Choosing the Best Ducting for Grow Room Ventilation or HVAC Setup

A topic that is usually only touched on briefly by most grow-room tutorials is the important role that ducting plays in your grow room; it is almost taken for granted. This guide on the best ducting for grow rooms will go in-depth on the subject to help you make an informed decision in choosing the best HVAC ducting for your space. 

The Role of Ducting in Your Grow Room Ventilation Setup

Air being evacuated by your fan into a duct requires duct tubes. These tubes act as a channel to prevent old, warm air from mixing in with the clean air in your grow room. For the best results, you’ll want your ducting to be kept at the shortest length possible with minimal bends.  

More bends translate to more work for your fans, causing a decrease in airflow. The general rule of thumb is about a 10% reduction for every 30° angle, though you will want to avoid any sharp bends. 

If you must make 90° turns, consider using two 45° turns at some distance apart, as this will be slightly more efficient. It’s even better to use rounded bends with a large radius.

Overall, more length means more friction as the air passes through the duct, which slows down the air. Exactly how much friction is dependent on the ducting material and the internal condition (whether it is dirty, kinked, or torn).  

Why You Need Flexible Ventilation Ducts in the Grow Room or Your Home

When considering the best HVAC ducting for your grow room, it may be tempting to consider rigid materials. Certainly, there are advantages to rigid sheet metal, such as increased airflow and thickness, but they tend to lack flexibility. 

Flexible ventilation ducting is usually made from aluminum foil layered with plastic film and sometimes coated with PVC for light proofing. Flex air ducts offer the benefit of being cheaper than other forms of ducting. The aluminum is also resistant to mold and bacterial growth, which is a key factor in maintaining air quality. The flexibility of the duct makes it easy to install in hard-to-reach places and is a far easier install for non-professionals.

Key Factors to Consider When Choosing the Best Ducting for Grow Room Ventilation

So, what is the best HVAC ducting to use in your space? When making your selection, there is a wide variety of ducting materials and styles to choose from. To help you decide, consider the four key factors outlined below. 


This is the most important thing to consider when installing ductwork. The most common size ranges from four to eight inches, though larger ten and twelve inch ducts can be required for higher-powered systems. Six inches is normal for smaller applications.  

If your ductwork is too large, your system will lack efficiency and cause the air to spend more time in the duct than it needs to. On the other end, undersized ductwork increases static pressure, which may create a noisy environment due to increased air turbulence in the duct and the reduction in the air flow generated by the fan. 

As a general rule, your ducting diameter should match the diameter of the fan and other equipment that it connects to. While you can use a smaller or larger fan with different-sized duct, you will need to get an additional accessory, called a duct reducer or a duct adapter, for this setup. 


Ducting can come in several varieties. While aluminum foil and sheet metal are the most common, there are other types of materials such as fiberboard and fiberglass. Fiberboard and fiberglass come with the advantage of insulation and noise reduction, but they can become contaminated by bacteria and mold. However, they do not make for the best HVAC ducting. Aluminum foil is the most popular solution for successful growing systems thanks to its lower cost and the ease of installation. 


Despite a potentially higher cost, insulation has several advantages. Metallic ducting can get loud, and insulation affords noise control. In addition, some types of insulation provide potential thermal benefits.  

Insulated aluminum also offers installation benefits. To ensure maximum airflow, it is necessary to stretch the ducting to smooth out the wrinkles and coils on its surface. Because of this and the thinness of the material, it is easy to puncture it. 

Light Proofing

When using ducting inside your garden, you should be aware of light leaks from the ducting. Light leaks can cause problems during the dark portion of the day during the flowering stage. This may cause the plants to start producing seeds or delay the plant’s readjustment from the vegetative stage to the flowering stage.

To address light proofing concerns, TerraBloom offers a variety of flexible ducting with black or white PVC coating on the external surface of the duct, which effectively blocks any light that might be present inside the duct. PVC layer also helps to add sturdiness to the duct structure and prevent punctures from external objects.

Where to Find the Best Ducting for Grow Room Ventilation or HVAC Setup

For all your ducting needs, TerraBloom offers flexible ventilation ducts with white and black PVC overcoats. Our ducts come in 4”, 6”, 8”, 10”, and 12.4” inside diameter sizes, making fitting them over similar-sized equipment much easier.  

Often ducts are tight with not enough slack in the diameter of the ducting. The ducts have 2-3 mm of slack for an easier fit, giving you greater flexibility in your installation. The PVC coating means that you won’t have light leak issues in your grow room.  

We also offer duct clamps with each duct we sell to make installation easier. Our ducts are offered in 8-foot and 25-foot lengths, and if you need to resize your duct to make it shorter, our products can safely be cut using metal snips without compromising the integrity of the duct. 

In addition to cannabis growing environments, our ducts can also be used in household applications. They are the best HVAC ducting solution that you can use. They can be utilized to build intake and exhaust air lines for any ventilation purpose that does not require the use of heat-insulating materials, such as connecting a room that is not managed by central AC or furnace to the outside.  

Our ducting can also be used to vent kitchen appliances to an outdoor space or to build an air exhaust line for a room with laser engraving or 3D printing equipment. Projects involving heat or cold insulation will require it to be purchased and mounted separately.  

Along with the best ducting for HVAC, TerraBloom also offers everything you need for a ventilation setup for grow tent, including intake fans for grow room, and the best inline fan on the market (see our resource what is an inline fan for more information). 

Wrapping Things Up

So what is the best ducting for grow room? Flexible ventilation ducting is the best choice for your grow room due to its cost-effectiveness and flexibility. When purchasing flexible ventilation ducts, consider the size of the duct alongside the size of your fan.  

TerraBloom offers the best choice in material for ducting, and our PVC-coated pipes will take care of any light leaks that may threaten your growing operation. We have the best ducting for HVAC you need for your grow room, and we can offer you everything else for your ventilation systems, whether you require an inline booster duct fan, an air carbon filter, or commercial inline exhaust fans.

Hopefully, this guide has given you some insight into choosing the best ducting for your HVAC as you put together your grow room’s ventilation system. Check out our website to browse the rest of our collection. In addition, the guides on our blog are sure to offer you new ideas to implement in your growing space. 

Shop at TerraBloom for all of your ventilation needs today! 

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