HVAC Basics

HVAC Basics

HVAC systems are integrated solutions for heating, cooling, and purifying the air in a building. The acronym indicates their function: heating, ventilation and air conditioning. These systems can range from small installations suitable for single-family residential use all the way up to the huge rooftop installations seen on commercial properties.

How Does an HVAC System Work?

An HVAC system contains both a heating source (furnace) and cooling source (air conditioner) routed to the same ducts or pipes and controlled by a thermostat. When air temperature moves outside of the pre-set temperature range, the thermostat activates either heating or cooling (depending on settings and which is appropriate) to pipe in new, temperature-controlled air and pipe out old, stale air. 

Depending on the make of your HVAC system and the arrangement of your property, air may be filtered either at the furnace or at the air returns that sucks out the stale air. Typically, in buildings where the furnace is easy to reach, a central air filter is located at the furnace. If the furnace is not easily accessible, the air returns house filters so that the filters are easier to replace.

Most units use forced air with a blower, especially in newer buildings. Some older buildings may use gravity control. In these systems, a basement-installed furnace heats air, which rises through the ducts and displaces the cool air that sinks towards the furnace.

What are the Different Parts of the HVAC System? How Can I Tell the Different Air Registers Apart?

A complete HVAC is composed of the furnace, the air conditioner, the ducts, the thermostat and two types of fittings that may look similar to the casual observer: air supply vents and air returns. Supply vents pump air into the rooms in the house and air returns pull the old air out. In systems with decentralized filtration, the air returns contain the filters. Air returns are generally larger and fewer than supply vents, which may be smaller but present in most or all of the rooms. Otherwise, they may look similar. If you’re unsure which is which, turn on the air conditioning or heat and see which way the air is flowing – into the ducts (return) or out (supply vent).

What Else Should I Know?

Proper maintenance is important. Be sure to change your filters at least twice a year. Dirty filters will no longer do their jobs effectively and can block airflow, making the system work harder than it should.

If you’re choosing an HVAC system to install in your property, know that forced air styles are faster acting but typically require more maintenance than gravity systems which have fewer moving parts. It is also usually more difficult to filter air effectively in gravity systems, so if air quality is a prime concern, opt for forced air.

What is Envisivent? What Role Does it Play in My HVAC?

Envisivent is a Mud-in Flush Mounted Air Return Vent that blends seamlessly into walls and ceilings for a contemporary aesthetic. 

Designed to be installed during the drywall stage in a few easy steps – mud, tape, sand, & paint.  

The air return covers now become part of your wall.  A sleek alternative to bulky metal grilles that protrude. They work like a traditional air register return vent but its balance of form and function elevates a traditionally utilitarian HVAC component into a design choice that adds design value to the property.

You have options…the vents come in two styles: a permanent vent cover (not removable after installation); and, a removeable vent cover,  which uses magnets to allow the cover to be removed if desired. 

Envisivent is designed and manufactured in Canada, where we control every step of the production process to ensure consistent quality. 

Looking to purchase?

Envisivent products are available through select drywall supply retailers and also available online at

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