The Roost Smart Battery is such an ingenious invention: The $35 battery replaces the 9-volt in your smoke alarm, pairs with an app, and lets you silence false alarms from your phone and sends you alerts when there’s actually a problem. The new RSA-400 is a four-in-one smoke alarm from Roost that works with the battery as its backup, but it also gets its smarts from the 9-volt.
You can’t really talk about smart smoke alarms without mentioning the Nest Protect, and the Roost has one big advantage over the detector from Alphabet: It detects natural gas in addition to smoke, fire, and carbon monoxide. The Protect has sensors for the latter three only. But Nest does have some advantages over the Roost in terms of smart-home inclusivity.
Wired
The Roost RSA-400 ($80) and the RSA-200 ($60) both need to be wired up to work properly. Roost recommends an electrician install your detector, as you’ll need to disconnect and reconnect some wires. It’s a shame Roost doesn’t have a battery-only option, as both Nest and First Alert do for their smart alarms. Roost says in order for its sensors to work, it needs to be hooked up to more than just a battery.
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