No, they are not connected for alarm sounds and you can not externally trigger the alarms as well.
But since you have Homey, you can play alarm sounds on your smart speakers (and have them say where smoke is detected), add external sirenes, turn on (or flash) your lights, open the curtains, blinds, close gas main, etc, etc…
I recommend frient or develco smoke detector. They work very well and integration is easy.
For these devices: when a smoke alarm is triggered, do they all sound the alarm?
Or is homey able to trigger the alarm?
Dont want to add yet another device (seperate sounder) to the wall. Especially not when the smoke alarm has a sounder.
I only found the popp to support this. (But did not see friend or develco yet)
To be honest it’s very disapointing you cannot trigger them all…
