Zooz Z-Wave Plus Smoke and CO Zen55 detector for hardwired systems

Just wanted to share as this has been something I’ve been looking for a long time. There are z-wave smoke detectors available, but none for a hardwired system. I’ve tried audio listeners before that listen for a dumb detector going off, but I’ve not had a lot of luck.

Enter the Zooz Z-Wave Plus Smoke and CO detector Zen55. Very much like other z-wave relays you can wire into switch boxes, it’s small Relay and just connects to the Line, Neutral, and Traveler wire used in most hardwired smoke detector systems. I was able to install in around 10 minutes, and then could see the smoke and CO status in HA. Regardless of what detector was set off, it was able to report it. When I tested my smoke detectors, I did notice it had some trouble separating smoke and CO signals, but it never missed the detector going off. The site mentions its pretty new, and future firmware updates may be coming, so possible that will improve.

Just wanted to share, as I’ve seen requests for smart smoke detectors that were hardwired before, and this seems like a good option.


Good to hear. I picked one up during their last sale, just haven’t got to that item on my to-do list.

What’s been your on-going experience with the Zen55? I’m looking at using one to integrate my wired smokes with HA

I haven’t seen any issues out of them but I also don’t make it a habit to start fires in the house so YMMV :laughing:. They have worked reliably when using the test feature on any of the smoke detectors.

Thanks. I ordered one to monitor my seven hard-wired, linked smoke detectors

I read in the installation manual that is need to be installed in the last smoke detector. Is that your experience? Not super excited about unmounting a dozen detectors to find which one is at the end of line - as you know it’ll be #12 :tired_face:

It can be installed anywhere. They just recommend the last one since it will have the most box space.

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Thanks for highlighting the ZEN55! I just installed one to monitor my smoke/CO alarms. It was pretty easy - just triple check then use a multi-meter to check again to ensure you’ve turned the power off to the alarms before you start.

The unit shows up as two binary sensors, one for smoke the other for CO. I’ve set up automations if either sensor becomes true to 1) turn off my HVAC systems, and 2) send an alert to my phone if I’m away from home. (I figure if I’m home, I won’t need a phone alert along with the alarm blaring…)

The documentation emphasizes several times that the ZEN55 “is NOT part of a life-safety system”. So definitely think of it as a supplemental notification of an alarm event, not as an alternative to or replacement for an actual smoke alarm.

I have a mix of just smoke and combination smoke/CO detectors. Can I install it any box, and the CO alarms will send the signal to the interconnector wire to the relay?

Edit: to answer my own question, yes the relay can pick up the CO alarm independently from the interconnect wire, so it can be installed along side just a smoke alarm,

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I changed my mind and ordered an Ecolink FF-ZWAVE5-ECO . You place it near a Smoke/CO detector and it listens for alarms. I tested it and it detects smoke and CO alarms

@tombo12354 and @FriedCheese, I am considering this sensor. I cannot seem to find the input specs for the red wire, the ‘S’ input. That is, what voltage range does it accept? AC or DC? The sensor is named a ‘DC’ sensor but the documentation also states that it is compatible with all ‘standard’ smoke detectors.

From my experience (was an electrical engineer in the past with lots of experience wiring my home lights, switches and outlets), “Standard” in houses in the US for 120VAC powered smoke detectors is that the link/relay signal is also 120VAC and not a DC voltage. Therefore, I am a bit confused with the letters, “DC” in the name of the Zooz device.

I have reached out to Zooz with my question. They have acknowledged my question but need to talk with their engineers first. Their reply seems to be taking a long time and I thought one of you might be able to confirm what voltage your detectors relay out to the other detectors that the ZEN55 is monitoring. If you are not sure, what brand and model of smoke detectors might you have? I can find it from there.

I could just buy one and if the documentation has the wrong voltage for my detectors, return it. It just seems that it would not come with the info in the box (or I would be able to find it online) and I might smoke a $30 sensor, ‘just trying it’ if it is expecting a much lower voltage.

I could test, but I’m about 99% certain that the signal wire uses DC voltage to signal an alert, but the actual voltage is dependent on smoke detector model. A quick Google search says the voltage depends on manufacturer but usually ranges between 5-9V. So, yeah, it stands to reason that the S-input is DC.

The input power for a smoke detector would be whatever your residential power supply is (120V for the US).

If I had to wager a guess, this thing is just a slightly modified ZEN51.

So your reply and the reply from Zooz arrived at the same time. Yes, I was wrong. The signal on the red wire in the US is a DC signal and not 120VAC signal that I had assumed. Nice to learn something new. I am ordering the ZEN now! Thank you for your confirmation. Much appreciated.