Common HVAC terminology every homeowner should know

Common HVAC terminology every homeowner should know

As a homeowner, it’s important to maintain your furnace and air conditioner by performing regular cleaning, changing your filters regularly, getting semi-annual tune-ups, and taking care of the little details that will keep your units running for years to come. If either your furnace or air conditioner isn’t working, it’s equally important to know some key terminology so that you can describe it to a qualified repair specialist.

These are the HVAC terms every homeowner should know.


An appliance fueled by gas, oil, electricity, or wood in which air or water is heated to be circulated throughout a home in a heating system.

This may seem like a no-brainer, but some homeowners confuse their furnace for their entire heating and cooling system or only certain components of the furnace itself.

Condensing unit

“Condensing unit” is the technical term for an outdoor air conditioner or a heat pump. It is called a “condensing” unit because it changes the refrigerant from its gaseous state to a liquid by cooling it. HVAC condensing units usually comprise the following components:

  • Compressor: Increases refrigerant pressure to keep the liquid refrigerant moving
  • Fan: Blows outside air through the heat exchanger to help cool the refrigerant
  • Condensing coil: Helps heat carried by the refrigerant to travel outside

Maintain your condensing unit (air conditioner) by keeping it free of leaves, excess grass, and yard debris so that it doesn’t overheat.

Cooling coil

Also known as an evaporator coil, a cooling coil is a coiled pipe usually made of copper, steel, or aluminum. It’s a channel meant to allow its contents to cool down, which in turn helps control the temperature of various other components of your unit, aiding in the heat exchange process.


A thermostat is a device that automatically regulates temperature and/or activates another device when the temperature goes above or below a specified threshold. Basically, your thermostat controls the temperature in your home by sensing the temperature and sending an electrical signal to your furnace or air conditioner to kick in.


A filter is any porous device that is used to remove impurities or solid particles from a liquid or gas. In the case of your HVAC system, a furnace filter is generally a simple cardboard and mesh construction that traps dust, pet hair, and other debris and prevents it all from entering your furnace.

Dirty, clogged filters can cause your furnace to work harder than it needs to, which can lead to motors burning out, so make sure you regularly replace your filter.

Condensate pump

A condensate pump takes in the water created in your HVAC system (usually in the form of water vapour in cooled or heated air) and pumps it out to a drain. A malfunctioning condensate pump can cause condensation to build up in your HVAC system, which can lead to mould, rust in your ducting, and other issues in the inner workings of your furnace.


In the context of HVAC, refrigerant is a gaseous or liquid substance used to cool various components of the system. The compressor in your A/C unit compresses the refrigerant, which makes it very hot. As it moves through the cooling coil, it cools down and becomes liquid. The liquid refrigerant then absorbs heat from the outside air and pushes the cold air out. Hot air in + cold air out = comfort.

If you find that your air conditioner is working but isn’t quite keeping up like it did the year before, it’s likely low on refrigerant.


A furnace humidifier helps to keep the humidity in your home at a moderate level so that the air isn’t incredibly dry all winter. Adding a humidifier to your heating system can help prevent those annoying static shocks, can keep your hardwood floors from separating, and can help with household allergens
like pet dander during the winter.

Knowing these key terms can help you hire the right person to fix your malfunctioning A/C or furnace, since you’ll be able to describe any issues you may be noticing. Knowing how these various components work will also help with your regular maintenance and cleaning.

If you suspect a faulty component, need a part replaced, or have any questions about your HVAC system, we would love to help. Call or text Pyramid any time at 204-694-5088 or send us an email. We perform all types of air conditioning, furnace, and HVAC repair in Winnipeg.