Almost indispensable for indoor growing is an exhaust air system, which conducts used air out of the grow box or grow room so that fresh air can flow in (or is also supplied). Without carbon dioxide from the air, the plants cannot grow, so new air has to be brought in. In addition, the plants release water into the air through their leaves, so that the humidity in the growroom increases. Often, the grow lamps used lead to a rise in temperature in the growroom, as they heat up.
With an exhaust system, you get rid of warm, humid air and ensure that fresh air flows in so that the plants can breathe and grow.
What do you need?
Our exhaust air sets contain completely assembled components with which a grow box or a grow room can be ventilated accordingly. These always consist of an activated carbon filter that cleans the air, a tube fan that sucks in the air and an air hose through which the air is led out of the growroom.
How much power is needed?
The power of a tube fan is measured in cubic metres of air per hour (m3/h) that the tube fan can transport (convey). Due to the length of the air hoses used and the activated carbon filter, there is a pressure loss which reduces the amount of air actually conveyed. How much exhaust air capacity is actually needed depends on various factors such as the volume of the grow box or grow room, the power and type of light bulbs used, the ambient temperature, and many more.
Factors influencing the exhaust air performance:
- Volume of the growroom or length, width and height of the growbox.
- Ambient temperature and, if applicable, supply air system
- Type of light source: ESL, NDL/MH or LED emit different amounts of heat.
- In the case of NDL/MH: are air-cooled reflectors such as Cooltube or similar used?
- Number and wattage of the light source: How many lamps with how many watts?
- Length of the exhaust hose
- Is there a rising ventilation (e.g. via the roof)?
The rule of thumb for operating sodium vapour lamps is:
Room volume * 30 + Illuminance * 1/3 + Hose length * 20.
So if we have a grow box with a base area of 1 square metre and a height of 2 metres, it has a room volume of 2 cubic metres. With an illuminance of 600 watts and a 3 metre long air hose, the result is therefore:
2 * 30 + 600 * 1/3 + 3 * 20
60 + 200 + 60 = 320 m³/h
In this example, many of the above factors are not taken into account to keep it simple. The tube fan should therefore have a capacity of at least 320 m³/h.
Basically, we recommend tube fans that can be switched to two different output levels (low/high), or that adjust their output automatically by means of climate controllers based on the temperature or humidity.
For a grow box in the size 80 x 80 cm, for example, a performance of the tube fan between 187 m3/h and 360 m3/h is suitable.
Our guide values for exhaust air sets
Growbox 80 x 80 cm:
Ventilation set 160 ECO (145 to 187 m3/h) or
Ventilation set 250 PRO (220 to 360 m3/h)
Growbox 100 x 100 cm:
Ventilation set 250 PRO (220 to 360 m3/h)
Growbox 120 x 120 cm:
Ventilation set 250 PRO (220 to 360 m3/h) or
Ventilation set 800 PRO (420 to 800 m3/h)
Our exhaust sets are also available with particularly quiet running "Silent" tube fans from Soler & Palau, and they are of course an indispensable part of our grow kits.
For the set-up of exhaust air sets we have a short instruction as PDF: Installation instructions for exhaust air sets.
