A2L Refrigerants and Arzel Zoning
There’s been a big change in HVAC this year with the introduction of A2L refrigerants. By now, most of our customers have done some kind of training on R-32 or R-454B refrigerant. The new class of refrigerants does have some impacts on zoning. Here’s what you need to know about HVAC zoning with A2L refrigerants.
A2L Refrigerant Mitigation Controls
Indoor coils that are designed for A2L refrigerants have mitigation controls that respond if they detect a refrigerant leak. These are important because A2L refrigerants are mildly flammable. If there is a leak, the system needs to respond by dispersing the refrigerant.
How Does A2L Affect Zoning Systems?
According to UL, when an A2L refrigerant leak is detected, all zoning dampers need to be opened. When you’re installing A2L equipment with an Arzel Zoning system, you’ll need to add a relay to accomplish this functionality.
How To Implement A2L Mitigation Wiring on an Arzel Zoning System
To add the necessary functionality to an Arzel Zoning system, follow the wiring diagram below. You will wire a double-pole double-throw relay to the mitigation board and the Arzel Zoning panel. This will shut off the panel and open all dampers in the event of a refrigerant leak.

Download A2L Mitigation Wiring Diagram
What Happens When I Implement A2L Mitigation Wiring?
Okay, so you added the relay for A2L mitigation. Now what? Here’s what will happen if the A2L control detects a leak:
- The A2L control closes NO contacts
- The Arzel Zoning board will lose power
- The Arzel air pump will run continuously
- All zoning dampers will open
Does Arzel Have a Circuit Board with A2L Mitigation Built In?
We are working on adding a circuit to our new products that will directly connect to the mitigation board in the equipment without the need for a relay. Right now, you’ll need to use the wiring diagram above to add that functionality.