can increase utility bills.
- Added strain during extreme weather: HVAC systems that are too small can struggle in extreme temperatures, increasing wear and the likelihood of repairs.
Balancing 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 most efficient model on the market.
More often than not, a professionally sized, mid-efficiency heating and cooling system will provide better results than an overly large premium system because it runs the way it was designed to.
Thebest choice is an energy-efficient HVAC system that's correctly sized for your home, your budget, your climate and your long-term goals.
As you consider how to choose a new air conditioner or furnace, consider:
- Lower energy costs: Higher-efficiency and right-sized systems can reduce electricity use.
- Initial cost: High-efficiency AC and heating systems often have a higher purchase price than mid-range models but can lower long-term energy costs.
- Electricity rates: Areas with higher electricity rates may see better long-term savings from higher-efficiency units.
- Seasonal weather conditions: It's important your heating or cooling system has adequate capacity to handle areas with very cold winters or extremely hot summers.
- 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 justify the investment.
- Available rebates or tax incentives: Manufacturer promotions, {utility|equipment rebates and tax credits can lower the overall cost of higher-efficiency systems.
Real-World Example: High Seer vs. Right System Size
How does this work in a real world example?
Suppose there are two neighboring homes.
At the first home, the homeowner chooses a premium high-efficiency HVAC system that's too big because the contractor only matched the previous unit. Next door, the second homeowner installs a correctly sized, mid-efficiency system after completing a Manual J calculation.
Even though the second system has a more modest efficiency rating on paper, it may deliver lower operating costs, better home comfort, more effective humidity control and last longer because it's appropriately sized to the home's needs.
Choose the HVAC Professional Who Designs the Right Solution
An HVAC replacement should involve much more than selecting a system with the top efficiency rating. The right system is one that meets your heating and cooling requirements.
At Durable Service, our skilled HVAC experts perform an HVAC load calculation. We'll carefully evaluate your home's design, your household's comfort needs and recommend equipment that's properly matched for your home—not simply the biggest, most expensive unit or the one with the highest AFUE or SEER2 rating.
Our HVAC experts will connect you with any available rebates and tax incentives and provide information about HVAC financing options that make efficient heating and cooling systems more accessible for all budgets.
Schedule an HVAC consultation online with Durable Service now. We'll gladly evaluate your home, answer your questions and help you choose the right-sized energy-efficient system that keeps your family comfortable for years to come.
