BCI-R Unit does not respond to rise in CO2 level. BCI-R. How does Demand Control Ventilation work on the BCI-R?
Summary:
There can be several reasons why the BCI-R unit may not respond to a rise in CO2 levels. Here are a few troubleshooting steps you can try
- In order to allow the local Economizer (RTEM) to perform Demand Control Ventilation based on CO2 levels we must release control of the minimum position.
- This is done by setting BCI-R Binary Output 7, Economizer Minimum Position Enable Command to "Disable" (Inactive). B0 7 must be "In Service".
- Analog Output 1, Economizer Minimum Position Setpoint BAS will not work, and should be placed out of service.
- DCV will work with this setting but, if any adjustments need to be made to the DCV operation they can only be made by turning the CO2 and position setpoint dials on the Economizer Module (RTEM).
- DCV will work with either a valid CO2 value, from a local sensor terminated at the RTEM DCV input or with a value communicated to Analog Output 18, Space CO2 Concentration BAS.
- AO-18, Space CO2 Concentration BAS must be updated every 15 minutes or less to remain valid. If the communicated value is valid, the point is in service, and the unit is in BAS control, the communicated value will take priority over the local value at the Economizer Module (RTEM) DCV input.
NOTE: If you want to retain BAS control of the Minimum position the BAS system must make the DCV calculations/decisions at the front end system controller. The control for DCV is "All or Nothing"- we must totally release control or totally take over control.
LCI-R and LCI-RX
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The same principle as described above applies to LCI-R and LCI-RX.
- In this case the minimum position SNVT, (nviOAMinPos) must be set to "Not Used" and left at the default value of 7FFF to allow the local DCV scheme to operate. Otherwise the BAS must take over the DCV function entirely.
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.