HVAC systems perform a variety of functions. These include heating (adding heat to raise or maintain temperature), cooling, humidifying and dehumidifying to regulate moisture content, ventilating to exchange indoor air with outdoor air, and filtering to remove biological contaminants like bacteria, viruses, and fungi.
Newer systems provide better comfort by regulating humidity and temperature, plus they have high energy-efficiency ratings. They can also save you money by lowering your utility bills.
The complex process of heating and cooling your home depends on a network of air ducts that distribute conditioned air throughout your living spaces. These ducts are made of a wide variety of materials, and they come in many shapes and sizes.
The insulated design of these ducts allows them to operate efficiently in both high and low temperatures. They’re also designed to resist corrosive fumes and chemicals. They’re an ideal option for industrial and commercial HVAC applications.
Supply ducts store cooled or heated air until it’s delivered to rooms in your home through vents or registers. Depending on your needs, you may prefer aluminum flex ducts or vinyl-insulated fiberglass (VIG) ducts. Both offer exceptional durability and are cost-effective. However, fiberglass can irritate your skin and nasal passages.
Unpleasant odors, mold growth around vent covers and other signs of a ductwork infestation are indicators that it’s time for an inspection and cleaning. Unexplained allergies or respiratory symptoms can also signal contaminated indoor air. Pet dander and hair are especially common allergens found in ductwork, but cleaning can help reduce them.
Duct Transitions
Duct Transitions, also known as duct connectors, help air flow from different sizes of ductwork. They are critical for a successful ventilation system, such as in getting fresh air to the air diffusers and exhaust air to the extractor ducts. Duct transitions include a wide range of shapes and sizes to fit the needs of your ventilation system. Examples include T Duct Transition, Y Duct Transition, and Reducer Duct Transition.
A duct transition is needed whenever a duct run changes in size or shape, such as when moving from rectangular to round ductwork. These ductwork fittings can be purchased pre-made or you can build them yourself. If building your own sheet metal transition, make sure to follow the safety tips and steps to fabricating a safe, durable and high-quality product.
In a multi-level residence, a duct system typically includes a vertical ell that joins the main trunk line with a chase going up to the next level. Having too many vertical ells in the duct system can cause excessive restriction and add to TEL (total equivalent duct length). To prevent this, install a ductwork fitting called a vertical duct tee, or reducer, at the top of the chase. This will allow the trunk to continue up the chase, while allowing any supply runs tied into the side branch to receive more cfm.
Plenums
Plenums play a key role in heating, cooling, and distributing air. They are used to improve airflow, boost efficiency, and increase comfort. They can also help regulate temperature and humidity consistently.
The supply plenum box connects to the ducts that distribute the heated or cooled air throughout your home. The plenum box receives the air from your furnace or air handler unit and then distributes it to smaller ducts, which in turn deliver the conditioned air to various rooms.
A return plenum works much the same way as a supply plenum, but it collects the used conditioned air that flows through your system’s return vents and redistributes it back to your furnace or air handler unit for conditioning again. Typically, a return plenum is fitted with an air filter to ensure that the conditioned air is clean when it returns to your system.
The plenum is also responsible for routing electrical, network, and communication cables within your home. These cables must be rated as plenum-rated in order to be routed through the air circulation space. This means they are made of fire-resistant materials such as PVC, fluorinated ethylene polymer (FEP), or polyolefin that don’t produce large quantities of smoke in the event of an emergency.
Supply Registers
A supply register, also called a vent, allows the heated or cooled air your HVAC system produces to exit its air ducts and enter a room. These slatted openings on the ceiling, wall and floor have adjustable dampers for controlling air flow direction and intensity.
Most homeowners don’t interact much with their AC unit beyond changing the thermostat settings. But your home’s HVAC system actually does a lot of behind-the-scenes work to maintain air pressure, quality and circulation. It depends on proper ductwork and air return and supply vents to do so.
Vents have both a functional and decorative role in the home. With a variety of designs and finishes, they add a touch of style while serving their purpose. Choose a vent that becomes a room focal point, or one that blends seamlessly with the overall aesthetic.
A register or diffuser is a type of vent that has an adjustable damper and external louvers. They can be used as supply vents or returns and are available in a wide range of sizes and styles. They’re usually sized with the long dimension first, like 10×6 or 12×8, for ceiling and sidewall registers. For floor and floor vents, they’re typically described with the short dimension first, such as 4×10 or 4×12. Grilles, on the other hand, have no damper or adjustable louvers. They’re best suited for return applications.
Return Grilles
Return grilles are a must for any HVAC system. They suck air back into the duct system to be heated or cooled again before it gets pumped back out to your rooms. They can be purely functional or decorative and are located in the ceiling, near the floor, or on a wall. If you’re not sure whether a vent is a supply or return vent, there is a simple test to do. Hold a piece of paper up to the entrance of the vent when the system is running and see which way it is pulled. If it is pulled away from the vent, it’s a return vent; if it’s pushed in towards the vent, it’s a supply vent.
It’s important that your return vents not be blocked as this can decrease the efficiency of the system and can cause it to wear out earlier than it should. This is especially true if the return ducts are undersized.
A return vent that’s not properly sized can be noisy as it tries to pull in air at too high a velocity. The ideal speed for a return vent should be in the 300 FPM to 500 FPM range.
Dampers
Dampers are rectangular or round devices that fit inside your ducts with a door that opens and closes to regulate airflow to specific zones. These help control how much hot or cold air enters a room, so the HVAC vents can be closed to reduce conditioned air delivery to rooms that aren’t in use. This allows a home to save energy by taking rooms off the air supply, preventing unnecessarily cooled or heated areas in an otherwise efficient system.
They’re adjustable with a handle and come in two varieties: parallel blade dampers and opposed blade dampers. Parallel blade dampers are better for maintaining airflow while opposed dampers win the gold medal when it comes to directing airflow. Both have the option of being manually or electronically controlled.
Louver dampers offer high-quality functionality, compatibility with various duct sizes, and easy operation with just a twist of the hand. They’re also one of the best options for cold climates, but they may not be as effective in warmer regions. For automatic control, look for actuators with a spiral spring in the center of the damper that can return the sheet metal dampers to their desired default power-fail position in the event of a power outage.
Insulation
Insulation provides protection, cost effectiveness and sustainability to HVAC ducts, vents and piping. It ensures a regulated air temperature is maintained as it travels through the duct system, and helps prevent energy waste by reducing the need for the system to overwork.
It also contributes to a healthier indoor environment by preventing the release of harmful airborne fiberglass particles into the atmosphere, which can cause irritation to the skin, eyes and respiratory system. These particles are particularly dangerous to vulnerable individuals, such as children and those with pre-existing respiratory conditions.
Whether installed on hot or cold ductwork, proper installation and maintenance of insulation is vital to its longevity. This includes a clean surface and the use of high-quality HVAC foil tape to secure and create an airtight seal, ensuring optimum performance. The type of facing or barrier used is also important, with common options including kraft paper, white vinyl sheeting and aluminum foil. Each of these materials can act as an air and vapor barrier if properly installed, and the right choice will depend on climate, construction type and other factors.