Metal Duct and HVAC Sheet Metal Ductwork Manufacturer in China

Metal Ducting: The Ultimate Guide

A metal ducting is a section of an air management system, which form passages in heating, ventilation and air conditioning systems (HVAC systems).

Depending on their exact locations, metal ducting can remove or deliver air in a room or system.

Here is exactly what am talking about:

Stainless steel ducting

Of course, there are other options.

And today’s guide explores all the basic and advanced aspects of the metal ducting system.

Let’s get started:

Advantages of Metal Ducting

The following are the advantages you gain from using metal ducting:

Stainless steel spiral duct

Long Lasting

Metal ducting offers a long-lasting ducting system for your application when you compare to other ducting systems.

This is because it is not easily affected by external factors such as climatic conditions.

Metal ducting especially the galvanized type is durable for various applications.

Low maintenance cost

Another benefit of using metal ducting is that it has a lower maintenance cost than the other types of the ducting system.

The rigid structure and their strength make these ducting system tough, which ensures they don’t easily tear up.

You, therefore, don’t have to incur replacement cost due to them breaking, which reduces your maintenance costs.

Standardization

Most manufacturers of metal ducting system fabricate standard products.

The advantage of this is that you can select a given metal ducting system that will fit your application without having to worry about the different brands available.

Disadvantages of Metal Ducting

The limitations you will experience when using ventilation ducting systems include the following:

Relatively Expensive

Metal ducting is quite expensive when you compare to flexible ductwork due to its favorable characteristics.

This includes it is long lasting, and it does not react with moisture easily to prevent airflow.

Higher Labor Cost

Metal ducting requires careful designs to fit perfectly on your application.

You will need a professional to do this for you, which means you will have to pay more for your labor cost.

Difficult to Install

Installation of metal ducting is somehow technical since there are several factors that you need to consider.

Improper installation may lead to your ductwork not functioning appropriately like having leakages.

As a recommendation, it is better you hire a professional to do the installation process for you.

Classification of Metal Duct

There are different types of metal ducts in the market.

You will find these metal ducts in the following classes.

1) Stainless Steel Duct

Using stainless steel ducts offers a wide range of advantages for your applications.

For starters, it offers a corrosion-resistant material that is not easily affected by factors such as water or air.

This helps in minimizing corrosion making your ducts durable.

Stainless steel duct

Also, you get an aesthetic appeal by using these ducts, which makes them easy to clean and maintain.

Lastly, it is the best metal duct if you are looking for a thinner duct that retains its overall weight.

2) Stainless Steel Spiral Duct

There are several advantages of using stainless steel spiral ducts.

First, you have a guarantee of a long-lasting metal duct since stainless steel is not affected by corrosion.

Stainless steel spiral duct

Also, the spiral aspect in these ducts minimizes connection points which have the effect of reducing any leaks.

If you are to compare the cost of installation to the other types of metal ducts, stainless steel spiral duct is cost effective.

3) Galvanized Duct

Galvanized ducts are ideal if you are looking for a metal duct that is relatively cheaper to buy and maintain.

It is also durable which ensure you get maximum service.

Galvanized metal duct

Galvanized ducts offer an easy inspection option when you compare with the other types of metal ducts.

However, there are certain limitations that you will experience when using this type of duct.

For instance, it is easily affected by chipping and cracking, which affects its quality.

4) Galvanized Spiral Ducting

Galvanized spiral ducting offers several advantages when you compare to other types of metal ducting.

For instance, these ducts utilize very little space since there is no use of reinforcements and connectors saving up to 3 inches of space.

Galvanized spiral ducting

Also, they are effective at minimizing air leakages, especially at the duct joints.

This has the effect of reducing energy consumption while increasing the level of efficiency.

Lastly, the overall cost of installation of this type of metal duct is cheaper than the other types.

6) Double Wall Spiral Duct

The fabrication process of a double wall spiral duct involves two solid metal sandwiching a fiberglass material.

Using this type of metal duct offers you several benefits.

Double wall spiral ducting

These benefits include insulation against energy loss, which reduces the cost of energy of your metal duct.

In cases of fire breakout within the duct system, the double wall helps in minimizing the spread of the fire.

