- *LCU How do I set up Demand Control Ventilation for units with RTEM, RTRM>v8.0, and CV only?
How to properly setup Demand Control Ventilation (DCV) with the RTEM and RTRM versions greater than 8.0. Constant volume units only.
Process:
The RTEM module replaces the Honeywell Economizer Control Actuator (ECA) module and will operate with RTRM versions 8.0 and above as described below.
All Of the conditions below must be met for Demand Control Ventilation (DCV) to operate:
- Power is applied to the RTRM and RTEM
- Unit mode is occupied
- Space CO2 value is valid (approximately 2 to 10 volts DC)
The "DCV" and the "DESIGN" potentiometers set the economizer damper travel limits for minimum damper position and DCV operation. These settings have no effect on economizer cooling operation.
The following information only applies if there is a valid signal (approximately 2 to 10 volts DC) on the DCV terminal of the RTEM.
The "DCV" potentiometer is the minimum position the outdoor air damper will drive to whenever the fan is turned on and the unit is in the occupied mode.
The "DESIGN" potentiometer is the maximum position the outdoor air damper will drive to while in the active Demand Control Ventilation mode (CO2).
The "LL" (Lower Limit) potentiometer adjusts the CO2 level set point, in Parts Per Million (PPM), at which the fan will turn on and the damper will travel to the "DCV" potentiometer set point to ventilate the space. The RTEM will monitor CO2 PPM and modulate the damper between the "DCV" and "DESIGN" damper set points until the CO2 level drops below the "LL" (Lower Limit) value. If the CO2 level rises above the "UL" (Upper Limit) set point the damper will be driven to the "DESIGN" potentiometer set point until CO2 levels drop below the "UL" set point.
Notes:
If a valid DCV signal is NOT present the "DESIGN" potentiometer set point will determine the minimum position of the economizer damper when the indoor fan is running.
If a valid CO2 set point IS present the "DCV" potentiometer set point determines the minimum position of the economizer damper.
WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.