oh and for all who are wondering the telaire ventostat is meant for automated building ventilation controls, for instance, it is used in parking garages to control ventillation fans when CO2 levels get too high (initially set at 1000ppm but they can be adjusted). In their original use they would be basically wired to control a vent fan to keep ppms from building up over 1000 but not run the fans much below 1000 to save power since its within OSHA guidlines.

Anyways, we growers take the sensors and wire the output to a solenoid on a co2 tank.. so when the sensor detects CO2 levels are below 1000ppms (we reprogram it to 1500ppms but stick with me here) it sends a signal to turn OFF the fan (it thinks its hooked up to) but it actually opens the co2 valve flooding the room. When it senses the room CO2 level is back to its programmed maximum it sends the signal to turn on the fan it thinks its hooked up to (which shuts off the CO2).

It is made by GE and its quality control is somewhat regulated by OSHA saftey standards.. therefor I would give it a decent chance of staying accurate.

Keep an eye out for these because just like I found one sometimes they are just reguarded as another useless sensor.. but with a quick trip to radio shack its going to play a vital role in my atmospheric control system that would have cost over $500 if i bought an all-in-one c.a.p. system.