Also, the double wall minimizes the noise produced by the metal duct, offering you a sound ventilation system.

6) Rectangular Duct

If you have a tight space that does not give room for other types of metal ducts, then this is a convenient option for you.

Rectangular duct

Rectangular ducts utilize very little height space, providing you with a convenient way of air conditioning your room.

Also, it is convenient for use in a low-pressure system

Recommended R-value for Metal Ducting Systems

The R-value refers to the heat resistivity of given insulation in a metal duct system.

The higher the resistivity value, the better the insulation material.

Two factors determine the R-value of a given metal ducting system, that is:

• Insulation mass in terms of the thickness and the density
• Compression ratio during the installation process

If the compression level is higher, then you will have a lower R-value.

An effective insulation material needs to be dense and thick.

A proper insulation material offers a good barrier between different temperatures minimizing unnecessary cooling or heating of your metal duct.

You can have different R-values for your metal duct depending on the type of your climate and the surrounding environment.

The following are the recommended R-value for metal duct systems depending on different climatic conditions.

Your professional should be able to guide you on the best R-value for your metal duct for the effective working of your metal duct.

Before insulation of your metal duct, confirm that you have sealed all leaks.

If there are any leaks, seal them using a foil tape while avoiding duct tape since it won’t last.

Choosing Material for Metal Ducting

When selecting a material for metal ducting, you need to consider several factors.

The factors you need to look into include:

 Metal duct material

Type of Application

The type of application will have an impact on which material you select for your metal ducting.

This is because different metal duct materials react differently in different environments.

Some of these reactions, like rust, ultimately lead to the poor working of your metal ducting.

You, therefore, need to select a material that won’t react negatively with the immediate environment.

Cost

Ultimately, you will have to consider the cost of the material you are going to select.

These materials have different prices based on the quality of service they offer.

A good material will be relatively expensive, but you have a guarantee of quality service.

However, if you work on a modest budget, you can still get a material though you will frequently have to replace it.

Corrosion Resistance

Your metal duct will always react with different environmental factors such as moisture and water.

It is therefore crucial that you check on the corrosion resistance of your metal duct before deciding on which one.

The best metal ducting system should be able to corrosion resistance against the external environment.

Mechanical Properties

Screwing your metal ducting within your application should be an easy process.

You, therefore, need to check on the ability of your metal ducting to attach on your application either through handing or screwing.

Difference between Flexible Ductwork and Metal Ductwork

While both the metal and flexible ductwork are vital in the installation of a proper conditioning system, there exists a considerable difference between them.

Such differences include:

Rigid duct vs flexible duct

First, the main material that makes flexible ductwork is plastic.

Different types of plastic such as PVC, PET, and PP are available for fabrication of flexible ductwork.

Each of these materials has its limitations as well as benefits, which affects the quality of given flexible ductwork.

On the other hand, the main material for metal ductwork is metal.

Here, you will find different metals are available for manufacturing of metal ductwork, including galvanized steel and aluminum.

The different types of metal materials result in different types of metal ductworks.

Flexible ductwork offers a more flexible option for your conditioning system than metal ductwork.

This is because most flexible materials, for instance, PVC are flexible and versatile.

Metal ductwork, which is also called rigid ductwork is necessary for installation points that don’t require much bending.

The materials that make metal ductwork are responsible for their rigidness.

Another difference is in the installation process.

Generally, flexible ductworks are easy to install when you compare to metal ductwork.

However, you need to be careful when installing the flexible ductwork to avoid leaving contractor error.

Such errors may increase your maintenance costs as well as your energy bills.

You will also notice that metal ductworks are quite expensive than flexible ductwork.

This is because metal ductworks are much durable than flexible ductwork.

Flexible ductworks are generally ideal for short runs in the branch and trunk system of your conditioning system.

This is because of the flexibility they offer.

On the other hand, metal ductworks are ideal for installation on the entire conditioning system since they are durable.

Metal Ducting Installation Process

The metal ducting installation process is a critical part of an entire ducting system.

It involves a few basics steps that you have to be careful to adhere to avoid improper installation.

 Fully installed rigid ductwork

These steps are:

Designing

You need to understand the basic layout of your metal ducting system before you begin the installation process.

