ref: adt security panel vista 20
how can i re-use existing adt door/window sensors in a zwave home security configuration?
I assume that the wireless door/window sensors will need to be replaced. do i need a LV relay for each hard wired sensor? what about the smoke/heat sensors? how do i set up an “away” scene to call me if a breach?
i also assume that the siren can be reused by using a relay.
I had the same concern. Zoos provided zero support with this issue so used wireless door contacts
I still think it can be done with a relay and power supply
RVF
This is a good topic I think should be discussed more. There are really two levels of question here: 1) can you do this technically, and 2) should you do this.
There are multiple schools of thought on if you should ‘home grow’ any system that provides life safety to you, your family or your employees. Once you get past that, then there are different opinions (and laws, codes, compliances and insurance issues) depending on if you are talking about burglar alarm vs fire/smoke/CO. Also where you live is a significant factor as well.
For anyone to offer assistance that may cause someone to unknowingly cause a danger to human life or violate a code or standard I think they would tend to shy away from providing advice at all. If that person is a licensed burg or fire professional, the liability for assisting with any home grown workarounds can be significant. I think that is why you are finding some silence on this topic, unfortunately.
From my perspective, fire safety is the most important and I’d never home grow anything in that regard. So if you have a Vista today with smoke and heat detectors, I’m guessing these are 2 or 4 wire sensors being powered by the Vista. There really isn’t a ‘home automation’ solution for that system. You’d either need to implement a different system of detectors that is approved by your local building and fire codes, or perhaps, implement a UL Listed/Certified replacement for your Vista system. Actually the Vista systems are still rock solid and can be purchased and self installed and self monitored in DIY fashion with great success.
On the burg side - if you don’t want/need monitoring and prefer a local ‘noisemaker’ and ‘notifier’ type alarm, there I feel there is more flexibility. You could leverage your replacement UL listed system (Vista?) used for your fire sensors to retain connectivity to existing wireless and wired sensors, and then integrate that sensor data into your home automation in a number of ways. This would depend on which zwave hub you are using, of course.
Alternatively, if you use the Vista (or whatever you go with) for fire only; you could certainly home grow a ‘notifier’ type burg alarm with z-wave parts and pieces and home grow the solution. In that case, the wireless sensors you may have today with the Vista would be unusable and likely should be replaced. The wired sensor zones could be connected to a variety of z-wave inputs but you’d lose sensing of trouble on any of the zones. For that I’d recommend a series of ZEN16’s for the most relays per dollar spent.
Edit to add:
For the siren, yes you could use one of the relays on a ZEN16 to control the 12v siren.
For the outcall to your phone, there are auto-dialers which can be triggered a number of ways (likely by closing a circuit on another ZEN16 or similar relay output) by various manufacturers but require other tech such as a POTS line or ability to make an IP based SIP call, etc. An example is a Seco-Larm E-922CPQ.
[I will say once upon a time I self-monitored my security system with an auto-dialer to my cell phone. Then I had a real burglary event and I realized that was not for me. I’ve had pro monitoring ever since… but I know everyone’s situation is different.]
Sorry for the long response. I hope this was helpful.
Spot on as usual & I agree on all points. “If it matters, go professional.”
Our home has a monitored, professional burglar alarm. Our code-compliant interconnected smoke alarms (no outside monitoring) also have a ZEN55 Smoke/CO Detector Bridge who’s job it is to turn on lights if the alarms go off–a convenience, not a necessity.
Funny. That’s what exactly what use my zen55 for! 
I also have a firefighter module (listens for t-3 cadence) that relays the alarm from the line voltage detectors to my monitored system. Plus other smokes heats and COs that are part of my monitored IQ based system. The joys of an older house.
I’m slightly more paranoid and less so when it comes to gadgets and what’s easy to deploy (low cost tech with short installation service calls) vs really secure. So I may not be the right person to chime in, but I know enough about breaking technology and what bad actors do nowadays to know you mitigate risk knowing things will fail and you should be highly confident that experts say it’ll function in life safety moments. Life Safety Systems MUST be certified to rely on them. Don’t mess with them. Supplement them with a parallel system. And, stop reading now if the remaining post is going to send you into a fit of paranoia. 
I HATE professional systems that aren’t hardwired. I had to argue with ADT at my last place because I wanted the “more obsolete” system because the installer didn’t want to run wires in a professional manner. So I paid more for a system that always worked, without visible wires. That didn’t depend on batteries that weren’t changed on time or who’s power supply fluxated between a cold unoccupied house and one that’ was warm and tosty in the winter.
