Shopping for a new air conditioner or furnace can feel overwhelming. If you're trying to find the best HVAC system for your home, it's understandable to look for models with the highest efficiency ratings.
After all, the most efficient system will provide the most comfort and lowest energy bills, right?
It’s not quite that simple.
Energy efficiency isn't the only thing that matters when it comes to new air conditioner installation or replacing your furnace. Although many people focus only on energy efficiency, proper HVAC system sizing is often even more important for your home's comfort and your utility bills.
Proper sizing also influences humidity control and system longevity. The best HVAC system for your home combines energy efficiency and correct 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 qualified HVAC contractors consider both when helping you choose the best HVAC system for your home.
What Does a High SEER Rating Actually Mean?
A SEER rating, (Seasonal Energy Efficiency Ratio), indicates how effectively an air conditioner cools your home over a standard cooling season. A SEER2 rating is the current version of SEER, using evaluation methods that better reflect real-world operating conditions. Today’s new air conditioners have a SEER2 designation, simply because that is the new rating system for cooling equipment.
Fuel-burning heating system efficiency is measured by 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 keep you comfortable than lower-rated systems under standardized laboratory testing.
Even so, high ratings don't by themselves guarantee lower utility bills. Real-world heating and air conditioner efficiency depends on more than just efficiency ratings, including the way the system is installed, the quality of your ductwork, how much insulation your home has, thermostat settings and, most importantly, HVAC system sizing. Even the most efficient system cannot operate at its best if it is too large or too small for the home.
Why Correct HVAC System Sizing Matters More Than You Think
Many assume a higher-capacity air conditioner or furnace will heat or cool a home better or that they should just replace their old HVAC system with a new one the same size. Actually, new heating system installation or AC replacement should be sized based on your home's actual heating and cooling needs—not just square footage or the capacity of the old system.
That's why reputable companies complete an HVAC load calculation, also called a Manual J calculation, before suggesting replacement equipment. A Manual J calculation analyzes many variables that impact your home's heating and cooling requirements, including:
- Overall 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 for enough time to cool your home more uniformly while pulling out excess humidity. That means steadier temperatures, better indoor comfort and improved indoor humidity management. This also allows the equipment to operate more effciently, reducing unnecessary wear that can shorten its lifespan or lead to costly breakdowns.
When a furnace or AC is correctly sized, you get better comfort and more reliable operation.
Problems Caused by Oversized and Undersized HVAC Equipment
It might be tempting to buy the most energy efficient, biggest air conditioner or heating system on the market. The truth is, that's usually not a good investment.
HVAC systems that are bigger than your home needs or smaller than your home requires can create comfort problems, increase utility costs 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 performs efficiently.
- Short cycling: An oversized HVAC system starts and stops often, reducing efficiency and increasing wear and tear.
- High indoor humidity: Oversized air conditioners reach the set temperature too fast to remove enough moisture from the air.
- Uneven temperatures: Some rooms feel too cool while others aren’t ever cool enough.
- More wear and tear: Even though the system works quickly, those constant cycles can cause avoidable breakdowns due to the strain.
Issues Created by Undersized HVAC Systems
An undersized HVAC system can have the opposite problem:
- Continuous operation: The system operates almost continuously trying to reach the desired temperature, 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.
- Extra stress during severe weather: HVAC systems that are too small can run extremely hard in extreme temperatures, increasing component strain and the likelihood of repairs.
Finding the Right Balance Between Efficiency and Size
When weighing the pros and cons of a high SEER vs right-sized system, don't forget that you don't automatically need the top-efficiency model on the market.
In many cases, a correctly sized, mid-efficiency HVAC system will provide better results than an oversized premium system because it runs the way it was designed to.
Theideal choice is an energy-efficient HVAC system that's properly 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, keep these factors in mind:
- Efficiency savings: Higher-efficiency and right-sized systems can lower electricity use.
- Initial cost: High-efficiency AC and heating systems often have a higher purchase price than mid-range models but can reduce long-term energy costs.
- Electricity rates: Areas with higher electricity rates may see better long-term savings from higher-efficiency units.
- Climate: It's essential your heating or cooling system has the right capacity to handle areas with extremely cold winters or extremely hot summers.
- 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 justify the investment.
- Rebates and tax credits: Manufacturer promotions, {utility|equipment rebates and tax credits can lower the overall cost of higher-efficiency systems.
Real-World Situation: High Seer vs. Right System Size
How does this work in the real world?
Picture two neighboring homes.
In one, the homeowner chooses a premium high-efficiency HVAC system has far more capacity than the home needs 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.
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 the Right Solution
Replacing your HVAC system should involve more than selecting a model with the top efficiency rating. An ideal system is one that meets your heating and cooling requirements.
At Prudhom Mechanical, our experienced professionals perform an HVAC load calculation. We'll carefully evaluate your home's design, your household's comfort goals and recommend equipment that's right for your home—not simply the biggest, most expensive unit or the one with the highest AFUE or SEER2 rating.
Our team 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 Prudhom Mechanical to get started. Our team will evaluate your home, answer any questions and help you choose the properly sized high-efficiency system that keeps your family comfortable for many years.