Issue:
Condenser fan staging
Resolution:
The RTUA controls are unable to control the fan staging for a non-RTCA Condenser. Signals to start the fan sequence are available off of 1TB4, 3 (for circuit 2) and 1TB4, 7 (for circuit 1) with the ground on 1TB4, 11. The signals are energized when the respective compressor starts. Staging of the fans of a non-RTCA condenser is the responsibility of the customer.
- Because of normal fan staging, ALL fan contacts will cycle ON/OFF
- You will need to Enable FAN Control and Enable VARIABLE SPEED FAN Circuit 1/Circuit 2
- You will need to supply jumpers on the VFD Fault Input of each of the compressor modules (1U4 and 1U5) between 1TB9-7,8 and 1TB9-3,4.
- If you do not provide the jumpers and enable VFD operation, the chiller will trip out on diagnostics such as: HPC, Overload, etc.,...
Notes:
If a non-RTCA Condenser is supplied, it must be capable of providing a minimum of 5F subcooling at the EXV. The RTUA requires subcooled liquid at the EXV's. Without a minimum of 5F subcooling, the RTUA will not operate as designed.
Changes:
Other Question/Problem/Cause Statements:
- Condenser fan staging.
Facts:
- RTUA
- non-RTCA Condenser
- Compressor Chiller (Pueblo) (RTUA)
Original HUB Document : DOC-81808
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.