Shopping for a new air conditioning system 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.
Surely the most efficient equipment will provide the most comfort and lowest energy bills, right?
It’s not quite that simple.
High efficiency isn't the only thing that matters 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 equally, if not more important for your home's comfort and your energy bills.
Proper sizing directly impacts humidity control and system longevity. The best HVAC system for your home delivers energy efficiency and proper sizing.
In this blog, 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 a High SEER Rating Actually Mean?
A SEER rating, (Seasonal Energy Efficiency Ratio), measures how effectively an AC cools your home over a normal cooling season. A SEER2 rating is the updated version of SEER, using evaluation methods that better represent 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 evaluated by something called AFUE, 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 heat your home than lower-rated systems under standardized laboratory testing.
However, high numbers don't necessarily guarantee lower utility bills. Actual heating and air conditioner efficiency depends on many factors, including the quality of the installation, the condition of your ductwork, insulation levels, thermostat settings and, most importantly, proper HVAC system sizing. Even the highest-efficiency system cannot deliver peak performance if it is oversized or smaller than needed 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 just replace their old HVAC system with a unit of the same capacity. In reality, new heating system installation or AC replacement should be chosen 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 evaluates many variables that impact your home's heating and cooling requirements, including:
- Total square footage
- Ceiling height
- Window size and direction
- Insulation
- Air leakage
- Regional climate
- Number of occupants
- Heat generated by appliances and lighting
- Air duct condition
A properly sized air conditioner runs long enough to cool your home evenly while eliminating excess humidity. That means more even temperatures, better indoor comfort and improved moisture control. It also helps the equipment to perform 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 properly sized, you get better comfort and long-lasting performance.
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. However, that’s rarely a great idea.
heating and cooling systems that are bigger than your home needs or undersized can create comfort issues, 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 works well.
- Short cycling: An oversized HVAC system turns on and off frequently, reducing efficiency and increasing wear and tear.
- Reduced humidity control: Oversized air conditioners cool your home too quickly to remove indoor humidity from the air.
- Uneven temperatures: Some rooms feel too cool while others stay too warm.
- Increased wear and tear: Even though the system heats or cools your home fast, those frequent starts and stops can cause avoidable breakdowns due to the strain.
Drawbacks of Undersized HVAC Systems
An undersized HVAC system can have the opposite problem:
- Long run times: The system operates almost continuously trying to reach the desired temperature, which also causes additional wear.
- Difficulty reaching thermostat settings: Your home may never feel as cool as you want during hot weather or always feel chilly in the winter.
- Increased energy consumption: Running almost constantly can increase energy costs.
- Added strain during extreme weather: HVAC systems that are too small can run extremely hard in extreme temperatures, increasing 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 necessarily need the most efficient model on the market.
In many cases, a correctly sized, mid-efficiency heating and cooling system will outperform an oversized premium system because it runs the way it was designed to.
Thesmartest choice is an energy-efficient HVAC system that's matched for your home, your budget, your climate and your long-term needs.
As you consider how to choose a new air conditioner or furnace, keep these factors in mind:
- Efficiency savings: Higher-efficiency and right-sized systems can decrease electricity use.
- Upfront investment: High-efficiency AC and heating systems often cost more initially than mid-range models but can reduce long-term energy costs.
- Local utility costs: Areas with higher utility costs may see more significant long-term savings from higher-efficiency units.
- Your local climate: It's essential your heating or cooling system has enough capacity to handle areas with very cold winters or intense summer heat.
- How long you'll 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 lower the overall cost of qualifying equipment.
Real-World Comparison: High Seer vs. Right System Size
How does this play out in a real world example?
Imagine two neighboring homes.
At the first home, the homeowner chooses a premium high-efficiency HVAC system that's too big for the house because the contractor only matched the previous unit. At the neighboring home, an HVAC professional installs a right-sized, mid-SEER or AFUE 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, more effective humidity control and have a longer lifespan because it's appropriately sized to the home's needs.
Choose the Local HVAC Professional Who Designs Personalized Solutions
HVAC replacent or installation should involve much more than selecting a system with the top efficiency rating. The best system is one that meets your household heating and cooling requirements.
At Mayeuxs AC & Heating, our skilled HVAC experts perform an HVAC load calculation. Our team will evaluate your home's design, your household's comfort needs and recommend equipment that's right for your home—not simply the largest, most expensive unit or the one with the highest AFUE or SEER2 rating.
Our heating and cooling specialists 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 Mayeuxs AC & Heating now. We'll evaluate your home, answer any questions and help you choose the properly sized energy-efficient system that keeps your family comfortable for the long haul.
