BCI-R / BCI2-R Dehumidification w/ Comparitive Enthalpy Economizer Control
Summary:
BCI-R / BCI2-R Dehumidification with Comparitive Enthalpy Economizer Control is a system that combines two types of control strategies in HVAV systems
The Light Commercial Unit (LCU) must be capable of dehumidification. Under normal operating conditions for the LCU to go into Dehumidification mode, the Cooling Capacity must be less than 50% and Space Humidity active must be greater than the Dehumidification Setpoint active.
- BCI-R / BCI2-R LCU with Comparitive Enthalpy Economizer strategy.
BCI-R / BCI2-R LCU’s with Comparitive Enthalpy Economizer control strategy that is being integrated into any BAS application, the RAH sensor value that is being used for the Economizer Comparitive Enthalpy control strategy, will report as Analog Input 16, Space Humidity Active by default. This RAH sensor value will not be used for dehumidification control, due to already being utilized for the Economizer Control strategy. For Dehumidification control, the RTU will require either a hardwired humidity sensor connected to LTB3, 18(RH+) and 19(RH-) or BAS will need to write to AO-25, Space Humidity BAS. To verify if the RAH humidity sensor is reporting as AI-16, it is recommended to disconnect the RAH sensor for the RTEM and verify if the value reports 255% (null value) or a value from the hardwired humidity sensor connected to LTB3, 18-19 (polarity sensitive) or the value BAS is writing to AO-25, Space Humidity BAS.
- BCI-R / BCI2-R Air-Fi WCS Humidity sensor
The RTU must be capable of dehumidification to have the points required for use with the AirFi humidity sensor.
If AO-25, Space Humidity BAS is created, AO-21, space dehumidification setpoint BAS will be created.
See below for when AO25 is created. The BCI-R must be in BAS control to use the Wireless Humidity or Wireless Temperature and Setpoint values. Space Humidity Active will report the AirFi sensor value, so long as the BAS system isn’t providing an overriding value. The Air-fi Humidity sensor is used for dehumidification.
This only applies to units with dehumidification enabled. If there is no analog output 25, Space Humidity BAS, the unit will not read a humidity value from the AirFi humidity module.
If a BAS system is writing to AO-25, its value will be transmitted to Reliatel for control.
If a BAS system is not writing to AO-25, or the value from the BAS system is in a Fault condition, and a Wireless Humidity value is detected, its value will be transmitted to Reliatel for control.
If no BAS or Wireless Humidity value is detected, no Humidity Value will be transmitted to the Reliatel controller.
Except LCU’s with Comparitive Enthalpy Economizer control strategy. The RAH sensor value that is being used for the Economizer Comparitive Enthalpy control strategy, will be referenced as Space Humidity Active by default.
If no BAS or Wireless Humidity value is detected, no Humidity Value will be transmitted to the Reliatel controller.
Except LCU’s with Comparitive Enthalpy Economizer control strategy. The RAH sensor value that is being used for the Economizer Comparitive Enthalpy control strategy, will be referenced as Space Humidity Active by default.
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.