Despite being at our most advanced level of technology, humans are still unable to actually control the weather! We live and work best at a temperature of 71ºF, but it would be a challenge to find a location that can maintain this temperature at all times. Luckily, innovations such as HVAC systems allow us to control our immediate environments and keep them at a regular, comfortable temperature.

Modern HVAC systems regulate indoor temperatures as well as manage humidity, improve the quality of air in your home by filtration and purification, and replenish oxygen levels, all of which increase comfort and maintain a healthy environment. Like anything you use on a regular basis, it’s important to have some understanding of how they work.


What’s Behind the Acronym HVAC?

HVAC stands for heating, ventilation, and air conditioning, all three of which can be provided by an HVAC system in a single installation. Air is circulated by bringing in fresh temperature-adjusted air from the outside, and expelling stale air back out, with heating and cooling components to regulate temperatures.

Heating, ventilation, and cooling systems have become the most common upgrade in homes. An HVAC system is not as complicated as it may sound. Simply put, it is a combination of an air conditioner, a furnace, duct system, and a thermostat.


So How Does an HVAC Work Anyway?

Climate-control systems all have three main elements:

  1. Air conditioning unit and compressor installed outside of the house.A source of warm air, such as a furnace, and a source of cool air, such as an air conditioner.
  2. A means of air distribution, usually through ducts or pipes
  3. A control unit, AKA a thermostat, to regulate the system

In a centralized HVAC system, both warm and cool air can be routed through the same ducts and regulated by one thermostat. Heating and cooling act on the principle that heat transfers from a warmer object to a cooler one.

Contrary to its name, a heat pump is a climate control unit that both heats and cools the air. In cooler weather when you turn up the thermostat, the furnace consumes the oil, gas, or electricity that powers it and produces heat that is then distributed around your home through ducts or radiators, registers, or heating panels.

In the hotter months, a refrigerant gas inside a coil in your air conditioner is cooled to a liquid state when you turn on the AC. Warm air chills when it comes into contact with the cooling coil and is then sent through your home via ducts or directly from your AC unit.


How Does an HVAC Move Air Around Your Space?

There are three main distribution systems to move hot and cold air around your house. A Forced Air System moves temperature-controlled air through metal ducts via a blower. Gravity Systems are installed in basements and work on the principle that hot air rises and cold air sinks. As the air is heated, it rises and cool air sinks down, eventually reaching the unit and being reheated. Radiant Systems can be installed under floors but they usually heat implements like radiators, which then distribute the heat around the room.


The Elements of an HVAC System and What They Do

All HVAC systems have four main elements that work together. Different brands and models may have their own special features or be of better or worse quality, but the basic elements are similar:

  1. The furnace is fueled by natural gas or oil to heat air to the right temperature through a heat exchanger. Furnaces are usually found in basements, attics, or in some cases, specially built closets.
  2. The air conditioning unit uses electricity and has a refrigerant that cools the air. When hot air comes through the AC unit, it is sent outside while cool air is blown in. Unlike furnaces, AC units are usually installed on the outside of the home.
  3. HVAC stands for heating, ventilation, air conditioning. Your central heating and air conditioning system uses advanced technology nowadays to efficiently heat or cool your home or work place.The thermostat is the “brain” of the system and the element you will interact with most. It controls temperature and any other features that your system may have and turns different elements of the system on or off.
  4. Ductwork is the transport system for hot and cool air through the home. In modern homes, ductwork is factored in beforehand and usually installed above ceiling and behind walls.


HVAC Controls

Your HVAC is controlled by the thermostat. Thermostats are heat sensitive and control temperatures by detecting current air temperatures and reacting to bring the temperature back to the preferred temperature you have set, or the setpoint. If the temperature in the room is higher than the setpoint, the thermostat will automatically turn on the air conditioner and when it’s too cold, it will turn on the furnace.


Is it Time to Upgrade My HVAC System?

Technology in energy efficiency improves by about 7% a year, which means the latest HVAC systems can be up to 50% more efficient than systems installed 12 or more years ago. If your system or any of the elements we’ve looked above are more than a decade old, it may be time to consider an upgrade. You can usually start to see immediate, and sometimes very dramatic, decreases in power bills and you would save yourself hefty repair bills going forward by installing an up-to-date high-efficiency system.




Oval-shaped logo that says, “DM Select. Heating.Plumbing.Cooling.


A good HVAC system lasts an average of 10-15 years. If your current system is outdated or in constant need of repairs, it’s probably a good time to upgrade. DM Select Services offers affordable financing so you can get your dream system installed now. A modern HVAC system will efficiently heat and cool your home and keep the monthly power bills down too. Call us for more info on (703) 721-4844.