How to Choose the Best HVAC System for the St. Louis Climate

Your home’s heating and cooling system doesn’t just keep you comfortable year-round—it also helps regulate indoor humidity to prevent mildew, mold, and dry skin. When you’re trying to find the best HVAC for St. Louis, it’s important to consider both the city’s hot, humid summers and its chilly, often unpredictable winters. Choosing the right system means balancing efficiency, comfort, and durability in a climate that demands year-round performance.

Not sure which system is right for your home? Start by exploring how different HVAC options handle St. Louis’s unique climate—or let our team help you choose the perfect fit for year-round peace of mind.

 

Understanding St. Louis’s Unique Climate and Your HVAC System

Temperature history in 2024 in St. Louis by Weather Spark

 

While your St. Louis home may not experience the most extreme weather in the country, you’ll still face plenty of challenges that interfere with your goal of staying comfortable year-round. Summer heat waves can occasionally push temperatures past 100°F, and even the more typical highs of 80 to 89°F can strain undersized cooling systems.

Choosing the right HVAC equipment—including professional AC installation—is key to ensuring your system can keep up with the demands of the season.

Dealing with Humidity and Cold Weather in St. Louis

High humidity also plays a big factor in the climate of Saint Louis, MO. About 18% of the days are muggy or worse, from May to September. That means your cooling needs must include adequate dehumidification, or the cool air won’t provide the expected comfort level.

When winter rolls around, and it’s time for warmth instead, you’ll definitely want a reliable heating system to keep your home warm. The St. Louis climate brings winter lows of 25 degrees F or below from November through February.

Storms can drop temperatures below 0 degrees F, while daytime highs tend to top out around 41 degrees F until spring comes. Investing in quality heating equipment like a gas furnace or properly sized heat pump will keep you warm no matter how cold the temperatures drop outside.

7 Top Factors That Influence Your HVAC System Needs

Aside from the harsh climate that we experience here in the St. Louis metro, there are other factors that weight in when considering the best type of HVAC system.

• Air Tightness: This is how well a building prevents the uncontrolled flow of air in and out through gaps, cracks, and penetrations in the structure (walls, ceilings, floors, windows, doors, etc.).
• Home/Business Size: The square footage of your home or business directly affects how much heating and cooling capacity is required.
• Home/Business Layout: While the size of your home or business is largely used to size heating and cooling equipment based on square footage, the layout and airflow between rooms also affect the final decision.
• Insulation level: Poor insulation means more heat loss in winter and heat gain in summer, resulting in greater HVAC needs (or improved insulation).
• Ductwork Condition & Design: Poorly designed ductwork can reduce HVAC system efficiency by up to 40%.
• Number of Occupants & Lifestyle: More people = more body heat + humidity = different load on the system. Suppose your home is occupied 24/7 vs. just evenings or weekends; that also affects programming needs and equipment selection.
• Other Factors: There are other factors that ultimately play into the type and model of HVAC system that’s best for you situation.

As you can see, it’s a complex calculation that is best left to HVAC professionals.

Types of HVAC Systems That Perform Best in St. Louis

As experts in HVAC, these are some of the best options for a residential HVAC system.

A. Central Air Conditioners

For newer homes with existing ductwork, a central air conditioner is the best option to stay cool.

The AC unit is usually placed on the ground outside of the home, requiring no special support on the roof or space in the attic.

We install Carrier’s residential models, such as the Infinity 19VS, which provides unparalleled comfort and energy efficiency of up to 19 SEER2. SEER2, or Seasonal Energy Efficiency Ratio, ratings run from around 8 to 21+, with higher ratings offering greater savings in the long run.

If maximum efficiency is your goal in a new air conditioner, only the Carrier Infinity 26 Central Air Conditioner with GreenSpeed Intelligence will do.

It offers an unparalleled SEER2 rating of up to 26 and the lowest level of noise possible.

No matter the model you choose, our air conditioning installation services will ensure the system is up and running as soon as possible.

B. Heat Pumps

Heat pumps are modern devices that can provide both forms of temperature control in one convenient package.

These pumps rely on technology similar to what’s found in your refrigerator to move heat in or out of your home’s air, depending on the season. It can move heat out of your home in the summer and then bring it in during the winter despite cold outdoor temperatures.

You can also connect a central heat pump to your existing ductwork and enjoy the same service you would receive from a separate AC unit and furnace.

These systems tend to offer good to great energy efficiency as well, with the Carrier Infinity 24 heat pump with Greenspeed Intelligence rated at up to 24 SEER2.

These energy-efficient systems are ideal for dealing with fickle spring and fall weather, where you might need both heating and cooling on the same day.

The EPA estimates that switching to a heat pump could save you up to 75% of the energy used for electric resistance heating in particular, like traditional furnaces.

C. Ductless HVAC Systems (Mini-Split Systems)

Older homes in St. Louis that lack existing ductwork—or have outdated, inefficient ducts—are ideal candidates for ductless HVAC systems, also known as mini-split systems.

These systems provide zoned comfort, meaning you can control temperatures room by room and reduce energy use by only heating or cooling occupied spaces.

Mini-splits are especially effective in homes where traditional HVAC installation isn’t practical. They don’t require ductwork and offer high efficiency with advanced technology.

Many units also operate quietly and offer excellent humidity control—perfect for dealing with the muggy summer months in Missouri.

One standout option is the Carrier Single Zone Infinity 37MPRAQ0 Ductless Unit. This model delivers both precision comfort and energy savings, making it a great choice for targeted heating and cooling.

Carrier also offers multi-zone models like the Performance Series, which delivers SEER ratings up to 23.8, and indoor wall units that operate as quietly as 27 decibels—about as soft as rustling leaves.

