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HVAC Basics: Understanding How Heating and Cooling Works

Apr 13, 2023


Your home’s HVAC system – heating, ventilation, and air conditioning – works hard all year to keep you and your family comfortable. In the winter, you crank up the heat to keep out the cold, and in the summer you blast the AC to cool off.


Because it’s run almost all year long, you want to make sure your HVAC system is in tip-top shape no matter what the season. It all starts with understanding HVAC systems. Once you understand the basics of HVAC, you’ll be able to maintain your system for better performance. A well-maintained system runs more efficiently, saving you money in the long run.

The HVAC Basics

For as long as humans have lived in homes, they’ve tried to keep out the heat of summer and the cold of winter. Nowadays, we have advanced technology that allows us to heat and cool our homes with the touch of a button or app.

For heating, HVAC systems rely on heat pumps, furnaces, or boilers, powered by electricity, to pull in air and warm it up before emitting it to the rest of the house via ducts and pipes. 

Air conditioning works by cooling air within the unit itself and then pumping it through ducts around the house.

Basic Principles of Heating

Air moves when it’s cooled or heated. Heat moves from warm objects to cooler ones to keep you toasty in the winter. This is called the heat exchanger.


The principle behind conduction is that heat travels through solid objects; think of touching the outside of a mug full of hot coffee. With your HVAC, heat is transferred from the source (see below), to the air inside the house through walls, floors, and ceilings.

Infrared Radiation

Heat travels in the form of visible and non-visible (infrared) light. In the case of HVAC systems, radiant heating panels emit (harmless and safe) infrared radiation, which heats up objects & surfaces in the room. 


Hot air naturally rises. Your HVAC system’s source (see below) will warm the air, which is then circulated through ductwork and replaces the cooler air in your home.

Types of Heating and Cooling Systems

The type of heating and cooling system you use will depend on several factors, including where you live, what type of residence you have, and your budget.

Heat and Cooling Sources

No matter what type of HVAC system you have in your home, these components work together when the system is on. Knowing these will help you in understanding HVAC systems.


What gets the system started? How does the HVAC system make the air cooler or warmer?

Heat Pump

Heat pumps are electrically powered. They transfer heat from outside to inside or vice versa. For heating, they pull air from the outside and warm it up. The warm air is then circulated inside your home. For cooling, they extract hot air from inside to cool, releasing it outside to maintain a comfortable indoor temperature.


Furnaces burn fuel such as natural gas, propane, or oil to produce heat. This heat is then channeled through a heat exchanger (see above), which transfers the heat to the air. The warm air is distributed throughout the building via registers, radiators, or heating panels.


Boilers also work by using a fuel source, such as natural gas, propane, or oil, this time to heat water. The heated water is then stored in a tank or circulated through pipes throughout the building, providing comfortable heating.

Air Conditioning

Air conditioners circulate refrigerant gas through a system of coils that also absorb heat from the indoor air. The refrigerant then carries the heat to the outdoor unit, where it is released, and the cooled refrigerant returns to the indoor unit to repeat the cycle.


How does the warmed or cooled air make it through your house?

Forced Air

A blower or fan circulates heated or cooled air through ductwork and vents.


The heating source (usually a furnace) is installed in the basement. As it heats air, the hot air rises and is distributed throughout your home via a series of ducts without blowers or fans. This method cannot be used to cool a room or house.


The surfaces of a building – walls, ceilings, floors – are warmed up via hot water flowing through pipes. This method cannot be used to cool a room or house.

HVAC Troubleshooting

As much as we depend on our HVAC systems to keep us comfortable, sometimes they just don’t work as they should. 

Problem: The Unit Isn’t Cooling Properly

The AC in HVAC is meant to keep you and your family cool in those hot summer months. When it’s not working properly, everyone feels it. 

If your unit isn’t cooling your space properly, it might be due to low or leaking refrigerant, a worn out fan or compressor controls, or thermostat issues.

If it’s a problem with your refrigerant, call an HVAC professional since refrigerants can be dangerous if not handled properly. A professional will also be able to diagnose and repair any failure with the electronic controls, or a more serious issue with your thermostat.

Problem: The Unit Isn’t Turning On

You flip a switch, tap your app, or adjust the thermostat…and nothing happens. This could be due to a failure of the electrical components, or a failure of the thermostat. You might be able to fix this yourself by replacing a dead battery or flipping the switch on your circuit breaker, but if not, call in an HVAC professional.

Problem: There Isn’t Enough Airflow

Cold or warm air is coming, but weakly. This decrease in airflow could be caused by leaks or clogs in the ductwork or by dirty or clogged filters. In most cases, you can clean or replace your filters yourself, but when it comes to ductwork, it’s usually best to call in a pro to properly diagnose and fix the problem.

HVAC Maintenance

Providing your HVAC system with regular maintenance is simple. There’s not much you need to do very often; most DIY maintenance can be done just once a year.

For maintenance beyond typical care and cleaning, we recommend calling a pro. 

HVAC Maintenance You Can Do Yourself

Certain things you can do yourself to keep your home’s HVAC system in good working order.


Once a month:

  • Clean or replace reusable filters.

Once a year:

  • Clean dust and dirt off of the evaporator coil.
  • Clean the coil fins.
  • Remove dust, dirt, soot, and corrosion from the heat exchanger.
  • Check that air ducts and heating pipes are properly sealed.
  • Check window a/c units for proper window sealing.
  • Regularly clean your split system.


  • Clean your system’s drains by passing a stiff wire through the channels to prevent or remove clogs.

HVAC Maintenance That Requires a Pro 

Beyond basic maintenance, HVAC pros can perform more thorough checks to improve performance and discover problems before they start, as well as fix any issues that arise throughout the year.

Here are some of the professional-level preventive maintenance checks you can expect from CroppMetcalfe:


  • Condenser coil inspection
  • Motor lubrication
  • System safety
  • Compressor operation check
  • Electrical connection optimization and safety

Here are some of the problems with your heating and cooling system for which you might want to call in one of our 5-star pros:


  • Old or worn-out blowers in your a/c
  • A frozen evaporator coil in your a/c
  • Damages to inner parts
  • Leaky heating ducts
  • Broken thermostat
  • And more

Energy-Saving Tips

It’s easy to stay comfortable year-round and still cut down on your electric bill. Try these easy tips:


  • Set a programmable thermostat so you’re not heating or cooling an empty house
  • Hang blackout curtains to block direct sunlight in the summer
  • Install energy-efficient windows or apply window film
  • Upgrade and/or maintain your HVAC system
  • Use fans to circulate air

Call the Pros at CroppMetcalfe for All Your HVAC Needs

The best way to keep your HVAC system running smoothly all year long is with scheduled maintenance performed by the 5-Star technicians at CroppMetcalfe. We can increase the efficiency of your system to save you money on electric bills, spot small problems and fix them before they become major (and costly) issues, check the connections, ensure system safety, and more!

Call CroppMetcalfe today at 888-304-0678 or fill out our convenient online contact form to schedule your HVAC system maintenance check.


What Our Customers Say...

"I've been a CroppMetcalfe customer for 9 years and you have always provided outstanding service. I just had my semi-annual maintenance done, and I wanted to thank George for the truly outstanding service, professionalism, and excellent advice. He is definitely one of the best 5-Star Technicians I've had! Thank you CroppMetcalfe!"

Bill H