Quarter 1, 2025
Refrigerant detection systems play a crucial role in ensuring the safety and efficiency of HVAC systems by monitoring refrigerant levels and identifying potential leaks. These systems are designed to protect both the equipment and the occupants of a home by automatically responding to any detected refrigerant leaks, preventing further damage and maintaining proper system functionality. In this FAQ article, we’ll address common questions about refrigerant detection systems, their features, installation requirements, and how they interact with various HVAC components, helping homeowners and technicians better understand their operation and maintenance.
Many of our products use safety circuits that can either reset the system or shut down the system. The homeowner knows to call their dealer when their system is not meeting temperature set-point, or it’s off altogether. The refrigerant sensor and control is another safety circuit. To ensure all system configurations are properly controlled in the event of a leak, the 24 VAC power to the thermostat is disconnected while the indoor unit purges any refrigerant concentration from the plenum. During this time, if the thermostat is not battery-powered, then the thermostat screen will go blank, but come back on after purging is complete. While the leak is being purged, the homeowner will not have heating or cooling available. Over time, if enough refrigerant has leaked out of the system and has been purged, the system will shut down on a low-pressure condition.
• The system will reset after the purge sequence is complete and there is no lockout mechanism on the RDSC.
• After refrigerant concentration is sensed below the limit the system will resume normal operation.
While there is no UL requirement for an audible alarm, the RDS control comes with a dry contact to wire to an external alarming system. If the system is equipped with an audible alarm, then the audible alarm will sound upon a leak detection
If the sensing device fails, the RDSC will force the indoor unit blower to be on at all times. The homeowner will notice that their blower is running continuously at high speed and should contact their dealer to troubleshoot at this time. The system will resume normal operation after the sensor itself has been replaced.
In applications where gas furnaces do not have controls that support the refrigerant sensing device, a field installed kit is used to ensure the sensor can communicate to the furnace.
There are two kits available: a 24V RDSC field kit and a Communicating RDSC field kit. The 24V RDSC kit should only be used with systems that use standard 24V control and not digital communication. The communicating RDSC kit should be used with any communicating-enabled system that features digitally communicating equipment (either solely communicating or in combination with 24V equipment).
Field kit installation will take approximately 30 minutes to add to the system. The kit intercepts the wiring between the indoor unit, outdoor unit, and thermostat. The installation guide includes wiring diagrams for typical system configurations and combinations (Single-Stage, Multi-stage, AC / Gas Furnace, Heat Pump / Gas Furnace, Fully Communicating, Hybrid 24V-Communicating, ERV/HRV, and others).
The system will still operate. However, clear product warnings are displayed on all compatible Allied coils indicating that an RDS is required with this coil.
Yes, a filed installed kit is available for Multi-Refrigerant Air Handlers. Multi-refrigerant air handlers ship ready for R-410A applications and can be field converted to R-454B by changing the TXV and adding both a controls kit and a sensor kit.
No, but a refrigerant sensor will need to be connected to the furnace if the outdoor unit uses R-454B refrigerant. A field installed kit (RDSC) is required to connect the sensor to the furnace if the furnace does not have the integrated furnace control board from the factory. Note that models with the factory installed integrated furnace control board will have a “K” in the nomenclature.
No, as they are outdoor units not in a confined space.
Mini-Split systems will have a sensor for refrigerant leak detection and all outdoor multi-zone models will have a valve control.
All Residential Package Units will have a factory installed sensor for refrigerant leak detection – these R-454B units will be identified with a “7” in the nomenclature.
The 24V RDSC kit is compatible with thermostats that are either battery powered or feature non-volatile memory. Non-digital thermostats are also compatible. To check if a homeowner’s thermostat is compatible, refer to the installation guide.
Yes, but it is the responsibility of the coil manufacturer to supply the refrigerant sensing device and the controls to integrate with the furnace.
You can identify Low GWP equipment through the model nomenclature – furnaces have a “K” while outdoor units containing R-454B refrigerant have a “7”.
Not for residential applications.