Carrier 38BYG Product Data

Also see for 38BYG Series: Wiring diagrams Installation and start-up instructions Installation and start-up instructions

Contents

6Accessory description and usage (continued)8. Filter DrierA device for removing contaminants from refrigerant circulating in a heat pump system: two-direction flow.Usage Guideline:Suggested in all field-connected split-system heat pumps.9. High-Pressure SwitchAuto reset SPST switch activated by refrigerant pressure on high side of refrigerant circuit. Cycles compressor off if refrigerant pressure rises to 426 ± 10 psigand resets at 320 ± 20 psig. Provides protection against compressor damage due to loss of outdoor airflow.Usage Guideline:Suggested in installations exposed to "very dirty" outdoor air.Suggested in installations where condenser inlet air temperature exceeds 125°F (51.7°C).10. Isolation RelayAn SPDT relay which switches the low-ambient controller out of the outdoor fan motor circuit when the heat pump switches to heating mode.Usage Guideline:Required in all heat pumps where low-ambient kit has been added.11. Liquid-Line Solenoid Valve (LLS)An electrically operated shutoff valve which stops and starts refrigerant liquid flow in response to compressor operation. It maintains a column of refrigerantliquid ready for action at next compressor operation cycle. It also provides system protection against off-cycle refrigerant migration.Note: When LLS is used with reciprocating compressors, Compressor Start Assist — Capacitor and Relay is required.Usage Guideline:Required in all heat pump long line applications to control refrigerant off cycle migration in the heating mode. A second LLS or hard shut offTXV is required in heat pump long line applications for refrigerant off cycle migration in the cooling mode. See Long Line Application Guide-line.12. Low-Ambient Pressure SwitchA long life pressure switch which is mounted to outdoor unit service valve. It is designed to cycle the outdoor fan motor in order to maintain head pressurewithin normal operating limits (approximately 100 psig to 225 psig). The control will maintain working head pressure at low-ambient temperatures down to 0°F(–17.8°C) when properly installed.Usage Guideline:A Low-Ambient Pressure Switch or MotorMaster ®—Low-Ambient Controller must be used when cooling operation is used at outdoor tem-peratures below 55°F (12.8°C).13. MotorMaster®—Low-Ambient ControllerA fan speed control device activated by a temperature sensor. Designed to control condenser fan motor speed in response to the saturated, condensing temper-ature during operation in cooling mode only. For outdoor temperatures down to –20°F (–28.9°C), it maintains condensing temperature at 100°F ± 10°F (37.8°C± –12°C).Usage Guideline:A MotorMaster ®—Low-Ambient Controller or Low-Ambient Pressure Switch must be used when cooling operation is used at outdoor tem-peratures below 55°F (12.8°C).Suggested for all commercial applications.14. Outdoor Air Temperature SensorDesigned for use with Carrier Thermostats listed in this publication. This device enables the thermostat to display the outdoor temperature. This device also isrequired to enable special thermostat features such as auxiliary heat lock out.Usage Guideline:Suggested for all Carrier thermostats listed in this publication.15. Outdoor ThermostatAn SPDT temperature-actuated switch which turns on supplemental electric heaters when outdoor air temperature drops below a user-selected set point.Usage Guideline:Electric supplemental heat applications in non-variable speed indoor units when electric heat staging is desired.16. Secondary Outdoor ThermostatAn SPDT temperature-actuated switch which turns on third-stage of supplemental electric heaters when outdoor air temperature drops below the second-stageset point.Usage Guideline:Outdoor Thermostat applications where electric heater is capable of 3-stage operation.17. Sound HoodWraparound sound reducing cover for the compressor. Reduces the sound level by about 2 dBA.Usage Guideline:Suggested when unit is installed closer than 15 ft to quiet areas—bedrooms, etc.Suggested when unit is installed between two houses less than 10 ft apart.18. Thermostatic Expansion Valve (TXV) Bi-FlowA modulating flow-control valve which meters refrigerant liquid flow rate into the evaporator in response to the superheat of the refrigerant gas leaving theevaporator. Kit includes valve, adapter tubes, and external equalizer tube. Both hard shutoff and RPB valves are available.Note: When using a hard shut off TXV with single phase reciprocating compressors, a Compressor Start Assist — Capacitor and Relay is requiredUsage Guideline:Required to achieve ARI ratings in certain equipment combinations. Refer to combination ratings.Required for use on all zoning systems.See long line guideline.19. Time-Delay RelayAn SPST delay relay which briefly continues operation of indoor blower motor to provide additional cooling after the compressor cycles off.Note: Most indoor unit controls include this feature. For those that do not, use the guideline below.Usage Guideline:For improved efficiency ratings for certain combinations of indoor and outdoor units. Refer to ARI Unitary Directory.