Grow Room Intake and Exhaust Setup

Ventilation is essential to any grow room delivering an optimal yield and potency. All growers want to get the most from their setup, and your intake and exhaust are integral to air flow and circulation.

Temperature control, transpiration, humidity regulation, and odor control all rely on a sealed system with the right intake fan and exhaust for the size at hand.

Here we’ll be taking you through a look at the best grow room intake and exhaust setup advice so that your plants produce potent heads and a high yield throughout the year.

The Importance of Regulating Air Flow

The Importance of Regulating Air Flow

The temperature and humidity in your indoor garden need to be moderated with a good ventilation system. Plants need fresh air to thrive. With each 1000-watt grow light lifting the temperature between 10° and 15°, ventilation is essential. When choosing your equipment, consider whether you’ll be including a thermostat to switch the ventilator on and off automatically. Otherwise, you can maintain constant circulation at a limited rate of flow.

Passive or Active Intake

Systems which don’t use an intake fan to bring in a supply of fresh air are called passive systems. They typically have an exhaust only, and a few standard oscillating pedestal fans blowing a steady breeze. You also have the option of a negative pressure setup where an intake hole or duct brings air into the room based on the negative pressure inside; there is no need for an intake fan. Most conventional setups use an intake and exhaust fan, along with a carbon filter or two to guarantee clean, odor-free air.

Intake Fan Positioning

Position your intake fan either at ground level or as near to it as possible. Make sure that your ducting is straight and always secure the duct with duct tape. Make sure that your CFM has been calculated with the length of duct connecting to a source of fresh air (i.e. a window or vent) factored in. The higher the volume the higher the CFM.

Ducting can be concealed by building a box around it, around your window frame. Conduit piping can also hide it quite well, and creative solutions shouldn’t be too hard to think up as long as you don’t use a massive distance of duct piping to reach fresh air.

Exhaust Fan Setup

Your ducting needs to match your grow tent box or room perfectly. If you don’t have an exact match then use the appropriate reducers with clamps and duct tape to seal any connections. You want the passage of air to be pulled from the intake at the bottom of your setup upward across the grow lights where the air is most directly heated. Your exhaust/extractor fan should be suspended from the roof. If you are going to be using a carbon filter on your exhaust fan, suspend it as well or make sure you’ve got enough CFM and put your filter on the floor before running ducting vertically to the exhaust fan.

Remember, hot air rises. As the air in the environment starts to warm and become stale, your exhaust fan needs to be ready to capture it, and the air needs to be flowing in that direction. When you’ve got negative air pressure on your side thanks to a sealed system, this is relatively easy.

Sealing the Exhaust System

It is extremely important to make sure that your exhaust system is completely sealed; this is the only way to guarantee its efficiency. Without a sealed exhaust system, not even carbon filters will stop odors. You also put your plants at risk of mold and other air pollutants when they’re a gap in your suction. Even when using a dual fan setup, you can still build for negative air pressure. Doing so creates suction as soon as the exhaust fan is switched on.

Seal the whole grow space and leave the intake and exhaust exposed. If you do this right, you should see the smoke of an incense stick, match or cigarette get pulled into the intake as soon as it is held there.

Sealing the Exhaust System

The Total Setup in a Nutshell

The basic configuration to keep in mind is an intake fan set low which is attached to a carbon filter, with the air flow positioned to flow across the passage of a grow light (or lights), then led via ducts to another carbon filter, and finally to your high-positioned exhaust fan which then leads outside.

There are many variations to this grow room intake and exhaust setup, but this is the basic premise that’ll keep your air clean, plants healthy, humidity regulated, pests away, and it’ll also make sure that no one catches a whiff of your cannabis.

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  1. Thanks, I’ve recently been playing with a grow room idea and looking for information about this topic. I discovered your site and some really useful info on equipment. Getting the rigging in place, noise and the size of the fan are all details that make this more involved than I thought.

    • Hi Zachariah, I understand the dilemma. A few details to think about, but take it a step at a time. If you are setting up in a basement it will be a bit different than say using an attic space or a spare room. You want to think about whether you want to use a grow-tent and I think that is a good idea so you can control conditions well in an area for your plants and also contain odor (depending on the strain). You left your comment on this post about intake and exhaust setup so I gather you are worried about the sort of fan you will need and ducting. You also want to think about a carbon filter if you are in a built-up area and need to control the odor. Look at the area of your tent first and then work out what sort of CFM rating you need on your fan. We give some good suggestions on posts where we reviewed fans, so check those out, and I would suggest perhaps reaching out to the helpdesk for a brand and doing a quick check with them that the fan is not too large or small in capacity for the space you are managing. When I do projects like this I tend to go down to the local hardware barn and look at ducting and what they have to get ideas on how to fit all the parts together inline and how to anchor/support the system. Don’t forget that you might need to get a thermometer and humidity reader for your grow-tent too as you need to balance lighting, water and airflow to try and get the optimal conditions. I would also suggest a hydroponic system. If you can get all of it worked out, then you should get as much as twice the yield against growing in soil outside by comparison. Quite a bit of mucking around at the start, but once set up, the rest is plain sailing.

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