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2024 Lennox Industries Inc.
©
Dallas, Texas, USA
This manual must be left with the
owner for future reference.
Certifications ............................................................ 3
Shipping and Packing List ....................................... 3
Overview.................................................................. 3
Operating Environment Specifications .................... 3
Product Features ..................................................... 4
Introduction .............................................................. 5
Dimensions .............................................................. 6
Installation ............................................................... 7
Sensor Part Number Verification ......................................... 7
Mounting Methods ............................................................... 7
Mounting Location ............................................................... 7
Condensate Safety Switch (Float Switch) ........................... 8
Routing the Sensor Cable.................................................... 9
Making the Connection ...................................................... 10
Secondary Sensor ..................................................11
Additional Line Set Joints ..................................................11
Multiple Systems Installed in Same Space .......................11
DIP Switch Settings ............................................... 12
Modes of Operation ............................................... 12
Initializing .......................................................................... 12
Normal ............................................................................... 12
INSTALLATION AND
Potential (GWP) Refrigerant
Detection System (RDS)
Non-Communicating Control
CONTROLS
508426-01
Contents
Refrigerant Detected..........................................................12
Fault ...................................................................................13
Diagnostic Codes .................................................. 13
Red LED Diagnostic Codes ...............................................13
Test Button Functionality ....................................... 14
Test Button - Additional Functions .....................................15
Thermostat Compatibility ....................................... 15
Compatibility Verification ...................................................16
Additional Applications........................................... 16
Zone HVAC System ...........................................................16
External Alarm ...................................................................16
Start Up Test Procedure ........................................ 17
Cooling Demand ................................................................17
Heating Demand ...............................................................17
Wiring Diagrams .................................................... 18
Single Stage Heat Pump with Air Handler .........................19
Handler .............................................................................20
Diagnostic Codes and Troubleshooting ................. 26
SETUP GUIDE
Low Global Warming
Board (
24 Volt Only)
Supersedes 4/2024
10/2024
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Summary of Contents for Lennox RDS
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Page 1: Table Of Contents
INSTALLATION AND SETUP GUIDE 2024 Lennox Industries Inc. © Low Global Warming Dallas, Texas, USA Potential (GWP) Refrigerant Detection System (RDS) Non-Communicating Control Board ( This manual must be left with the 24 Volt Only) owner for future reference. CONTROLS... - Page 2 WARNING WARNING Improper installation of the RDS Non- Improper installation, adjustment, Communicating Control Board may lead to alteration, ser vice or maintenance can unreliable equipment operation and unreliable cause property damage, personal injury or refrigerant detection. loss of life. In addition to installing the RDS...
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Page 3: Certifications
(40°C) NOTE: This kit is sold separately from the refrigerant detection sensor. The refrigerant sensor is included as part of a Lennox sensor kit, R-454B-only coil, or R-454B-only air handler. Overview Lennox Low GWP Refrigerant Detection ®... -
Page 4: Product Features
• Multicolor LED (light-emitting diode) communicates the state of the RDS Non-Communicating Control Board • Test/Reset button (to verify the functionality of the RDS Non-Communicating Control Board) • Composite case with mounting hardware for drywall installation • Supports a maximum of two refrigerant detection sensors •... -
Page 5: Introduction
Low GWP Refrigerant Detection System (RDS) ensures safe operation of Lennox ® residential HVAC systems equipped with R-454B refrigerant. The RDS activates the blower if refrigerant levels within the cabinet reach 12% of the lower flammability limit (LFL). NOTE: The UL standard is 25% of the LFL. -
Page 6: Dimensions
(171.5 mm) 3-5/8 in. 6-3/4 in. 7-7/16 in. (92.1 mm) (171.5 mm) (189 mm) 2-1/2 in. (127 mm) 3-5/8 in. (92.1 mm) 1-3/8 in. (34.9 mm) Bo om View 1-1/8 in. (28.6 mm) Figure 2. RDS Non-Communicating Control Board - Dimensions... -
Page 7: Installation
For attic/crawl- (sold separately) space/basement installations, use the includ- ed and field-provided hardware. The RDS sensor must be mounted as spec- ified in its accompanying manual. Mounting Mounting Location the sensor incorrectly or in an improper loca- The RDS Non-Communicating Control Board tion may result in refrigerant detection failure. -
Page 8: Condensate Safety Switch (Float Switch)
