Most smoke alarms can't tell the difference between steam from the shower or smoke from a fire, so they treat them both the same way. This is one of the things we thought we could do better with Nest Protect.
How Steam Check works
To develop Steam Check, Nest tested and recorded steam-generated alarm incidents in the lab, as well as in real home settings. After measuring the differences between steam related events and fire or smoke events, we developed a software algorithm to detect steam related events and reduce nuisance alarms they can cause, while keeping the same level of sensitivity for fire and smoke.
We've found that Steam Check can reduce nuisance alarms from steam on Nest Protect by over half.* Sometimes, being smart means keeping quiet.
Does Steam Check mean Nest Protect will never alarm if there’s any steam?
Steam Check won't stop all alarms related to steam. If the event appears similar to real smoke or fire, even if it's caused by pure steam, the alarm will sound. When this happens, you’ll need to address the source of the steam and air out the room for Nest Protect to quiet down.
However, on most days, you won’t even notice Steam Check
How can I enable or disable Steam Check?
Steam Check is on by default, but you can enable or disable
*Based on Nest's internal testing and data