The Homeowner’s Guide to HVAC

For most of us, staying cool in the summer and warm in the winter has become a given expectation. Granted, this isn’t a new development—people have found ways to cool and heat themselves for millennia—but as the performance, efficiency and automation of home comfort increases, so does the difficulty to troubleshoot or find the best solution when something goes wrong.

Our progress is summarized today in four letters: HVAC. Standing for “Heating, Ventilation, and Air-Conditioning,” the HVAC acronym distills three complicated processes into one compact, modern term.

In this article, we will overview the different components contained in the term HVAC so you may feel more comfortable with your equipment.

Heating

Staying warm has always been a priority for humans, typically taking precedence over keeping cool. Our prehistoric ancestors huddled around fires. The Romans engineered underfloor furnaces, and coal-fired heating was used from the Tang Dynasty until the not-so-distant past.

Beginning as early as the eighteenth century and progressing through today, engineers developed more reliable, effective heating technologies. Two main types of home heating options emerged: hydronics and forced air.

Learn More: Heater Basics

Hydronic Heating

Hydronic heating refers to heating with water and works as follows:

1. A boiler heats incoming cold water
2. A pump moves the hot water through pipework
3. The pipes pass through radiators located in rooms around the house
4. As hot water passes through the radiators, heat is transferred to the surrounding space

Forced Air Heating

Forced air heating refers to heating air. A forced air heating system must contain the following:

1. A heat source, either a flame in a furnace or outdoor heat captured by a heat pump
2. A blower or fan to move heated air
3. Ductwork to transport the heated air to vents throughout the home

As will be explained more below, forced air heating and forced air cooling go hand in hand because they share the same blower and ductwork. While some homes have a “split” forced air system (where the heating and cooling components are separated), others have a packaged system, which combines all elements into one unit.

Northern climates will typically use a furnace/air conditioner combination because temperatures dip too low to capture outdoor heat during the winter effectively.

Southern climates will typically use a heat pump/air handler combination because temperatures stay warm enough to efficiently capture heat from outdoor air year-round via the heat pump.

Indoor Air Quality

The quality of your indoor air depends on ventilation and air purification.

Ventilation

When we “vent” to someone, we let problems out of our system by talking. Similarly, ventilation equipment sends pollutants out of the home.

These contaminants typically fall under one of three categories: moisture, germs, and particles, like dust and chemicals. Leaving these in the home would make it a dirty place while increasing the chance of getting sick.

Ultimately, the goal of an air ventilation system is to improve indoor air quality. To that end, there are two different ways of doing it:

1. Exhausting contaminants out of the home and bringing in fresh air
2. Eliminating contaminants while they are inside the home

You are probably familiar with some of the vents that exhaust air. Bathroom fans and range hoods above your stove remove smelly bathroom and kitchen odors, as well as potential carbon monoxide buildup in the kitchen. Attic, inline duct, and whole house fans, which remove air from multiple spaces at once, are other options.

Although these units remove the air, ensure you open a window to prevent negative pressure problems such as back drafting and mold. If you want one unit to both exhaust stale indoor air and bring in fresh outdoor air, install an air exchanger. Some can even transfer heat and moisture to preserve your indoor environment.

Learn More: Ventilation Basics

Other forms of ventilation freshen air flowing inside the home:

• Indoor air cleaners and purifiers can be as simple as your basic furnace air filter or as sophisticated as electronic and HEPA filters.
  
  The principle for all of them is the same. Air cleaners and purifiers connect to your forced air heating/cooling system and capture pollutants from the passing air. This not only protects your system from harmful debris but can improve air quality inside your home by removing smoke, pollen, dust, dander and potentially mold, bacteria, and viruses.
  
  
• Humidifiers, which add moisture to the air and dehumidifiers, which remove it, can help balance your home’s humidity levels. Overly-dry air can cause respiratory irritation, especially in those with asthma. Overly-wet air can cause mold growth.
  
  
• Ultraviolet (UV) lights are installed inside a central air system and destroy mold growth and other microorganisms, which both improves the system’s efficiency and provides for cleaner air passing through the unit.

Air Conditioning 

A/C, the last part of the HVAC acronym, is barely a century old when it comes to residential use. Throughout most of history, people were limited to using handheld fans and other primitive devices to stay cool. Then, in the early twentieth century, William Carrier invented the modern air conditioner and changed everything.

Central Air Conditioners

Contrary to popular belief, an A/C system doesn’t “cool” indoor air; it removes heat and makes use of the same components as your forced air heating system.

1. A blower, whether part of a furnace or air handler, moves air across an evaporator coil with super cool refrigerant flowing through it.
2. The evaporator coil removes heat and moisture, sending the now cold air through the home’s ductwork.
3. The heated refrigerant flows to an outdoor condenser unit, which dissipates the heat and sends the refrigerant back into the home system for another cycle.

Learn More: Air Conditioning Basics

Ductless Mini Splits

Mini splits are the next level in indoor heating and cooling systems. They consist of a single outdoor unit and up to eight indoor units. Each indoor unit blows room air over a cool evaporator coil and removes heat, like an air handler. The heat from each unit is then transferred to the outdoor unit, where it dissipates.

Mini splits offer the following benefits:

• Multiple units allow for zone control, meaning each room in your house can be the temperature you want.
• Mini splits can regulate their output to ensure a room always stays at the desired temperature, leading to improved comfort and efficiency.
• In addition to cooling, mini splits can also reverse the flow of refrigerant and provide heating during the colder months. So they can be considered heating and cooling units.

Learn More: Mini Split Basics

This library of HVAC system knowledge is designed to help you make the best indoor comfort choices for your home. If you need extra help, contact us at (866) 631-6389, and we’ll be glad to help.