Shopping for a new air conditioning system 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 extremely high efficiency ratings.
Surely the most efficient equipment will provide the most comfort and lowest energy bills, right?
Actually, that’s not always the case.
High efficiency isn't the only thing you should consider 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 energy bills.
Proper sizing has a major impact on humidity control and lasting performance. The best HVAC system for your home combines energy 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 size is so important and why qualified HVAC contractors consider both when recommending the best HVAC system for your home.
What Does a High SEER Rating Actually Mean?
A SEER rating, (Seasonal Energy Efficiency Ratio), shows how efficiently an AC cools your home over a normal cooling season. A SEER2 rating is the current version of SEER, using testing methods that better reflect real-world operating conditions. Most new air conditioners have a SEER2 designation, simply because this rating is the new rating system for cooling equipment.
Fuel-burning heating system efficiency is evaluated by 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 keep you comfortable than lower-rated systems under standardized laboratory testing.
That said, high numbers don't automatically guarantee lower utility bills. Real-world heating and air conditioner efficiency depends on many factors, including the installation quality, the state of your ductwork, insulation levels, thermostat settings and, most importantly, proper HVAC system sizing. Even the highest-rated system cannot perform as intended if it is oversized or smaller than needed for the home.
Why Correct HVAC System Sizing Matters More Than You Think
Many assume a larger air conditioner or furnace will work the best or that they should just 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 current 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 analyzes many details that affect your home's heating and cooling load, including:
- Total square footage
- Room height
- Window size and orientation
- Insulation
- 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 removing excess humidity. That means more consistent temperatures, better indoor comfort and improved humidity control. It also helps the equipment to perform more effciently, reducing unnecessary wear that can shorten its lifespan or lead to costly breakdowns.
When your heating or cooling system is correctly sized, you get better comfort and more dependable 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. In reality, that's usually not a smart choice.
HVAC systems that are too large or undersized can create comfort problems, increase utility costs and reduce efficiency regardless of their SEER rating.
Issues Created by 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.
- High indoor humidity: Oversized air conditioners cool your home too quickly to remove enough moisture from the air.
- Hot and cold spots: Some rooms get too cold while others stay too warm.
- Additional equipment wear: Even though the system reaches the target temperature rapidly, those constant cycles can cause avoidable breakdowns due to the strain.
Cons Associated with Undersized HVAC Systems
An undersized HVAC system has a different set of problems:
- Long run times: The system stays on for extended periods trying to reach the set temperature, which also causes extra strain.
- Trouble reaching the thermostat setting: Your home may feel cool enough during hot weather or feel too cool during winter.
- Higher energy use: 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 wear and the likelihood of repairs.
Balancing Efficiency and Size
When weighing the pros and cons of a high SEER vs right-sized system, don't forget that you don't necessarily need the top-efficiency model on the market.
Often, a properly sized, mid-efficiency HVAC system will provide better results than an overly large premium system because it runs 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.
As you consider how to choose a new air conditioner or furnace, keep these factors in mind:
- Energy 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 help reduce long-term energy costs.
- Electricity rates: Areas with higher electricity rates may see greater long-term savings from higher-efficiency units.
- Your local climate: It's crucial your heating or cooling system has adequate capacity to handle areas with harsh winter weather 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 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 Situation: High Seer vs. Right System Size
How does this work in a real world example?
Suppose there are two neighboring homes.
In the first, the homeowner chooses a premium high-efficiency HVAC system that's too big because the contractor simply matched the previous unit. At the neighboring home, an HVAC professional installs a correctly sized, mid-efficiency system after completing a Manual J calculation.
While 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 properly matched to the home's needs.
Work With an HVAC Professional Who Designs Solutions Tailored to Your Home
Replacing your HVAC system should involve much more than selecting a model with the top efficiency rating. The right system is one that meets your home’s heating and cooling requirements.
At Brandywine Heating & Air, our experienced professionals 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 properly matched 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 tax rebates and provide information about HVAC financing options that make high-efficiency systems more accessible for all budgets.
Schedule an HVAC consultation online with Brandywine Heating & Air today. We'll gladly evaluate your home, answer your questions and help you choose the correctly sized efficient system that keeps your family comfortable for the long haul.