Air cooling

Dear Ed,
I’m going to be growing in a 7 x 13 foot room on a 4 x 6 foot table with two 600w HPS lamps. I am going to supplement the room with CO2. The room has a 1.5 x 2.5 foot window. How can I control the heat under the lights that is going directly on my garden? With enriched air can I bring in fresh air from outside constantly or should I have air brought cyclically? If I bring in fresh air do I need to vent out the old air?

Mad scientist,

Air-cooled lights are used to control the heat directly under the lamps. These lamps have a glass plate at the bottom of the reflector so light can get through but the heat is enclosed. Two 4-inch flexible air tubes, one on either side of the reflector respectively, push unheated air in and exhaust out the lamp-heated air. A small fan installed inside the tubes pushes the air through. This eliminates much of the heat under the plants and in the room. The heated air, which is odorless because it was never in the grow room, is exhausted into a space which needs heating, or vented outside.

In gardens in which the air is enriched with CO2, it is best to keep the same air in the room to preserve the high levels of CO2. But even with air-cooled lamps, the room can heat up, and if the room is ventilated, the new air must be enriched.

One way to solve this problem is by using a window-mounted or portable air conditioner. These units cool the air in the room but do not replace it. As long as the air is enriched, cool and not too humid there is no need to ventilate more than once an hour.

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