Is the Protect "replace by" date precise?

[phk46]

I have four Nest Protects that will be expiring over the next couple of years. I know I need to replace them, but I would like to eek as much life out of them as possible. So I would prefer to wait until they expire before replacing. One of them will be a real pain, because it is on a cathedral ceiling, 12' up. I don't have a ladder that can reach it. It may take me days or weeks to find one to borrow.

What will happen when it expires? If it is like other smoke detectors, it will make annoying noises until disconnected. Is there a way to remotely tell it to shut up until I can get it down? If not, can I trust that it will wait until its reported "Replace by" date before it starts complaining?

[David_K]

Hi @phk46 

To meet certification standards, Nest Protect must be replaced when it's sensors expire or after 10 years from the date of manufacture, whichever comes first, so the "replace by" on the packaging is 10 years from the date of manufacture.

When Nest Protect sensors expire, even if that's before 10 years it will chirp. The chirp acts as a reminder for you to take action, and is in fact required in order to comply with safety regulations. In both of these situations, Protect chirps continuously until the issue has been taken care of and as it is a safety critical device there is no way to turn it off.

When to replace your Nest Protect - Google Nest Help

[phk46]

@David_K, thanks! The info on the "When to replace" page is helpful. If I can rely on these warnings to give me at least the stated amount of lead time, then that will meet my need for time to arrange to replace it.

You seem to say that the sensors *might* expire prior to the "replace by" date. If so, that would make the warnings less helpful. How likely is it to expire before the "replace by" date?

I ask about this because I had a prior smoke detector (before the Protect) expire in this location, when I had no ability to reach and remove it. That was incredibly annoying (in a bedroom). I ended up using a long board to beat it to death to get it to stop beeping.

[David_K]

That's an impossible question to answer. The "Sensor damage" section of that help article explains things that can damage the sensors and cause them to expire early, and here's guidance on how to clean Protect because like any smoke alarm, dust build-up on the outside or inside can damage your Nest Protect.

Clean your Nest devices - Google Nest Help

[phk46]

@David_K, I gather there are two reasons that can cause the Protect to stop working and start alerting that it needs to be replaced: 

1) it could be damaged. This could happen at any time.

2) it can reach its "expiration date", which is ten years after its manufacturing date.

I'm asking only about (2). Can I assume that this is precisely the date that is reported out by the app? How does it determine when it has reached this date? Does it depend on NTP? Or does it "dead recon" the date via an internal clock, that might drift from real time over ten years?

[David_K]

As another user, I don't have the answer to that deep technical question unfortunately.