ReliaTel Condenser Fan Control Logic - E-flex Unit
For units that have two condenser fans, the special control logic is designed to provide proper condenser head pressure control at different ambient conditions. With the normal operation, either one or both fans will be operating depending on the outdoor temperature.
Control logic resides in the RTRM module. When the outdoor ambient drops below 60 degrees the second condenser fan will be turned off. When the outdoor temperature reaches 65°, the fan will once again restart.
When only one condenser fan is running, the second fan will “windmill” backward. This is caused by air
being drawn in through the opening of the fan orifice which bypasses the condenser coil. If the windmilling is fast enough and the condenser fan is energized, it can actually start and run in the reverse direction. To prevent this, when there is a call for the second condenser fan to start, control logic forces the first condenser fan to shut off for seven seconds to allow the second fan to slow down. After seven seconds, both the first and the second condenser fan will restart. Because the contractors that provide power to the condenser fan are also the same ones used to power the compressors, both compressors (if the second compressor is running) will also shut down during the seven-second interval. When the fans restart, the compressor will also restart.
E-Flex Units
The same signal from the VSM that controls the compressor speed also controls the speed of the condenser fans. The condenser fan speed is determined by the variable speed compressor speed
and the outdoor air temperature.
Look at table 29 condenser fan control data 12.5 - 17.5 tons on the ReliaTel manual - Click the link below
*Please refer to the latest available literature when available.*
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.