adding a dome siren to my smartthings hub v3. I have 2 first alert smoke detectors and 4 fibaro water sensors connected to the hub. Will adding the siren allow me to receive an audible alarm from the siren when water or smoke is detected?
Sure. The siren may look like a “switch” in the rule creator, but you can set up an automation to turn it on when the sensor triggers. The exact way you do that varies a bit depending on which version of the app you are using, but you should be able to do it. Depending on the exact details, you might use the smart lighting app (again, because the siren acts like a switch), a smart home monitor custom alert, Or the custom automation creator (in the new app). But there should be an official feature that lets you create a rule for what you describe. 