Hvac / Heat Pumps
Carrier Infinity 18VS Variable Speed Heat Pump Wiring Guide
Quick reference guide for the Carrier Infinity 18VS heat pump wiring, including unit operation, defrost settings, and installation requirements.
Table of contents
Quick guide from the manual
This document provides the official wiring diagram and operational parameters for the Carrier Infinity 18VS Variable Speed Heat Pump. It is intended for qualified technicians to ensure proper installation and system configuration.
Unit operation
The system includes a 3.5-minute short cycle protection and a 3.5-minute delay after compressor off cycles. To bypass the delay, a forced short defrost can be initiated for 1 second.
Defrost settings
- Defrost Time Selection: The defrost interval can be set to 30, 60, or 120 minutes via the User Interface or DIP switches. If the outdoor temperature is less than 37°F, the default interval is 60 minutes.
- Defrost Initiation: Defrost will only occur when outdoor temperatures are below 50°F. It initiates when the selected time has elapsed and the coil temperature is 32°F or lower. It terminates at 65°F, 50°F, or 45°F (+/- 5°F), or when the outdoor fan turns on after 15 seconds.
- Forced Defrost: To initiate a forced defrost, place a jumper across the forced defrost terminals for 5 seconds. The unit will terminate the cycle when the coil temperature reaches 65°F or after 30 seconds of active mode.
Installation requirements
- All wiring must comply with the National Electric Code (N.E.C.) and local codes.
- Use copper conductors rated for at least 75°C (167°F).
- Two wires are required for communication.
- Do not attempt to operate the unit until service valves have been opened.
- If communicating thermostats are used, they must be compatible with the Infinity or Evolution user interface.
- For non-communicating thermostats, 24VAC must be provided to the R connection.
- N.E.C. Class 2, 24V circuit, minimum 40VA required, 60VA on units installed with LLS.
Manufacturer information
Carrier Global Corporation
Practical help
Common problems
Unit will not initiate defrost
Ensure outdoor temperature is below 50°F and coil temperature is 32°F or lower.
Communication error with thermostat
Verify that the thermostat is a compatible Infinity or Evolution series interface.
Before use
- Ensure all electrical connections inside the control box are tight.
- Verify that service valves have been opened before attempting operation.
- Confirm the use of copper conductors rated for at least 75°C.
- Check that the 24V circuit meets the minimum 40VA requirement (60VA with LLS).
Specs in practice
- Defrost Interval
- The time frequency at which the system checks for ice buildup (30, 60, or 120 minutes).
- Short Cycle Protection
- A 3.5-minute delay designed to protect the compressor from rapid cycling.
Model compatibility
- Requires Infinity or Evolution series communicating thermostats.
- Non-communicating thermostats require a 24VAC supply to the R terminal.
Manual page author
Emily Carter
User documentation editor
Prepares concise manual descriptions and highlights the most useful setup, operation, and maintenance information for readers.