A typical installation consists of a circuit breaker box, relay/transformer box and a GHK12x2. The circuit breaker box provides overload protection. The relay/transformer box switches line power to the appliances. And, the GHK12x2 senses temperature and provides control signals.
BE SURE ALL POWER IS OFF BEFORE INSTALLATION!
INSTALLATION SHOULD BE DONE BY A LICENSED ELECTRICIAN.
BE SURE ALL WIRING AND EQUIPMENT IS INSTALLED ACCORDING TO LOCAL ELECTRICAL CODES.
THE GHK12X2 IS A LOW VOLTAGE DEVICE. THEREFORE, VOLTAGES INSIDE THE BOX MUST BE LIMITED TO 24VAC CONTROL VOLTAGES.
CAUTION: The GHK12X2 is designed to be reliable but as with all equipment, failures do occur. Therefore, in situations where loss could result from the failure of the GHK12X2, separate backup thermostat or alarm systems should be provided.
The reliability and performance of the GHK12X2 can be compromised by locating the controller in direct sunlight or in direct water spray.
Mount the GHK12X2 in an easy-access location. Usually close to the breaker box and relay box. Protect it from direct sunlight for better reliability and readability. Moisture can cause corrosion and premature failure, so avoid direct water and have all wire enter and leave through liquid-tight connectors, waterproof conduit, or seal the wires with silicone sealant.WARNING: Some sealants release acetic acid while curing. Be sure sealant is completely cured (up to 3 days) before closing control box to avoid corrosion damage.
To mount the GHK12X2, remove the front cover and unplug ribbon cable from the relay board. Insert the 4 drywall screws provided with the GHK12X2 through the 4 corner holes and fasten the box to the wall. After all wiring is complete and any sealant cured, reattach the ribbon cable and screw the front cover on.
| OUTPUT | CONTACT TYPE | VOLTAGE RATING | CURRENT RATING |
| HEAT | OPEN/CLOSED OR SOURCE 24V AC | 24V AC | 2A RESISTIVE LOAD |
| COOL HAF TIMER |
SOURCE 24V AC | 24V AC | 2A RESISTIVE LOAD |
| ALARM | OPEN/CLOSED | 24V AC | 2A RESISTIVE LOAD |
All cool, horizontal airflow (HAF), and timer outputs source 24V AC to drive a relay or contactor. The GHK12X2's drive relays are rated at 2A when driving a resistance load. For reliability snubber circuits are on each output. Also, for greater reliability, load currents on the GHK12X2's relays should be less than 1A (less than 24V A per output).
In 2-zone mode, outputs cool 1 and 3 are designed to open the vents. Outputs cool 2 and 4 then control the fans. There is a 30 second delay between cool 1 (cool 3) activating and cool 2 (cool 4) coming on to ensure the vents are open before the fans start. In single zone mode, cool 1 is used to open vents, cool 2 and cool 3 for fans and cool 4 for additional fans or pad cooler.
The HAF 1 output is the normally closed side of the cool 2 relay and HAF 2 is the normally closed side of the cool 4 relay. Therefore HAF 1 (HAF 2) is off when the cool 2 (cool 4) fan is on and HAF 1 (HAF 2) is on when cool 2 (cool 4) is off. With a jumper setting, the HAF 1 contacts can drive the HAF terminals for switching from 2 zone to 1 zone.
The heat outputs can be configured as an open/closed contact like a thermostat or to source 24V AC to drive a relay. Open/closed contacts is the factory setting.
Jumpers shown for heat 1 and heat 2 are configured as open/closed contacts.
Jumpers shown for heat 1 and heat 2 configured to source 24V AC.
When controlling more than one heater from one heat output, configure the output to source 24V AC to drive a relay(s) to keep the control loops separate.
Also, when controlling a line voltage heater, configure the heat output to source 24 V AC to drive a relay of sufficient capacity to run the heater.
The timer output sources 24V AC to drive a solenoid or relay(s). The solenoid should have a coil with less than a 24VA load.
The alarm is an open/closed contact. When the GHK12X2 is powered and operating properly the contacts are CLOSED. The contacts OPEN when power is lost or the high or low alarm is triggered.
The thermistor is the temperature sensor. The GHK12X2 has two thermistor inputs labeled TH1 and TH2. In single zone mode, the readings are averaged and displayed. In the 2-zone mode, heat 1 and cool 1 and cool 2 work to keep TH1 at the correct temperature. Also, heat 2 and cool 3 and cool 4 work together to keep TH2 at the desired temperature.The thermistors should be slightly above the plant height. To ensure proper readings, it should not be in direct sunlight or where it will be sprayed with water. It is generally placed closer to the cool air inlet and further from the heat. In the 1-zone mode separate the thermistors across the width of the greenhouse to give the best average temperature.
The thermistors come with 24' leads and can be connected directly to the two terminals for TH1 and to the two terminals for TH2. There is no special orientation to the thermistor leads.
Should you need to extend the leads of the thermistor, use the 3M Scotchlock TM sealed connectors provided. Use only wire size of 22-14 AWG to ensure proper connection. A faulty connection will cause erroneous temperature readings.
1 Turn off all breakers to the fans, heaters, etc.2 Turn on power to the GHK12X2
3 Use the "HEAT" and COOL buttons on the GHK12X2 to set all the outputs to "off" by pressing each button until the display reads "OFF" and then pressing enter. Press the "8" key (outputs). All segments should be off, indicating no outputs except HAF's should be on.
4 Check both temperatures by pressing the "5" key (Z1/Z2) to alternate between the two thermistor readings. Note the verticle display segment alternating between the Z1 and Z2 positions. Use the "5" key to display zone 1 temperature and apply heat to the thermistor 1 and make sure it repsonds. Use the "5" key to display zone 2 temperature and repeat the test.
5 Switch the breaker for all the appliances to "on". If HAF fans are connected they should be on and all other appliances should be off.
6 Use the "HEAT" and "COOL" buttons turn on each output and test each appliance. When testing the fans, make sure the louvres are open.
7 After you have confirmed all equipment is working, set all outputs to "auto" by pressing "menu" (rset will be displayed) then "enter".
8 Refer to the operating manual for instructions on programming.