Operation of the SES100 Series Controllers
Traditional grow room climate controllers include a thermostat and humidistat wired to turn on an exhaust fan when the temperature and humidity rise above safe levels. This type of simple control is fine during the day, but at night (when the lamp isn't on) the exhaust fan may only run at the beginning of the night as the humidity levels increase due to falling temperatures. So for most of the night the vent fan is off, even though the plants still require fresh air. Adding a timer to the thermostat and humidistat solves this problem, by insuring a fresh air exchange.
But what if the garden uses supplemental CO2? Running the vent fan when CO2 is being released is a terrible waste of precious gas. Also the CO2 must be off at night, because plants do not require increased CO2 then. For the most economical use of CO2, the gas is released just after the vent fan turns off in order to quickly recharge the room, but must turn off 10 minutes prior to the next fan cycle. The SES100 series includes all of the logic necessary to efficiently add CO2.
FAN AND CO2 TIMER
The heart of the controller is a repeat-cycle timer with independent fan and CO2 stages.
- The REPEAT INTERVAL dial set the amount of time between cycles.
- The FAN DURATION dial sets how long the fan runs for each cycle
- The CO2 DURATION dial sets how long the CO2 is on for each cycle.
Once every cycle (set by Repeat Interval dial) the fan turns on and refreshes the room's air by exhausting the old, stale air. After the Fan Duration cycle ends, the CO2 stage recharges the room with fresh CO2. At the end of the CO2 stage, the CO2 outlet is turned off and the system waits for the next cycle.
CO2 CONTROL OPTION
Purchase the model 1050 CO2 monitor, plug it in to the SES100 controller and the unit is instantly converted into a complete CO2 control system. The CO2 outlet is turned on only as needed, and is turned off 10 minutes prior to the next fan run cycle, or when the fan turns on due to the humidistat or thermostat.
LIGHT SENSOR
A photocell senses light levels and allows the CO2 relay to turn on only during the day.
THERMOSTATS
The thermostats interrupt the timer cycle whenever the room's temperature rises above the set level (setpoint). After the fan turns off, the CO2 stage begins, but only during daylight hours. The solid state temperature sensor is mounted outside of the box to accurately measure the air temperature. The thermostat has a built in differential of 3º that prevents the vent fan from rapidly cycling on and off. The differential works by keeping fan off until the temperature rises above the setpoint by 1.5º. When the vent fan turns on, the differential then keeps the vent fan on until the temperature drops to 1.5º below the setpoint. There are separate day and night temperature settings that can be used to control the growth of the plants.
HUMIDISTAT turns on the vent, which runs until the humidity falls to correct levels.
Pump Timer (SES150 only) An independent interval timer is included with the SES150, and has separate interval and duration time settings.
TYPICAL CONTROL SETTINGS
- INTERVAL: 1 hour (cycle repeats once every hour)
- FAN DURATION: 5 Minutes (Exhaust fan run time depends on the fan and grow room size, and is set to allow the fan to provide a complete air exchange)
- CO2 DURATION: 7 Minutes (CO2 release time depends on the CO2 flow rate or generator size and the room size).
- THERMOSTAT: set to around 85° F, or as high as the plants can tolerate without suffering heat stress.
- HUMIDISTAT: generally set to 70-75% rH.
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