Maintaining the correct temperatures in your grow room is essential for your plants to thrive and large fluctuations can slow the growth and yield from your crop.
When your lights are on you can use fans to supply fresh air and remove the heat, but when your lights turn off it is a different matter.
Cold air can passively travel through your inlet ducting and will lower the temperature considerably inside the room. A heater can be used to raise the temperature but it requires additional costs to run, so a much cheaper option is to use a back draft shutter.
Back Draft Shutters can be installed into your ducting near the inlet and outlet holes of your grow room, and will control the air allowed to enter and escape when your fans are off.
Two aluminium blades are fitted internally and they have a spring fitted to hold them closed whilst your fans are off. When your fans turn back on, the pull of air will simply open the blades and allow the air to flow easily through your ducting.
These are great for grow rooms or tents that get cold at night and they will seal your ventilation holes automatically when your fans turn off, to keep your temperatures adequate and any odours from escaping.