No, I don’t have a stutter. I’ve been frustrated with the lack of a z-wave smoke detector that uses the US z-wave standard. I’ve been trying to figure out an option for doing this, and thought that maybe I would just keep my normal smoke detectors, but rig something to detect the state of those smoke detectors.
I happen to have a smoke alarm and CO detector system that has an interconnect wire that goes between all of the smoke detectors so that if one alarms, they all alarm. I read that the alarming detector will put a 9V signal on this interconnect line. So, I bought a 9V relay ($1.50 on ebay model JQC-3F) and wired it to an Aeon Labs wireless door sensor that I sacrificed for this project. I liked the idea of using the Aeon door sensor because then I didn’t need to worry about power outages or running new wiring. The door sensor reads in normal state when nothing is going on and tripped state when I connect the load wires of the relay to a 9V battery. I’m planning to plug it into one of my detectors, when my kids aren’t all asleep, to make sure it works properly.
I am not an electronics guru and this is a total hack job. I’m just wondering if anyone has any opinions as to why this might be a bad idea or why this might somehow actually cause my house to burn down or something similar.
Actually I find it a good idea.
A minimum of 55 euro for a zwave smoke detector. Compared to cheaper mainstream one with a zwave sensor. Makes sense.
But after intensive searching (fibaro universal sensor) and a traditional smoke or co detector with an “external signalling” option, I gave up. Now I plan to buy zwave detectors.
But… if your option works… it’s worth investigating the total cost.
Only drawback… you can not differentiate “which detector dtected”… it’s all or nothing…
Shrubber, I think this is a Great idea, and wondered about doing the same.
I’m thrilled to see you try it first. 
The advantage to this method is you gain ZWave notification of ALL your smoke detectors, which is significantly less cost than replacing every one with a new ZWave smoke detector.
I wasn’t aware that the third-wire inter-detector signalling was 9v. If you can, might want to put a scope or at least DVM to see what the signal looks like. If it’s a digital signal between detectors (doubtful) or something lightweight (no drive strength), then you might have to boost the current with a switching transistor before it can activate a relay.
Looking forward to your test results. I see that the Schlage Door/Window sensor also has a pair of screw terminals inside for dry contact, so that’s a second option.
Not only can you sense these … If you Supply the 9Volts via a Z-Wave relay … to the third wire you can signal your smoke detectors. Voila … whole house alarms! I do it!
I don’t know if the third-wire signaling is universal, but USI offers a dry-contact relay adapter for this purpose:
Universal Security Instruments USI-960 Relay
Bump any follow-up on this?