TrolMaster BETA-8 Digital CO2 Controller | NDIR, 400 to 2000 PPM

How This TrolMaster CO2 Controller Measures and Switches

The sensor type is the first thing worth checking on anything that claims to read carbon dioxide. This one is NDIR, which stands for nondispersive infrared, and it works by measuring how much infrared light the gas absorbs across a path. That is the method used in laboratory instruments rather than the chemical cells found in low cost monitors. Accuracy is plus or minus fifty parts per million. The control range runs from 400 PPM, which is roughly outdoor air, up to 2000 PPM. Deadband is adjustable between twenty and two hundred parts per million. That setting decides how far the level drifts before injection restarts. A narrow band gives frequent short bursts, while a wide one gives fewer and longer ones. The sensor sits on a remote lead of sixteen feet so it can hang at canopy height rather than beside the controller. Output is a relay rated at ten amps on a 120 volt supply, with a six amp fuse behind it.

The Photocell, and Sizing the Relay Against a Generator

A photocell built into the remote sensor head handles the day and night switching. When it sees darkness, injection stops, because a plant in the dark is not fixing carbon and gas injected then is gas wasted. No timer is needed and nothing has to be wired to the lighting circuit. There is a consequence to that convenience. The sensor head has to be able to see the room light. A probe tucked behind a fan housing or under dense canopy will read night while the lamps are on, and injection then never starts. Hang it where it sees both the canopy air and the light. The sizing question comes next. Ten amps at 120 volts is ample for a regulator solenoid and it covers many small burners. A large generator or a multi-burner assembly needs its draw checked against that figure first. The body measures 130 by 78 by 46 mm and the power cord is 1.8 m long.

Key Features

• Sensor: NDIR, which is nondispersive infrared rather than a chemical cell
• Accuracy: Plus or minus fifty parts per million
• Control range: Four hundred up to two thousand parts per million
• Deadband: Adjustable from twenty to two hundred parts per million
• Remote sensor: On a sixteen foot lead, so it hangs at canopy height
• Photocell: Built into the sensor head, stopping injection in darkness
• Placement caution: A sensor that cannot see room light will read night all day
• Output relay: Ten amps, with a six amp fuse behind it
• Input: A hundred and twenty volts AC, on a 1.8 m power cord
• Body size: 130 by 78 by 46 mm

Technical Specifications