Choosing a new AC or furnace can be stressful. When you're looking to find the best HVAC system for your home, it's natural to look for models with extremely high efficiency ratings.
Surely the most efficient equipment should deliver the most comfort and lowest energy bills, right?
Actually, that’s not always the case.
Efficiency ratings aren’t the only thing that matters when it comes to new air conditioner installation or furnace replacement. Even though many 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 has a major impact on humidity control and system longevity. The best HVAC system for your home delivers 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 sizing is so important and why experienced HVAC professionals consider both when helping you select the best HVAC system for your home.
What Does it Mean if an AC Has a High SEER Rating?
A SEER rating, (Seasonal Energy Efficiency Ratio), measures how effectively an air conditioner cools your home over a normal cooling season. A SEER2 rating is the current version of SEER, using testing methods that better represent real-world operating conditions. Nearly all new air conditioners have a SEER2 designation, 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. Similar to SEER and SEER2, 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.
Even so, high numbers don't automatically guarantee lower utility bills. Actual heating and air conditioner efficiency depends on several key factors, including the way the system is installed, the state of your ductwork, insulation levels, thermostat settings and, most importantly, system sizing. Even the highest-efficiency system cannot deliver peak performance if it is too large or too small for the home.
Why HVAC System Size Matters More Than You Probably Think
Many assume a larger air conditioner or furnace will make their home the most comfortable or that they should simply replace their old HVAC system with a unit of the same capacity. In reality, new heating system installation or air conditioner replacement 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 conduct an HVAC load calculation, also called a Manual J calculation, before suggesting replacement equipment. A Manual J calculation considers many details that affect your home's heating and cooling requirements, including:
- Total square footage
- Room height
- Window size and placement
- Insulation
- Drafts and air leakage
- Area climate
- Household occupants
- Heat generated by appliances and lighting
- Air duct condition
A properly sized air conditioner runs through longer cooling cycles to cool your home more uniformly while pulling out excess humidity. That means steadier temperatures, better indoor comfort and improved moisture control. This also allows the equipment to operate more effciently, reducing unnecessary wear that can shorten its lifespan or lead to costly breakdowns.
When HVAC equipment is properly sized, you get improved comfort and long-lasting performance.
Problems with Oversized and Undersized Heating and Cooling Systems
It might be tempting to buy the most energy efficient, biggest air conditioner or heating system on the market. However, that's usually not a good investment.
HVAC systems that are bigger than necessary or too small can create comfort problems, increase energy expenses and reduce efficiency regardless of their SEER rating.
Common Problems With 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 starts and stops often, reducing efficiency and increasing equipment strain.
- Reduced humidity control: Oversized air conditioners cool your home too quickly to remove excess moisture from the air.
- Inconsistent temperatures: Some rooms become too cold while others aren’t ever cool enough.
- Additional equipment wear: Even though the system works quickly, those frequent starts and stops can cause avoidable breakdowns due to the strain.
Drawbacks of Undersized HVAC Systems
An undersized HVAC system has a different set of problems:
- Continuous operation: 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 feel cool enough during hot weather or feel too cool during winter.
- Increased energy consumption: Running nonstop can increase monthly energy expenses.
- Added strain during extreme weather: HVAC systems that are too small can run extremely hard in extreme temperatures, increasing equipment wear and the likelihood of repairs.
Finding the Right Balance Between Efficiency and Size
When trying to decide between a high SEER vs right-sized system, remember that you don't automatically need the most efficient model on the market.
Often, a properly sized, mid-efficiency heating and cooling 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 correctly sized for your home, your budget, your climate and your future plans.
As you think about how to choose a new air conditioner or furnace, consider:
- Efficiency savings: Higher-efficiency and right-sized systems can reduce 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.
- Electricity rates: Areas with more expensive electricity may see greater long-term savings from higher-efficiency units.
- Seasonal weather conditions: It's crucial your heating or cooling system has the right capacity to handle areas with extremely cold winters or very hot summers.
- Length of home ownership: 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 reduce the overall cost of high-efficiency HVAC equipment.
Real-World Comparison: High Seer vs. Right System Size
What does this look like in the real world?
Imagine 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 properly sized, mid-SEER or AFUE system after completing a Manual J calculation.
Although the second system has a lesser efficiency rating on paper, it may provide lower operating costs, better home comfort, improved humidity control and have a longer lifespan because it's properly matched to the home's needs.
Choose the Local HVAC Professional Who Designs Solutions Tailored to Your Home
Replacing your HVAC system should involve much more than selecting the unit with the top efficiency rating. An ideal system is one that meets your heating and cooling requirements.
At Thurston Heating & Air Conditioning, our skilled HVAC experts perform an HVAC load calculation. Our team will evaluate your home's layout and construction, your household's comfort goals 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 HVAC experts will connect you with 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 Thurston Heating & Air Conditioning to get started. Our team will evaluate your home, answer any questions and help you choose the properly sized efficient system that keeps your family comfortable for years to come.