Typically, this is a computerized process that determines the actual layout of your house as well as that of your conditioning system.

It helps in determining the size of the metal ducts, their location, and the different registers that you are to use.

Rough-in

After getting the design layout, the next step is the rough-in.

This step involves cutting various holes on the subfloors.

You will use these holes for installation of the ducts and registers.

You, therefore, need to ensure that the holes are of the same size as the registers and the ducts.

You will find the sizes of the ducts on the manufacturer’s manual as well as their location.

As a recommendation, the distance from the wall to the supply register holes should be around three inches.

Again, try to maintain the holes at the center between floor joists.

Remember, the return air holes usually are cut into the subfloor and then through the interior wall’s bottom plate.

Next, you install a plaster frame on the wall, which makes it easier to drill the drywall on return air hole.

Remember to mount the plaster frame around three inches off the wall top.

Installation

After cutting the different holes, you are now ready to do the installation part.

Start by installing the evaporator coil and the air handler.

Check on your manufacturer’s manual when installing for proper installation.

After that, attach the plenum to the evaporator’s outlet.

Alternatively, if you lack a central ac system, you can attach the plenum to the furnace.

Remember, the plenum is a small metallic box with one of its ends open and the other one closed.

After installation of the plenum, you can now install the take-off collars which are typically square in shape.

Do this by drilling a hole in the collar and then insert the tabbed portion through the hole.

Bend the tabs and use the screws to hold them in place.

Install the collars in such a way that ducts’ top which connects to them are beneath the floor joists’ bottom.

The next process is the installation of the metal duct’s main truck lines.

Here you connect the start collars to the metal ducts.

It is advisable to cut exact holes for the branch metal duct takeoffs on the top part of the metal duct.

Attach these branch ducts on the main duct’s top fitting them between the joists of the floor.

Occasionally, you install a transition whose function is to move from a larger size of the duct to a smaller one.

Support these ducts at intervals of eight feet using metal hangers.

Connection of the duct to each other is through the “drives” and “s” system.

The “s” refers to pieces of metals that you fold over themselves, making a slot for separating two duct ends.

Each end of a duct will slide to a different slot.

You can install these on the bottom and top of metal duct pieces.

On the other hand, “drives” refers to metal pieces that you fold over themselves sliding to the duct sides which holds them together.

Bend the drives’ tabs together after installing to hold them together.

Install end caps on the end of your supply ducts.

How to Cut Metal Ducting System

When cutting a metal ducting system, you need to be careful not to cause damage to yourself and the entire metal ductwork.

Here are a few factors that you need to take into considerations.

Rectangular ductwork

Prioritize Safety

Cutting metal ductwork can be a dangerous affair, especially with the sharp metal edges.

As such, you need to protect yourself by wearing thick and heavy work gloves that protect your hands.

Also, you need to wear safety goggles that protect your eyes.

Proper Cutting Equipment

To cut a metal duct into the shape and measurement that you require, you have to use the right cutting equipment.

For instance, a power saw that has special blades.

Take a Proper Measurement before Cutting your Metal Ductwork

Measurement is a critical element of the cutting process.

You don’t want to waste your metal duct while at the same time, you don’t want to have an incorrect measurement.

Use a correct measuring tape and if possible, take the measurement twice to be sure of having the accurate measurement.

Fasten Down Your Metal Ductwork before Cutting It

Before cutting your metal ductwork, fasten it down to prevent it from moving during the cutting process.

Several devices such as a vice are available for use when fastening your metal ductwork.

Cost of Metal Duct vs. Flex Duct

Basically, when you compare the cost of metal ducts VS flex ducts, you will find the cost of metal ducts being relatively higher.

This is because metal ducts are durable, and their installation process is somehow complicated.

The other factor that is likely to push the cost of metal ducts high compared to flex ducts is its energy-saving capability.

Metal ducts are energy saving ducts since they don’t easily leak.

Apart from these factors, other elements that are likely to push the cost of your metal ducts high are the designing and installation cost.

Also, the size of the metal ductwork will determine the cost that you will pay.

Metal Ducting Fittings

There are certain accessories that you need to accompany your metal ducting fitting for its proper functioning.

Such fittings include:

Metal duct Elbows

These are fittings that you will require when installing your metal ducting in low pressure or low-velocity environment.

