PSA: Check out your smoke detectors (once every 10 years)

Tuesday, June 20, 2017

I have owned my house for just about a year now and I have been automating and ‘smartening’ it up like crazy.  My home automation platform of choice is Home Assistant.  If you haven’t checked it out, it’s an Open source platform that runs on a raspberry pi and becomes the glue or in VMware terms, the abstract layer between all the various hardware.   Yes.  I have a software defined house.

So last month, I got to thinking about my smoke detectors.  I have quite a few of them in the house and honestly didn’t know much about them.  I knew 2 of them were connected to my alarm system and the rest were hardwired into power.  There was also an interconnect wire between them all so that if one goes off, they all go off.  I learned this when one of them went into a low battery state and triggered them all to go off. at night. on a week day.

In addition to the ‘dumb’ status they held, I also learned after some googling that ALL smoke and carbon monoxide detectors go bad after 10 years.  They have a chemical pad in them that ‘smells’ the smoke or CO and then triggers the alert.  This chemical has a 10 year effective lifespan.  My current detectors were 14 years old (they have a manufacturer date stamped on them) and basically didn’t do ANYTHING except eat batteries and then chirp for more.  The house could be on fire and they wouldn’t respond unless a battery happened to fall out of them.

Image result for nest protect

Of course, they needed to be replaced and I went with the Nest Protects.  They are not the cheapest guys on the block but I think they are the smartest and were the easiest to integrate into my existing smart home.  By code, I needed 9 of them for the house.  1 in each room, 1 in all bedroom hallways and 1 in the kitchen.  The ones I purchased are hardwired into power and use a wireless interconnect to spread the word of danger.  You can read up on all the cool nest features elsewhere so I wanted to just share the couple of small additions I made to my set up.

Home Assistant already had a Nest component so once I set them up on the network and added them to my Nest account, all the various protect sensors just showed up in the interface.   My Nest package can be found in my Github repo here.

Out of the box, if the Nest Protects sense an emergency condition, they will of course alert you but additionally, they will

  • turn off your HVAC (assuming controlled by a Nest Thermostat)
  • turn on your sprinkler system (if controlled by a Rachio system)

Thanks to Home Assistant, mine will also trigger my emergency script.  The script sequence will

  • switch all outside lights to red to indicate an emergency
  • flash all lights in the house 4 times to grab everyone’s attention (although the piercing siren from the detectors should do that as well)
  • turn on all interior lights to 100% brightness in the house.
  • switch my front LED strips to a white flashing strobe
  • open both garage doors if we are home. (via Garadget) [Not implemented yet]

It’s been about a month with the Protects and no false alarms so I’m pretty happy with that.  The guide light feature is a welcome bonus as well.

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