Choosing a new AC or furnace can be stressful. When you're looking to find the best HVAC system for your home, it's common to look for models with the highest efficiency ratings.
Surely the most efficient equipment should deliver the most comfort and lowest energy bills, right?
Actually, that’s not always the case.
High efficiency isn't the only thing that matters when it comes to new air conditioner installation or furnace replacement. Even though many focus only on efficiency ratings, proper HVAC system sizing is just as, if not more important for your home's comfort and your power bills.
Proper sizing has a major impact on humidity control and system longevity. The best HVAC system for your home balances energy efficiency and correct sizing.
In this article, 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.
High Seer Ratings: What Do They 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 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 is the current rating system for cooling equipment.
Fuel-burning heating system efficiency is evaluated by something called AFUE, which is short for Annual Fuel Utilization Efficiency. As with cooling efficiency ratings, 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.
However, high numbers don't by themselves guarantee lower utility bills. Actual heating and air conditioner efficiency depends on several key factors, including the quality of the installation, the state of your ductwork, how much insulation your home has, thermostat settings and, most importantly, system sizing. Even the most efficient system cannot operate at its best if it is bigger than necessary or smaller than needed for the home.
Why Proper HVAC Sizing Matters More Than You Think
Many assume a higher-capacity 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 sized based on your home's current heating and cooling needs—not just square footage or the size of the previous unit.
That's why reputable technicians complete an HVAC load calculation, also called a Manual J calculation, before suggesting replacement equipment. A Manual J calculation analyzes many details that affect your home's heating and cooling requirements, including:
- Home square footage
- Ceiling height
- Window size and placement
- Insulation
- Air leakage
- Regional climate
- Number of occupants
- Heat produced from appliances and lighting
- Ductwork condition
A properly sized air conditioner runs long enough to cool your home more uniformly while eliminating excess humidity. That means more consistent temperatures, better indoor comfort and improved moisture control. It also helps the equipment to perform more effciently, reducing unnecessary wear that can shorten its lifespan or lead to more repairs and higher repair costs.
When your heating or cooling system is correctly sized, you get better comfort and more reliable operation.
Problems with Oversized and Undersized Heating and Cooling Systems
You may be tempted to buy the most energy efficient, highest-capacity air conditioner or heating system on the market. The truth is, that often isn't a great idea.
heating and cooling systems that are bigger than your home needs or too small 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 works well.
- Short cycling: An oversized HVAC system starts and stops often, reducing efficiency and increasing wear.
- High indoor humidity: Oversized air conditioners finish cooling cycles too soon to remove indoor humidity from the air.
- Hot and cold spots: Some rooms get too cold while others aren’t ever cool enough.
- Additional equipment wear: Even though the system heats or cools your home fast, those repeated on-and-off cycles can cause avoidable breakdowns due to the strain.
Issues Created by 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 thermostat setting, which also causes extra strain.
- Trouble reaching the thermostat setting: Your home may never feel as cool as you want during hot weather or always feel chilly in the winter.
- Greater energy usage: Running almost constantly can increase utility bills.
- Added strain during extreme weather: HVAC systems that are too small can work harder in extreme temperatures, increasing component strain and the risk of breakdowns.
Why You Should Balance HVAC System Efficiency and Size
When weighing the pros and cons of a high SEER vs right-sized system, don't forget that you don't always need the top-efficiency model on the market.
Often, a correctly sized, mid-efficiency HVAC system will outperform an overly large 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 long-term needs.
As you consider how to choose a new air conditioner or furnace, consider:
- Energy savings: Higher-efficiency and right-sized systems can reduce electricity use.
- Upfront investment: High-efficiency AC and heating systems often have a higher purchase price than mid-range models but can reduce long-term energy costs.
- Energy prices: Areas with higher utility costs may see greater long-term savings from higher-efficiency units.
- Climate: It's crucial your heating or cooling system has enough capacity to handle areas with extremely cold winters or extremely hot summers.
- Time you plan to own the home: If you expect to live in your home for many years, the long-term energy savings of a higher-efficiency unit may offset the investment.
- Available rebates or tax incentives: Manufacturer promotions, {utility|equipment rebates and tax credits can offset the overall cost of higher-efficiency systems.
Real-World Situation: High Seer vs. Right System Size
How does this play out in a real world scenario?
Suppose there are two neighboring homes.
In the first, 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 correctly sized, mid-SEER or AFUE 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 have a longer lifespan because it's correctly matched to the home's needs.
Work With an HVAC Professional Who Designs the Right Solution
HVAC replacent or installation should involve much more than selecting a model with the highest efficiency rating. The right system is one that meets your home’s heating and cooling requirements.
At Home Comfort, our experienced professionals perform an HVAC load calculation. We'll evaluate your home's size and layout, your household's comfort goals and recommend equipment that's right for your home—not simply the highest-capacity, fanciest unit or the one with the highest AFUE or SEER2 rating.
Our team will let you know about 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 Home Comfort to get started. We'll gladly evaluate your home, answer any questions and help you choose the properly sized energy-efficient system that keeps your family comfortable for many years.