Air Conditioning Ductwork

Published Categorized as Air Cooling
Air Conditioning Ductwork

Air Conditioning Ductwork: The Definitive Guide

While most people enjoy the benefits their air conditioner in their home provides them, not may people realize just how extensive the overall system connected the the air conditioner actually is.

Aside from the external air conditioning unit and the internal air handler, there are also intricate ductwork designs that have been engineered and carefully laid out in order to achieve the maximum cooling and heating efficiency possible.

What Is Ductwork?

Ductwork is simply the series of tubes and passageways that connect the main air conditioner to each individual room in the house.

Traditional ducts can be rectangular, square, round, or oval in shape, however, fabric ducts are more free-form and have no defined shape to speak of.

Ducts can be rigid or flexible, depending on the location they are being used in and the ease of access to their destination point.

A standard ductwork design layout consists of one main duct extending from the main air conditioning unit. Several branches, or take-offs, extend from the main duct and connect to specific rooms at either a ceiling, floor, or wall vent.

Larger rooms may have several vents, while smaller rooms tend to only have one vent. The size of the duct leading to each vent is determined by the volume of air needed for that room as well as the number of ducts that will be providing air flow to the same area.

A properly designed ductwork system can take full advantage of the maximum effectiveness and efficiency of your air conditioning unit.

What Is Ductwork Made From?

Air conditioning ductwork can be made of various materials including aluminum, plastic, and fabric. Ducts are often insulated with a form of fiberglass material called glass wool, which is occasionally bended with polyester fiber.

Rigid Ducts

Traditional rigid ducts are made with thin aluminum sheet metal rolled into tubes or formed into squares or rectangles. The metal is then covered in a layer of insulation material before being installed.

Of all the traditional varieties of ductwork, aluminum ducts are the lightest and easiest to install.

The second type of rigid ductwork is made from insulated panels created with polyurethane foam coated with a think layer of aluminum. The main benefit of these panels is that they incorporate the support system and the insulation into one piece.

Rigid ducts are extremely energy efficient, which means they are able to maintain the temperature of the air that is being passed though them at fairly consistent levels.

However, because of their solid design, they are usually reserved for fabricating the main duct line in the overall ductwork system and not the smaller branches that run to specific areas of the house.

Flexible Ducts

Flexible ductwork is created by taking a semi-rigid coiled wire and coating it in plastic sheeting. This flexible tube is then wrapped in glass wool insulation and then coated again in a plastic material. The result is a variety of duct that can be run around various corners and most angles with ease.

The downside of flexible ducts is that they are not as energy efficient as the rigid versions. Because of this, flexible ductwork is reserved for take-offs and usually limited to spans less than 15 feet to avoid as much temperature loss as possible.

Flexible fabric ducts are quickly gaining in popularity for open ceiling environments which tend to be in primarily industrial and commercial settings.

They are ideal because they allow a more evenly distributed airflow through multiple discharge points as opposed to single vent systems.

They can also be self-maintained rather easily since they are removable and can be washed in any large capacity washing machine.

While they may not have a high residential benefit yet, it is possible that the design can be modified over the next few years to be used in place of metal or plastic ducts.

Ductwork Maintenance

The easiest way to keep air conditioning ductwork clean, and the quality of air in a home at its best, is to ensure the air filters on your air conditioner are washed or changed at their proper intervals.

Traditional air filters are designed to be changed once a month.

Another growing market in the air conditioning industry is high quality air filter types, some of which promote increased allergen trapping capabilities, while others are simply designed to last longer than the usual one month increments.

With the proper ductwork design layout, effective combination of rigid and flexible ductwork, and proper maintenance procedures, air conditioners can deliver the highest levels of effectiveness at the lowest energy costs for many years.

HVAC Ductwork

Ductwork is the part of a central air system that carries both hot and cold air throughout the building. These ducts can be used to both bring air as well as remove air from a particular area.

Ductwork is an essential component of heating, ventilation, and air conditioning (HVAC) systems and is critical to proper function of the system as a whole.  A complete duct system is often referred to as ductwork.

Proper ductwork or duct work as it is also called, can vary widely depending on application. For example, when running duct work in a home, there are a very different set of standards than when running ductwork for a commercial application.  