Trusting radio signals from devices comes with variables I won’t count on - be it WiFi interference, “cycling” questionable appliances or electronics, or normally “coexisting” z-wave systems (like your hub and the alarm panel) that run into issues when one or the other has a busy moment. How many times have we had a device report not make it back or an automation trigger properly?
Many of these things are improved or resolved by Z-Wave Plus or LR devices. With that, my trust?? or rather tolerance means I do rely more on them for secondary purposes.
Deciding how your critical system reports back for monitoring is important as well. Many IP and VOIP systems have not been deemed reliable enough to become life safety certified. Cellular notifications, hardline backups to IP based solutions are smart for mission critical. Both still can and have failed.
Don’t trust cloud-based solutions. I’ve toyed with a now-bankrupt cloud automation provider, and another that finally is doing more local after swearing by the cloud - until they failed miserably. Find a hub (my father uses ZBox, I use Hubitat right now) that is 100% off-cloud (or optionally cloud-extended) for better reliability. There are dozens of factors outside your or your vendor’s control that could cause your cloud-based system to fail in a critical moment.
I currently use Nest for my smoke alarms (until they expire as it’s EOL) but check out PLACE as my current advanced alternative. While you’re likely integrating via a Cloud API (open or psudo-closed), there’s a plethora of information a good device can supplement with your automation system. Build a parallel notification system using something like the ZEN 55 as @getoffmylawn and @Barkis did.
Now, throw in the fact that we have modern burglers that scan for and clone your car’s proximity key all while standing outside as you get your well needed sleep. This tech isn’t obscure, so unless it’s a random smash and grab, your burglar probably uses a radio frequency jammer and makes the effort to rip out your cable or fiber internet openly mounted on the side of your house. 
Just like locks, this stuff keeps your average “good” person from breaking in. And, a home automation that turns on lights and unlocks doors when the smoke alarm goes off, or starts flashing all the lights in the house when a contact opens will probably do the job of alerting you and making your house less interesting to rob. It’s really about adding another layer on top of that “certified” system, and both are better together than no system. If somebody’s willing to stand by the liabilities with life safety device certifications, use their system. Some even have extra open/close contacts you could put a zwave relay on to detect and report burglary to your home automation system. Don’t fit your home grown device or hack in to the core system if you depend on it. Build next to it.
This is all fantastic advice. The important part here - whether speaking in terms of your home or business security, life safety or even cyber security/IT (which is my day job, btw) - is having layers. if any one component or layer is compromised, hopefully another layer is there to provide some level of warning, alert or otherwise to indicate there is (or may be) an issue.
It’s very important.
However for some of this it does come down to risk level vs likelihood vs available budget and at a certain level compromises may be needed. In my case, for instance, I do have wired sensors but my panel is all wireless (PowerG and 319.5) so they terminate in a takeover module.
But it does have other layers - dual path Wifi plus cellular for alerting, frequency jamming alerts where panel will alarm if jammed while armed (although it is a little slow to detect), smash and grab protection (where if someone rips the panel off the wall and runs away with it, it alerts via cellular and records a video of the panel itself while the guy is running away with it), and lastly, the camera system is separate, UPS battery protected, and records to the cloud, to an onsite NVR and to onboard SD Cards at the same time. So hopefully, somewhere there might be a usable video. And all of this for a very sleepy suburb where (knock wood) it is more likely to have annoying solar salespeople than intruders.
But all that said - twice I gave my video footage to the police to help a neighbor with an issue they were having!
It’s hard to find a hardwired sensor based system that has good tech features (which is why I use the system I do… it was a choice). However at my office (for my business) it is good 'ol fashioned 100% wired security; hardwired cams, door access, etc. no wireless at all. On top of that is Home Assistant with Z-wave for temp monitoring and lighting, appliance and HVAC control. HA can sense alarm states via a few hardwired relays.
Yes, layers with redundancy are the best answer we have. You and I @getoffmylawn have the same approach to the problems as I am also in the SaaS operations/cyber security/networking world by day.
All my cameras are local stored and stream offsite too. None with storage inside the device that likely will be ripped off the wall or damaged. Recent national news support this reality too. Let alone the question of “where’s your video stored, how’s it used, and how come they could retrieve it weeks later.”
So, buy a trusted system, balanced price point, integrate it if you can. Add parallel systems where you don’t get what you want, but don’t invalidate a monitored system with local “technically it should work” changes! Sorry for the divergence through the detailed weeds.
None of us, inclusive of Zooz can assume liability/responsibility for modifications of monitored packages that are certified as such and often remain silent for that reason. If you can ask your alarm installer to wire in your relay to a dry contact as a secondary alarm device, that’s probably the closest you’ll come to getting somebody to stand by extending your panel to home automation. But its unlikely they’d do so.