They are ordinarily right-angled in shape.

Metal Duct Bends

These fittings are essential when you want to reroute your ductwork by the right angle.

Its inner clearance varies along the bending path of two planes.

Metal Duct Eccentric Reducers

The function of these reducers is to reroute the metal ductwork, especially when there is a modification on your metal duct.

Metal Duct Transition Piece

Its function is to help in changing the shape of the ductwork from either round to rectangle or rectangle to round.

Alternatively, you can use it to change the shape of your ductwork from either round or rectangle to square and vice versa.

Metal Duct Offsets

You can use these metal duct fittings to bypass any obstacle along the route of your ductwork. Such barriers can be two ducts intersecting.

How Metal Ducting Works

The basic working of metal ducting involves the flow of warm air from the room to the outside and clean cold air from outside to the inside.

However, the process is somehow complex than this since there are other parts of the metal ducting involved.

Cold air from the outside flows into the metal ducting via the air blower.

Here, there is regulation of the amount of air that flows into the ducting system.

Vibration isolators present here functions to minimize vibrations that produce unnecessary noise.

Typical HVAC System – Photo courtesy: STEEMIT

As air flows through the air handler, there are takeoffs that branches depending on the size of your room.

The takeoffs supply air to the various rooms in your building.

The diffusers present here helps in reducing speed while increasing pressure within the takeoffs.

There are volume control dampers which help in controlling the volume of air flowing into the various sections of the system.

Depending on the type of your metal ducting, the volume control dampers can either be manual or automatic.

To minimize the spread of fire within the duct when it occurs, most metal ducting’s’ have fire and smoke dampers.

As air flows through the metal ducting, there is a need for it to flow smoothly and in the given direction.

You achieve this through the availability of turning vanes.

The positioning of these turning vanes is at a right angle to reduce turbulence and airflow resistance.

Once air flows into the room, the warm polluted air has to flow out of the room.

This happens using the plenums that direct air from the room into the central air handler.

Your metal ducting can have several plenum depending on the number of rooms you have in your building.

Also, you need to note that there are two types of plenum in any metal ducting system.

There is the supply plenum which directs air from the takeoffs to the different rooms present.

Then, you have the return plenum that directs warm air from the room to the takeoffs from where it flows to the air handler.

From the air handler, the warm air flows to the exhaust air inlets and out into the atmosphere.

By doing this, you can condition your room.

It is vital to note that at no single point during the conditioning process that there is no mixing of the two types of air.

Part of the reason is air from the room is warmer hence lighter in density than the cold air from the outside.

Remember, you can control the level of conditioning for your room through the use of the control buttons.

Uses of Metal Ducting Systems

You will find a metal ducting system in a wide range of applications.

These applications include:

Section of HVAC System – Photo courtesy: HUFFPOST

Food and Agriculture Industry

The function of metal ducting in the food industry is to ensure proper air conditioning.

Here, dusty and warm air flows out of the industry through the metal ducting while cold air flows into the industry.

This ensures there is proper circulation of air which offers convenient production and storage environment.

Construction Industry

Another use of metal ducting is in the construction industry.

Companies such as cement manufacturing use these ducts to offer convenient cement production capacity.

This happens by pumping dusty air from the company and directing it to a dust collector while fresh air flows to the industry.

Carbon Dust Collection

You will also find metal ducting an essential aspect in factories where there is a lot of carbon emission.

To minimize environmental pollution, these ducts are used to direct carbon flow into a collector while allowing fresh air to flow into the company.

The carbon collected is discharged periodically in an environmentally friendly process.

Air Conditioning at Residential and Commercial Properties

Lastly, the metal ducting system is of everyday use in residential and commercial properties in providing proper air circulation and temperature.

This is by allowing clean air into the property while extracting warm polluted air from the property.

Regulation of temperature is through allowing the flow of cold air from the outside while removing the warm air into the environment.

Conclusion

There you have it, all the information that can guide you when selecting your metal ducting.

Of noteworthy is to consider the several factors necessary before choosing a particular material and type of metal ducting.

If you still find any problem on your metal ducting system, get in touch with us today.

Our team of experts will offer you professional solutions.