D. Gas Furnaces & Fan Coils

Winters in this part of Missouri can leave you shivering, but reliable gas furnaces and fan coils will keep your home warm throughout the season. Traditional furnaces often play a part in the best HVAC systems for St. Louis homes.

Even if you want to use a heat pump to save energy on those chilly fall evenings, you may still need a natural gas furnace from Carrier to deal with the depths of December and January’s low temperatures.

Carrier’s new furnace options include the Infinity 96 High Efficiency Gas Furnace. It provides whisper-quiet performance and up to 96.7% Annual Fuel Utilization Efficiency. Our furnace installation process is quick and easy, getting you back to enjoying a warm home despite the chill. Of course, you’ll still need to choose the right cooling system after settling on a furnace for heating.

We also provide fan coils, a residential HVAC option you might not have heard of before. They provide a duct-free cooling or heating option you can install anywhere that’s needed.

An internal coil provides the heating or cooling effects while connecting to a central system, giving you far better efficiency than you could achieve with space heaters or portable air conditioners.

If you just need a boost in cooling or heating in a particular part of the home, a fan coil is likely the best addition to your existing system.

Which HVAC System Do You Need in St. Louis?

If you’re still not sure which type of unit you need, let us help you understand at a high level which unit would probably serve you best. If you have existing ductwork and need to cool your home, a new central AC unit is what you likely need.

If you have milder cooling and heating needs, a heat pump would probably best serve you. If you do not have existing ductwork, a mini-split ductless HVAC system is the way to go.

For serious heating needs (typical in our climate), go with a gas furnace. And finally, to boost the performance and for zoned heating and cooling, a fan coil will be the best.

While this table may help, don’t hesitate to request a free estimate so we can help you determine the best unit for your specific needs.

Commercial HVAC Systems

Commercial HVAC services give business owners the peace of mind to know their facilities will stay comfortable and safe to use, no matter the conditions. Carrier can provide equipment that lives up to the challenges of manufacturing facilities and warehouses, so your commercial HVAC system will last for years with minimum maintenance as well.

Choose a heating and cooling company that has the expertise to handle both types of installations.

Key Features to Consider When Choosing a System

Choosing the right HVAC system isn’t just about heating and cooling—it’s about long-term performance, energy savings, and peace of mind. Whether you’re replacing an aging unit or installing a system in a newly built home, there are several key features to evaluate before making your decision. From efficiency ratings to smart technology integration and warranty protection, each component plays a vital role in how your system will perform in the St. Louis climate.

SEER Ratings

The Seasonal Energy Efficiency Ratio (SEER) system allows you to compare the energy efficiency ratings of HVAC equipment like air conditioners and heat pumps. The numbers range from around 8 to above 21. For energy-efficient heating systems like furnaces that run on fuel such as gas or oil, you’ll want to compare the Annual Fuel Utilization Efficiency (AFUE) rating instead.

Smart Thermostats and Automation

Modern HVAC systems aren’t just about temperature—they’re about intelligent comfort management. All of Carrier’s latest equipment is fully compatible with today’s smart thermostats, allowing homeowners to take full control of their indoor climate while maximizing energy efficiency.

These devices offer powerful features like remote access, customizable schedules, and real-time energy monitoring that help reduce waste and lower monthly utility bills.

One standout option is the Carrier digital smart thermostat, which integrates effortlessly with Infinity® system components. This advanced thermostat offers intuitive touchscreen controls, wireless connectivity, and personalized settings that adapt to your daily routines.

Whether you’re adjusting the temperature from your phone while away or setting automatic temperature changes for day and night, the system ensures consistent comfort and better control over energy usage.

By upgrading to a smart thermostat, you gain more than convenience—you invest in long-term efficiency, comfort, and peace of mind.

Warranty and Ongoing Product Support

Manufacturer warranties, such as a 10-year warranty on furnace parts from Carrier, protect all of the HVAC units we install. If you need help with anything we install, we can dispatch service technicians to make repairs within hours.

HVAC Maintenance & Ongoing Support

Speaking of support, you can turn to us at Crystal Heating and Cooling whenever you need regular HVAC maintenance. An annual visit for furnace maintenance can save you thousands of dollars in the long run by helping you put off costly repairs and replacements for years to come. Call us for HVAC issues like a lack of comfort, rising energy bills, or equipment malfunctioning.

Our emergency repair service will prevent winter storms or heat waves from interrupting your usual routine. Don’t forget about occasional air duct cleaning as well to keep dust and mold out of your home’s air. Give us a chance to provide you with HVAC maintenance twice a year, during the spring and fall, for a system that won’t give up when you need it the most.

Why Carrier Products Are the Smart Choice

We highly recommend the exclusive use of Carrier equipment in your home because it provides the highest level of durability, the best integration with cutting-edge tech, and a great price. Not only can you take advantage of new installation advantages, but you’ll also get great service and support from us through the lifespan of the equipment. We specialize in customer satisfaction, and so does Carrier.

Choosing Crystal as Your HVAC Partner in St. Louis

It’s essential to choose air conditioning companies that provide only certified technicians. Here at Crystal Heating and Cooling, each service provider we send out is fully North American Technician Excellence (NATE) certified. We offer Carrier-backed installation services, furnace repair, heat pump repair, air conditioner repair, and more.

We’ve been serving the go-to Heating and Cooling company in the St. Louis area since the 1960s, and our years of experience in the area allow us to make personalized recommendations for every home.

Our customers consistently rank us among the best HVAC companies in the area. Many customers even thank their favorite HVAC technician by name in our reviews. Stick with the HVAC experts in St. Louis and request a free estimate.