HVAC systems keep homes and businesses comfortable in the warmer months by circulating air through ventilation, cooling and filtering. They also heat spaces, control humidity levels and eliminate harmful gases.
The V in HVAC stands for ventilation, which involves an HVAC system’s air handler, ductwork and return vents providing mechanical ventilation that reduces humidity, normalizes temperatures and exhausts carbon dioxide and other pollutants. Contact Ausco Air Heating & Air Conditioning for professional help.
When you think of heating and cooling systems, you probably envision ductwork delivering conditioned air throughout the home. However, there are other options for delivering heated and cooled air, including vents that can be used individually or in groups, as well as whole-home ventilation systems.
HVAC systems can be powered by gas, electricity or other energy sources. In general, the higher the efficiency rating of an HVAC system, the lower its operating costs will be. This is especially true for systems that are ENERGY STAR® certified, which have been independently verified to meet stringent energy efficiency standards.
Furnaces and boilers generate heat, which is distributed via ductwork in homes during colder weather. They are often rated by their Annual Fuel Utilization Efficiency (AFUE) or Heating Seasonal Performance Factor (HSPF). A furnace that is rated 80% AFUE or higher will use less fuel to produce the same amount of heat.
Other components of a HVAC system include ductwork, vents, registers and thermostats. Ductwork is typically divided into supply and return ducts to control the flow of conditioned air. In addition, the supply ducts can be connected to individual rooms through vents or registers, which can be controlled by dampers. Vents can also be equipped with filters to remove dust, pollen, odors and other allergens from the air.
Air cleaners, humidifiers and dehumidifiers can be added to HVAC systems for improved indoor air quality. They can reduce odors, mold and mildew growth, as well as improve asthma and other respiratory conditions by removing harmful substances from the air. These can be circulated by the system’s air handling unit or by a separate vent.
Cooling
The cooling systems in hvac use the same principles as heating systems to cool indoor air. They pull in air from the outside, heat it with electricity or a fuel (gasoline or natural gas), and distribute it throughout the property through ductwork. The ductwork includes vents and registers that allow conditioned air to enter rooms and return the cooled air to the system.
The evaporator coil in the air handling unit absorbs heat from the incoming air, and the blower fan pushes the air through the ductwork to the rooms. The air filters remove dust, pollen, and other contaminants from the conditioned air. The refrigerant gas then travels to the compressor, where it’s pressurized and turns into a liquid. The liquid then travels to the condenser, where it releases the heat into the outdoor air.
Some systems include an economizer mode that uses fresh outside air to cool the building. When this feature is active, the control system will open the outdoor air damper and close the return air damper. It will then compare the temperature of the outdoor air to the demand for cooling. If the temperature of the outdoor air is lower than the demand, it will shut off the air conditioner and use the outdoor air to cool the building.
All HVAC equipment must be properly sized and matched to its intended application in order to achieve optimal efficiency and comfort. The equipment must also be maintained by qualified professionals to ensure the highest levels of performance. Newer HVAC equipment is generally more energy efficient than older models. However, even the most advanced equipment won’t perform as expected if your home or commercial facility isn’t well insulated and tightly sealed.
Ventilation
In the past, most homes had plenty of natural ventilation through gaps and cracks in walls and ceilings as well as opening and closing doors. But modern construction creates tightly sealed buildings that require a mechanical system for ventilation. The ventilation part of HVAC (the V in HVAC) takes many forms, but most systems consist of an air handling unit, ductwork, and air vents or registers.
The air handler contains the evaporator coil and blower fan that circulates conditioned air to rooms through a network of ducts. It may also contain filters that remove dust and pollutants from the air before it’s blown into living spaces. Some systems, such as heat-recovery ventilators or energy recovery ventilators, recycle sensible and latent heat from stale air by using thermal exchangers or enthalpy wheels.
Ventilation systems can also include gaseous filters that remove odors and volatile organic compounds from the air. They typically use permanganate oxidizers or activated charcoal and must be regularly maintained or replaced.
The ductwork is the main conduit for conditioned air in most ducted HVAC systems. It consists of supply ducts that distribute heated or cooled air and return ducts that bring the conditioned air back to the HVAC system. The air vents or registers are the openings in walls and ceilings where the conditioned air enters and exits the room. They may be equipped with dampers that regulate the flow of conditioned air into the room and can be adjusted to control temperatures.
Thermostat
The thermostat is the brain of your heating, ventilation and air conditioning system. It senses the temperature in a room and controls when your HVAC system turns on and off. It can have a significant impact on your home’s energy efficiency and comfort. Keeping your thermostat in good working condition is crucial to your HVAC system’s health. A broken thermostat can lead to inaccurate readings, which means your system may run more than it needs to or won’t turn off when the house reaches the desired temperature. Thermostat problems can also cause your utility bills to go up and lead to premature wear and tear on your equipment.
Thermostats come in a variety of styles, from simple mechanical models to programmable digital thermostats that can be controlled from a smartphone. Newer, smart thermostats can even learn your preferred temperatures and habits. However, you’ll need to make sure the model you choose is compatible with your HVAC system.
A thermostat’s sensor relies on thermal expansion to measure the air temperature. It consists of two metal strips bolted together, each made of different materials that expand or contract depending on how hot or cold they get. As the bimetallic strips bend, they create an electrical circuit that tells the furnace to produce heat or the AC to cool your space.
A thermostat needs a constant source of power to read the temperature accurately. Some use a wired connection that draws 24 volts from your home’s electrical system while others rely on backup batteries in case of an outage.
Filters
Keeping your HVAC system’s air filter clean can significantly reduce energy bills and extend the life of your equipment. Filters are essential for removing contaminants like dust, mold spores, pet dander, and mildew before they circulate in your home or business. A dirty filter restricts airflow, which can cause your system to work harder than necessary and increase your utility costs. Choosing the right type of filter for your needs is important, as well. Some filters are better for allergy sufferers, while others have higher MERV ratings that block smaller particles.
Fiberglass filters are the most common and cost-effective filters on the market. They are typically disposable and should be changed every 30 days. They are designed to trap larger contaminants, including lint, household dust, mold spores, pet hair, and bacteria.
MERV ratings range from 13 to 16. Filters with a higher MERV rating are available, but they can restrict airflow and can damage your HVAC equipment.
Electrostatic filters use electrostatically charged fibers to trap microscopic airborne particles, such as lint, dust, household allergens, mold spores, pollen, and pet dander. They are more expensive than fiberglass filters but may be an option for homeowners with respiratory problems.