I just moved into an old home, that has only 2 connected smoke detectors outside of the pure wireless ones. They are quite old, so I got 2 Halo+ to connect them. I noticed that the old ones, BRK 2812th models, are 4 wires (I think maybe into an alarm panel I dont use). Assuming I replace both, there should be no issues going to a 3 wire Halo? ANyone have experience between 3 and 4 wire smoke detectors.
The only issue I’m aware of is if your wiring is not 120VAC.
Some smoke alarms that connect to a panel are 12VDC and this does not work with the Halo.
Hope this helps.