Environmental Controllers


Controller Overview


Up to 6 vents can be controlled in one zone; two ridge vents, two side vents and two end vents.

Vents can be controlled by any combination of the following :-

  • Inside air temperature
  • Outside air temperature
  • Wind speed and direction
  • Raining
  • Humidity
  • Inside humidity.


  • Heron environmental controllers operate either separate thermal and shading screens or one combined screen.
  • Thermal screens can be controlled by time, light, and inside and outside air temperature.
  • Thermal screens have a delayed opening feature to allow gradual air circulation.
  • Shading screens can be controlled by time or light.
  • Two gap positions can be specified for high inside temperatures.

Hot Water Heating

  • Heron controllers operate a hot water motorised valve and a local circulating pump.
  • Hot water heating controls air temperature or minimum and maximum pipe temperature.
  • Hot water heating can be immediately shut off if a specified high vent position is reached.
  • Glasshouse humidity can be reduced by maintaining a minimum pipe temperature.

On-Off Heating

  • Heron environmental controllers operate two heaters; a main and a back up heater.
  • Heating can be initiated by a low inside air temperature threshold or by a falling temperature gradient.
  • Heating can be disabled with a specified high vent position.
  • The Back-up heater can be set to start at a lower temperature threshold.


  • Heron environmental controllers can operate two cooling fans and one circulating fan.
  • Circulating fans can be controlled by time or humidity.
  • Circulating fans can be disabled with high vent position.
  • The first cooling fan is started when a high inside air temperature threshold is reached.
  • The second cooling fan can be started if a higher inside temperature threshold is reached.


  • Up to four control periods can be specified to allow for different settings throughout the day.
  • Time periods can be set using “time of day” or astronomic time.

Full Range of Sensors

Heron environmental controllers can be integrated with our full range of sensors.

  • Outside air temperature
  • Aspirated inside temperature
  • Pipe temperature
  • Wind Speed
  • Wind Direction
  • Raining
  • Light
  • Humidity

Hardware Specification


  • All outputs are general purpose.
  • Outputs are configured at installation to perform the required control function, e.g. heater output, vent output.
  • Vents, screens and motorised valves require two outputs, open and close.
  • One alarm output is available for each zone. The alarm output is activated on high temperature, low temperature, sensor fault, zone fault.
  • All outputs are 24V AC (to operate 24V AC relays).
  • The total output current is 1.0 Amp per module.
  • All outputs are protected with electronic overload cut-out.
  • Output current is measured for diagnostic display purposes.
  • All outputs are protected against electrical surges exceeding ANSI C62surge suppression standards.
  • Designed to operate in an industrial environment. High electrical noise immunity, can withstand a 2.5KV spike.

Inputs - Base Module

  • Digital input for inside temperature and/or humidity.
  • Digital input for pipe temperature or boiler alarm.
  • Digital input for Heron Weather Station.
  • One data connector to connect PC and GSM mobile phone module.

Inputs - Remote Zone Module

  • Digital input for inside temperature and/or humidity.
  • Digital input for pipe temperature or boiler alarm.


  • All sensors connect via “Heron digital link”.
  • Digital link does not require special cable. Use standard 4 core cable.
  • Sensors can be connected up to 200m from the base module.
  • Inside temperature sensor range 0 - 50
  • Wind speed 0 - 70mph (+/- 5mph).
  • Light sensor range 0 - 2000W/m