St0ney

This scheme (above) is used to cool a HID light when the space is CO2 enriched. Outside air is ducted into the HID reflector (with a lens) and pumped out with a commercial grade blower (blower #1 above). This blower is controlled by a thermostat (controller #1 above) set at 85 F, which is an excellent temperature for CO2 enrichment. If the space temp. drops below 85 F the blower is shut off and the light heats the room. When the temp. rises above 85 F the blower turns on and the HID heat is vented.
A second blower is used to vent the air from the space itself. This blower (blower #2 above) is controlled by a combination humidistat and thermostat (controller #2 above). The humidistat is set at a reasonable level like 50 % to 75 % and the thermostat at 95 F. If the humidity rises above the setpoint the room's moist air is vented. This controller's thermostat is used as a safety in case blower #1 or controller #1 fail for some reason. If the room temp. rises above 95 F the room itself is vented. This defeats the CO2 enrichment but will save the plants until the problem is fixed.

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"A man's ethical behavior should be based effectually on sympathy, education, and social ties; no religious basis is necessary. Man would indeed be in a poor way if he had to be restrained by fear of punishment and hope of reward after death." -- Albert Einstein