How Does My HVAC System Work?

Ever wonder how your home is able to stay cozily warm on cold winter nights, and invitingly cool on a hot summer’s day? There’s no secret about it: it’s your HVAC system that keeps air flowing throughout your home and maintains a pleasant temperature inside.

But how exactly does it all work? It’s not magic: it’s science and engineering.

How Most Residential HVAC Systems Work

Most residential HVAC systems use a split system, also called central heating/AC or central HVAC, which has a furnace for heating air and an air conditioner for cooling it.

The furnace heats air inside a super hot environment that is sent through the home by means of the blower. Furnaces are powered by a variety of energy sources, including gas, electricity, and oil. Gas furnaces are the most common, as they tend to be the cheapest to operate.

The blower then takes the air and blows it throughout the house through ductwork installed in the home. Not all homes have ductwork, but most homes with split systems need it to push the air through.

That describes heating, but what about cooling?
Air is brought into an outdoor air conditioner unit, which is then cooled with refrigerant and blown through the home. Refrigerant flows through the air conditioner unit and is changed from liquid to gas depending on where it’s flowing through. The air conditioner unit has a condensing unit, which refrigerant flows through and is condensed from its gas form into liquid. Then this liquid flows through to the evaporator unit and is evaporated back into a gas. This evaporation cools the air, and this process of going from liquid to gas keeps the refrigerant able to cool the air.

What Are The Kinds of HVAC Systems?

There are many kinds of HVAC systems, however we’re only going to discuss the most common systems in modern detached homes.

Heating-Air Conditioning Split System

This is the system described above. It’s the most common type of HVAC system in American homes today, due to the fact that it can work in nearly any climate zone while also being able to heat and cool down homes of nearly any size.

Most split systems require ductwork installed in homes. However, there do exist mini split systems that blow air throughout the rooms without ductwork. These systems are generally for smaller units and older homes that do not have ductwork installed already.

Heat Pumps

Heat pumps are a type of heating and cooling unit that operates through extracting heat from the air, warming it, and blowing it through a room. It cools air in the opposite way, taking warmer air and cooling it down, effectively reversing the air flow.

There are other types of heat pumps called geothermal heat pumps that do not operate by taking heat from air. Instead, they take heat from a natural source like a body of water (water source heat pump) or the heat in the ground. Underground generally stays between 45 and 60 F, meaning there’s plenty of heat to extract for warming the air.

These systems are highly efficient, especially the geothermal types. They can cut energy usage costs by up to 70 percent.

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