Understanding Your HVAC System: Heating, Air Conditioning & Ventilation

Whether keeping your home cozy in the winter or cooling your office in the summer, HVAC systems are a part of everyday life.

Your HVAC (heating, ventilation, and air conditioning) system is the system or combination of system used to provide a comfortable temperature in your home and maintain high levels of air quality. As a homeowner, it is important to understand the key roles your HVAC system plays and how they operate in order to get the most out of your system.


The heating component of your HVAC system provides a warm climate for your home in the cooler months of the year. Today, the most popular type of heating system is the forced air system, but many homes also use radiant heat systems and geothermal heating systems, among others. In all of the systems, heat is created at a central source and distributed through the home via different means.

Forced air

These systems use a furnace to heat the air and then disperse it through the house via ductwork and in-room vents.

Radiant heating systems

These use heating stoves or a boiler to disperse heat through the house via a network of electric heating coils or hot water tubing installed in the floor or ceiling.

Geothermal heating

These use the constant temperature of the ground created by absorption of the suns rays to generate heat for your home via a heat exchanger.

No matter which type of system you have, your HVAC system makes your home warm and enjoyable for you and your family during the winter months.


Your HVAC system plays an important role in maintaining the your home’s indoor air quality. Ventilation helps circulate and purify air, control moisture levels, remove unwanted smells, and prevent air stagnation.

Depending on the age of your home and the HVAC system you have, this may be done either mechanically, naturally (via fans and windows), or through a combination of the two.

Forced air systems, discussed above, pass the air in your home through an air filter to keep airborne particulates, volatile organic compounds (VOCs), and allergens out of your home. If you do not have a fixed air system, this can also be done using tools like air cleaners, air purifiers, humidifiers, and dehumidifiers.

Understanding how your system keeps your home ventilated is the first step to addressing any breathing or allergy issues you and your family may be encountering throughout the year.

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Air Conditioning

Your HVAC system is also in charge of keeping you cool during the warmer months. There are several different types of AC units, each with their own pros and cons. Whether you have central air (used in conjunction with forced air systems), split or ductless AC units, window AC units, or portable AC units, the process that each system uses to cool your home is similar.

Your AC system circulates refrigerant that changes from gas to liquid as it collects and expels heat from your home. It passes warm vapor refrigerant through the compressor where it becomes hot refrigerant vapor and moves to the condenser. Here, the hot vapor is cooled as air from the condenser fan passes over finned coils and turns into hot liquid. The hot liquid passes through the expansion valve that creates a low pressure, cool liquid mist that runs through the evaporator coil.

As the cooler liquid mist evaporates, it absorbs heat from your house’s inside air and returns it to the compressor (restarting the process). This absorbed heat is pushed outside by the system, resulting in a cooler home.

Now that you understand the roles your HVAC system plays in your life, you will be better prepared to maintain your system, learn more about your system, determine what your system is missing, and purchase a new system if the time comes.

Need help with your system? Hire an HVAC Contractor

Since an HVAC contractor spends hours in your home working on the systems that will keep your family comfortable, it’s important to ask the right questions and know what to look for in an HVAC contractor. Here are a few tips for hiring the right HVAC contractor for your needs:

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The most important tip I can give you is to only hire a qualified HVAC contractor. How do you know if a contractor is qualified? Ask!

Before you even begin talking about the problems you’re having with your system, ask your contractor about licensing and insurance. Are they licensed by the state? Do they carry insurance? Each state has different requirements for obtaining a license to repair/replace HVAC equipment, and it’s important that any contractor you consider meets these qualifications. Ensure you understand the licensing requirements in your state, city, and/or county, and request copies of a contractor’s licenses to know you’re working with qualified people.

The next most important thing to ask is whether or not the contractor’s technicians are NATE certified. The North American Technician Excellence (NATE) only certifies technicians who have undergone rigorous testing and proven themselves to be the top in the industry. While many technicians service units without the industry’s gold standard certification for excellence, don’t settle for anything other than the best when it comes to your family’s health and comfort.

Price is important, but only if it’s guaranteed

Pricing is always an important part of the decision to hire any contractor. When it comes to choosing your contractor, look for one who will guarantee the project pricing upfront. Now, there will be issues that no contractor will be able to find until they get in there and start servicing the unit, but good contractors will do their best to minimize those costs.

A quality contractor will not try to provide an estimate over the phone. They will ask questions about the issues you are having and then suggest scheduling an in-home evaluation to determine the problems and the costs associated with the work. While assessing your project, they will build a contingency into the estimate to account for potential issues that may occur once the project is started and those unforeseen issues that push homeowners outside of their budgets.

Low-price initial estimates can be enticing, but they often do not account for the kind of issues that can surprise homeowners. In order to avoid unforeseen issue sticker shock, only work with contractors who will guarantee the project price before starting the job.

Place a high importance on sizing

When you talk to contractors about replacing your unit, make sure they include a size assessment for your home. In addition to the other questions you’re asking, ask about the tools the contractor will use to identify the right-sized unit for your home. If they talk about using tools like a blower door test, air flow capture hoods, hygrometers, refrigerant charging scales, and computerized HVAC load calculations, then they are using the most advanced technology to ensure the right-sized unit makes its way into your home.

When it comes to your HVAC system, size matters. A system that is too large or too small will undoubtedly increase your utility bills. HVAC system size has only recently — in the last decade or so — been found to play an important, and expensive, role in your home’s energy efficiency.

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