Smoke/CO Z Wave?

Not sure why a decent smoke/CO detector is so hard to hunt down, but I’m having a hard time finding a suitable integration to ST. Ideally I’d like to integrate into my existing smoke detectors which are hardwired in my house. I’ve seen some misc. posts about the Halo detectors working well with others, but can’t be sure. Nest seems a nonstarter as I’m not buying 4x of those. AND they don’t hardwire.

First Alert has a Z wave device on amazon, but I can’t tell it it’s a discontinued product or not.

Then there’s the relay option, where I’d add in a relay to my existing wiring and it would pick up on the alarm trigger. This would be great, other than not adding CO alarms to my system.

This item works fine but is sometimes on sale.

  1. It cannot be hardwired.
  2. The Z-Wave version doesn’t interconnect with other units.
  3. You cannot trigger the siren on this unit from SmartThings or anything else.
  4. The low battery alert should occur at 77%, cuz after that it won’t report the final drop to SmartThings.

So why bother?

  • Cheap (often)
  • Reliable basic functionality
  • Still can trigger SHM or other SmartApps which are valuable if you are away from home or want to automatically turn on all the lights or activate separate Siren unit, etc.,

The First Alert 2-in-1 Z-Wave Smoke Detector and Carbon Monoxide Alarm is carried at Lowe’s. Although they advertise it as “Works with Iris”, it is the same model that works with SmartThings.

Nest Manager is a very good community developed integration for the Nest platform (thermostat, Protect, and Dropcam), but it is dependent upon the cloud and an internet connection.


At our house I use the relay solution for our interconnected, hardwired Kidde smoke alarms. Seems to work fine and, as @tgauchat mentioned, I have an automation to turn on the lights if it alarms.

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Halo is actually a great option IMO. I bought my first one late last year and with the recent firmware update integrates into the whole home alarms.

I bought my second one and it will arrive tomorrow. I place to have one Halo on each floor and then do basic hardwired for the rest.

Highly recommend Halo…


I’ll have to look into this more. Any tips or good posts you can point me to?

I saw that Halo notes that they can be integrated with existing hardwired alarms. They just don’t guarantee they will work with every brand’s interconnect. I might grab one and try it just to see if it works. Seems to be a pseudo way of doing the relay, since it would basically be the beacon to ST in the event of an alarm.

I took the Nest off the table since I’d have to buy too many smoke alarm: cost prohibitive. It also seems counter productive to not use the existing interconnect wiring in the house. Thinking resale down the road.

This is the best option. No need for new, potentially unreliable detectors (I bought a pair of the first alert detectors, which F’d my system up for some reason). The install was as much as a single first alert detector, but now I have all of my alarms harnessed.


Just ordered the Halo. I’ll report back when I get it installed.

I replaced all 11 of my zcombos with Halos and couldn’t be happier. No batteries to replace (almost twice a year with the zcombos, and they start chirping just below 80% battery), they’re interconnected, and they have a cool LED ring that makes for a great night light.

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Over $1500 USD, unless you found a great bulk-buy sale?

I’m definitely glad you love them; and always interesting to find out that not all folks buy SmartThings because it is the low-budget smart home system.

Not quite. I just got the Halo, not the plus.

Legit discounts, gift cards, and using Amazon points to buy Lowe’s cards helps.


The basic idea is shown in the link @Nhaley already posted! I used a different contact sensor I had on-hand, but otherwise as shown…

Complete newbie here with very little knowledge (yet). Been following this thread and liked the idea of adding the contact with a simple sensor. As I have old smokes that have to be changed, decided to look to see if anything had an integrated contact in it already. Found the Gentex line does (sold @ Home Depot). Pretty much anyone of their Smoke detectors that has a part number that ends in “F” (i.e 9123F) will have a form C dry contact. Should only need to monitor 1 as when the first goes, they will all go (at least that’s what I think at this stage) and the contact will be opened/closed.

Just want to monitor for a second home, don’t care which one is going off, just concerned if any are going off.

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Just installed the Halo smoke/co alarm. Oddly, it paired incredibly quickly to smartthings but the Halo app didn’t pair.

Still need to test to see if the interconnect works with my existing basic (Kiddie?) smoke detectors.

Initial findings:

  • It reads the temp and humidity, which I didn’t know. However, the temp is 7 degrees (F) above what my thermostat says. Assuming the humidity is wrong also.
  • Smartthings allows you to control the base LED color.
  • Seems like the smartthings app can replace the Halo app completely.

Glad you were able to set the device up quickly to ST. I thought I’d offer some clarity on the halo app.

At this time, You can connect via ZigBee (ST) or Wi-Fi (Halo App) but not both. We worked closely with SmartThings where you wouldn’t miss much functionality.

Our FAQ is here:


old post I know but for others reading this in the future… You are right in that Nest detectors are expensive. But they do interconnect to each other using their own wifi protocol so that isn’t an issue. Also the interconnect wire stays in the house and just gets capped off. Additionally, smoke detectors are supposed to be replaced at least every ten years so the whole angle about resale is a moot point.

Editing update…Nest states to replace theirs at 7 even though the accepted normal recommendation is 10.

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I’m curious how a home inspector would view detectors that are all Nest that sort of require an app a buyer may or may not know how to use (even though it’s dead simple). Might turn off some potential buyers vs a simple Kiddie interconnect. Just something to think about. May not be something that actually adds value to the home like we’d assume. I think about this a lot with my smart light switches that require a smartthings hub and Alexa to really work simply, which 9/10 people don’t know how to use intuitively without previous experience. It takes some “training.”

At least with the Halo’s they are wired interconnect like any other system. Assuming all detectors are Halo’s and interconnected, it seems like more of a complete/working package. That’s ultimately why I ended up with the Halo’s in my house.

Just thinking out loud here…


good question. The Nest detectors only require initial setup with the app so they can talk to each other though. After that the app is no longer needed.

I have to make a change to my previous statement of having to replace detectors after 10 years. The nest website says to replace theirs at 7. I am pretty sure they probably are set up to just stop working at 7.

If anybody thinks any of this smartstuff or nest detectors or nest thermostats or remote opening garage doors adds any value to a house purchase they are delusional.

A house purchase isn’t going to be derailed or close because of a $40 light switch, or even several.

Definitely not adding value to the house. I’d call it a nice feature at best, assuming somebody like us is the buyer lol. In fact, some might be turned off by it. That’s what I meant.

7 years wouldn’t surprise me.

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