Growing Tips

Air Cooled Lighting

grow light bulb

As temperatures increase in the summertime, the heat produced by lighting systems becomes more of a problem. Air-cooling these systems can become necessary.

How do Air Cooled Lighting Systems Work?

Air cooled reflectors use a glass bottom to create and airtight tunnel. Cool air is blasted through it, past the face of the lamps, taking away the excess hot air with it and cooling the lamp surface. The plants below still get the benefit of the light, but without suffering the effects of excess heat.

Be sure to keep the glass surface clean, however, as this is where beneficial light might be blocked or reflected by dust or moisture build-up on the glass surface.

Benefits of Air Cooled Lighting Systems

Removing heat with an air-cooled system prevents heat build-up in the summer, especially among the plants closest to the light sources. Lights can also be places closer to plants without burning them – this can become a factor especially as the summer season lengthens and plants grow higher, closer to ceiling-mounted lights. Small grow rooms, like those made in closet spaces, are especially susceptible to overheating, and a cooling system can save your plants from total destruction. It also reduces the strain on your ventilation system and can help to increase CO2 levels without having to add any through artificial means.

Common Misconceptions

There are a lot of myths around air-cooled light systems, so let’s address them directly.

Bulb Heat Is Lost

This is not quite accurate. HID lamps produce two types of heat when they are on. The first is convection heat. Air moving over the surface of the light can greatly reduce this form of heat by moving it away, down the duct, as it conveys the heat. In effect, it releases the heat at a destination outside of the grow room, where it otherwise would have been conveyed into it.

The second is radiated heat. Radiated heat moves in waves through the glass and into the room. Moving air past it does not significantly reduce radiated heat.

Air Cooled Reflectors Are Better Because They’re Closer

This is true in most cases – but keep in mind that the closer the reflector is to the tops of your plants, the more focussed the light is. If you want to cover a wider area, lifting the light may be of greater overall benefit than dropping it close. Aim for the optimal light levels at the plant surface: 800-950 micromoles/s.

Light Is Lost Through Glass Panel

High-quality, flat glass that is well-suited to this purpose will drop light efficiency by as much as 4-5%. This is less a factor than the loss of light produced when lamps are raised up higher to prevent overheating. Of the two options, the cooling system actually results in more light reaching the plants. Keeping the panes clean and the reflector closer to the plants will give best results.

Colder Air Blown Through Is Better

This is accurate, but the gases in the lamp’s arc tube need to be at the appropriate temperature to produce the optimal amount of light too, so overdoing it will create losses along with any intended benefits, and they will cancel each other out. The purpose of an air-cooled light is to remove excess heat, not to decrease as much heat as possible. It is about balance. A good rule of thumb is to use cooling air of a similar temperature to that in the grow room itself. This will also prevent the build-up of condensation or fogging on the glass, allowing for all of the available light to continue passing through the glass from the lamp and onto the plants below.

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