Control Board wiring diagrams. This ensures the RDS Non-Communicating Control Board is powered continuously and operates normally. Do not wire the condensate safety switch or any other field installed safety switches between the indoor unit transformer and the RDS Non-Communicating Control Board. The RDS Non-Communicating Control Board must remain powered at all times. -
Page 9: Routing The Sensor Cable
Routing the Sensor Cable Figure 3 illustrates how to best route the sensor cable from the RDS Non-Communicating Control Board to the sensor within the indoor unit for the Upflow, Downflow, and Horizontal orientations. For details on mounting the sensor itself, refer to the respective sensor kit, air handler, or coil installation guide. -
Page 10: Making The Connection
Molex connection point for a secured connection, as shown below in Figure 4. Verify the connection is free of dust, debris, and moisture. Molex Plug Clip Figure 4. Connecting the RDS sensor to RDS Non-Communicating Control Board... -
Page 11: Secondary Sensor
Connect the refrigerant sensor to the second sensor input on the RDS Control. Refer to the in- structions provided with the RDS sensor or the RDS controller to enable the second sensor (see... -
Page 12: Dip Switch Settings
DIP Switch Settings Modes of Operation Adjust the DIP switch settings to the sensor The modes of operation for the RDS Non-Com- configuration. Failure to do so will cause faults municating Control Board are Initializing, Nor- on power-up. mal, Refrigerant Detected, and Fault. -
Page 13: Fault
HVAC system to shut down on steps. a low refrigerant pressure limit 1. A rapid flash indicates the RDS Non-Communicating condition. Control Board is in the process of sensor enumera- tion Fault 2. A blue flash indicates a purge has previously oc- curred. -
Page 14: Test Button Functionality
Test Button Functionality Table 3. Red LED Diagnostic Codes Applies to Issue Action The RDS Non-Communicating Control Board Flash Individual Sensor(s) is equipped with a Test/Reset button. The Test button can be used to complete several func- Spare Code -... -
Page 15: Test Button - Additional Functions
Button while the RDS Non-Communicating Thermostats that preserve memory settings Control Board is functioning within the states are compatible with the RDS Non-Communi- of Initializing, Monitoring, Refrigerant Detec- cating Control Board. Examples include: tion, Servicing and Fault. Refer to “Table 2. -
Page 16: Compatibility Verification
Wait five (5) minutes before supplying power to the furnace If the RDS Non-Communicating Control Board is installed in a zone HVAC system, the RDS breaker. Non-Communicating Control Board will open Note whether the thermostat maintained all zone dampers if refrigerant is detected. -
Page 17: Start Up Test Procedure
Prompt a heating demand at the thermostat. The RDS Non-Communicating Control Board is equipped with a Test/Reset button, see “Test Press the Test button on the RDS Non- Button Functionality” on page 14. After the Communicating Control Board. RDS Non-Communicating Control Board has... -
Page 18: Wiring Diagrams
Wiring Diagrams Lennox provides wires designated for wiring the sensor cable. Wires required for the RDS instal- lation are field supplied. The RDS supports OEM and non-OEM split gas furnace and air handler installations. Wiring diagrams are provided for several common split furnace system configurations to identify exact wire types and terminal locations. -
Page 19: Single Stage Heat Pump With Air Handler
Single Stage Heat Pump with Air Handler RDS Sensor Thermostat Air Handler SENSOR #1 SENSOR #2 RDS Field Kit – 24 Volt Cat # (27A02) OPTIONAL TSTAT INDOOR N.C. CONDENSATE ZONING ALARM FLOAT SWITCH NO COM NC NO COM NC... -
Page 20: Single Stage Outdoor Unit With Single Stage Furnace/Air Handler
OPTIONAL N.C. CONDENSATE RDS Sensor FLOAT SWITCH Indoor Unit Thermostat SENSOR #1 SENSOR #2 RDS Field Kit – 24 Volt Cat # (27A02) Single Stage Furnace / TSTAT INDOOR Single Stage Air Handler ZONING ALARM NO COM NC NO COM NC... - Page 21 OPTIONAL N.C. CONDENSATE FLOAT SWITCH Single Stage Gas Furnace/AHU Thermostat SENSOR #1 SENSOR #2 RDS Field Kit – 24 Volt Cat # (27A05) TSTAT INDOOR ZONING ALARM NO COM NC NO COM NC Thermostat / Outdoor Unit Terminal Block (BLACK)
- Page 22 OPTIONAL N.C. CONDENSATE FLOAT SWITCH Two Stage Gas Furnace/AHU Thermostat SENSOR #1 SENSOR #2 RDS Field Kit – 24 Volt Cat # (27A05) TSTAT INDOOR ZONING ALARM NO COM NC NO COM NC Thermostat / Outdoor Unit Terminal Block (BLACK)
- Page 23 NO COM NC NO COM NC 240 V 208 V Black 120 V 24 Volt Transformer C# 67K65 Yellow Outdoor Unit Thermostat / Outdoor Unit Terminal Block (BLACK) Indoor Unit Terminal Block (BLUE) For Non -Lennox Dampers: The relay must be wired as “Powered Open.”...
- Page 24 Variable Speed NO COM NC NO COM NC Indoor Unit Black Yellow Blue Two Stage Outdoor Unit Thermostat / Outdoor Unit Terminal Block (BLACK) Indoor Unit Terminal Block (BLUE) For Non -Lennox Dampers: The relay must be wired as “Powered Open.”...
- Page 25 24 Volt Transformer 240 V 208 V OPTIONAL Thermostat N.C. CONDENSATE 120 V C Y G FLOAT SWITCH RDS Sensor C Y G C Y G C Y G C Y G Thermostat 4 Thermostat 3 Thermostat 2 PS BP Sensor...
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Page 26: Diagnostic Codes And Troubleshooting
Diagnostic Codes and Troubleshooting Table 6. LED Diagnostic Codes State LED Diagnostic Code Action Required Initializing Flashing green None Solid green. If a prior mitigation occurred, a Monitoring None blue flash interrupts the solid green LED. Mitigating Check coil tubes for refrigerant. Repair the issue (Refrigerant Flashing blue and restart the equipment.
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