Relay Logic Circuit for a 24 VAC output in Heat Pump Defrost Mode (Symbio 700)
Overview:
This circuit will provide a 24 VAC output from a Symbio 700 Heat Pump Condenser in Defrost Mode.
You will need to purchase 2 Relays, one must have Normally Closed contacts, and the other must-have Normally Open contacts.
Light Commercial Tech Support will not be responsible for providing part numbers for the relays.
Theory of Operation
If the Symbio 700 is calling for a compressor to run, and not calling for a condenser fan to run, the unit is in Defrost Mode...so output 24 VAC.
Referring to the diagram above:
Unit Idle
R1 = Coil Not Energized, Contacts Closed
R2= Coil Not Energized, Contacts Open
OFC1 coil, R1 coil, and CC1 coil are not energized, no 24VAC is present to energize Relay R2 coil, and 24 VAC from AB J15-1 cannot pass through R2 contacts.
Cool or Compressor Heat Mode
R1 = Coil Energized, Contacts Open
R2= Coil Not Energized, Contacts Open
OFC1 and R1 coils energized (opening R1 Contacts) not allowing 24 VAC energizing CC1 coil to energize R2 coil. 24 VAC from AB J15-1 cannot pass through R2 contacts.
Defrost Mode
R1 = Coil Not Energized, Contacts Closed
R2= Coil Energized, Contacts Closed
24 VAC energizing CC1 coil passes through R1 Normally Closed contacts to energize R2 Coil (closing R2 contacts), 24 VAC from AB J15-1 passes through R2 contacts.
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.