Not only are the standards different but the type of material used is totally different as well. Let’s go over a few main points for both residential ductwork as well as commercial ductwork.

Residential Ductwork

In order for an air conditioning unit to work properly and efficiently, it must have a properly designed ductwork system connected to it.

The ideal duct layout will ensure that the appropriate amount of hot or cold air is being pushed into each room dependent on the room’s size.

Larger ducts are laid out to lead to rooms with greater square footage, while smaller ducts will be run to bathrooms and other smaller areas.

When dealing with residential ductwork designs, these factors must all be taken into account when installing the central heating and cooling equipment.

Residential Ductwork Design Factors

Even before the ducts can be laid out, the air conditioning unit itself must be placed in a somewhat central location that will allow the easiest access to the larger rooms needing more airflow.

If the unit is placed to far from the main living areas, more energy is required to heat or cool these larger spaces and longer ducts are needed to reach them.

As the length of the duct increases, the amount of potential temperature loss or gain increases as well, reducing the units effectiveness.

Another major factor, that can also be somewhat of an obstacle, is the layout and design of the house itself. The amount of attic space available to run the ducts, portions of the house have limited access space, or even spots that are blocked or obstructed can all pose ductwork design challenges.

These obstacles can usually be overcome adding flexible ductwork to the overall design, allowing the ducts to reach into smaller spaces inaccessible with standard rigid ducts.

One of the most overlooked items when laying out ductwork systems is ensuring all of the duct connections are properly fitted together to avoid any air loss.

This is a key factor at take-offs, or sections where smaller ducts are branched off from the main duct connected to the air handler.

Ducts should also be properly insulated in areas where they will be exposed to unregulated temperatures, especially in attics.

These are the key factors that must be taken into consideration when designing a residential ductwork layout. Having a properly designed ductwork system can help maximize your air conditioning unit’s effectiveness while keeping operating costs to a minimum.

Commercial Ductwork

Commercial ductwork usually consists of hard aluminum enclosures that are generally very rigid. These ducts carry air from multiple furnaces or AC units and allow for an even air distribution through vents all over the building.

Properly laying out the ductwork is essential in both of these situations.  This article will be expanded to cover this topic in much more detail in the very near future.

Flexible Ductwork – The Basics

Traditional air conditioning ducts are made from thin sheets of aluminum formed into tube like shapes and then coated with insulation.

There are also rigid insulation boards that can be used to form ductwork without the need for the sheet metal to hold their shape.

These two types of rigid ducts are ideal for main lines coming off of the air handler, but for smaller duct lines running to individual vents, flexible ductwork is often better suited for the task.

What Is In Flexible Ductwork?

As opposed to rigid sheet metal, flexible ducts are made with a coiled wire frame surrounding in a thin plastic or polyester sheeting. The wire frame allows to duct to hold its round shape while also allowing a greater amount of flexibility than traditional rigid lines.

Once the wire frame has been coated in plastic sheeting, it is then insulated with either a thick glass wool or a combination of glass wool and polyester fiber.

Once the ductwork has been properly insulated, it is then coated with a layer of polyethylene, another plastic substance with mostly industrial applications.

How Is Flexible Ductwork Used?

While the flexibility of ductwork is needed at times, most duct systems will not rely solely on flexible ducting due to its decreased efficiency when compared to rigid ducts.

Instead, flexible ducts are used in conjunction with rigid systems, often found connecting main lines to individual vents.

Usually potable air conditioning or heating systems don’t need venting, but sometimes they do. When ventilation is necessary, it’s best to use a flexible duct work system.

Branching flexible lines off the main fixed duct in order to reach rooms through tight angles or small spaces becomes much easier than trying to form a rigid line in the same manner.

Flexible lines also allow for future adjustments without the need to disassemble and reassemble a rigid structure.

In general, air conditioning installers will only use flexible duct work if the length of duct needed to reach the vent is under 15 feet. Even though the ducts are designed to be flexible, care must also be taken to ensure proper airflow is able to pass through.

While flexible ductwork may not be as energy efficient as rigid ducts, it works well as a component of an overall system when increased maneuverability is required.

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