I found a very instructive YouTube video titled “Connecting a Ring Pro Video Doorbell to the electronic chime in a Nutone intercom” dated 8/20/2018. It explains (shows): How doorbells work in general and are wired; how to wire up a Ring Video Pro to a regular doorbell; AND how to wire up a Ring Video Pro to a Nutone intercom in a manner that still causes to Nutone Chime to play when the button on the Ring Video Pro is pressed.
The video is quite instructive and the process does not appear to be complicated. I don’t have anything to try to sell to anybody, so I’m just going to try to explain it to you below.
You must purchase an AC Relay to act as a “trigger” for the chime on the intercom system (that’s all that the doorbell pushbutton you have now does, but by attaching the Ring Video Pro to those old doorbell wires, you’re effectively removing that “trigger” that used to send a signal back to play the chimes. so this relay serves as a new “trigger” to start the intercom’s chimes to play). The video includes a screenshot from Amazon showing a 24V AC Relay that can do this and it’s under $10.00.
If you happen to also have an actual 16-24v doorbell transformer (your intercom doesn’t have one), then you may not need to buy anything else. [I’ll add here that I’ve seen a few posts from folks saying that sometimes a 16v transformer isn’t quite enough with the Video Pro, but they also report that a 24v transformer works great.]
However, if (like me) you have only the intercom (mine is a Nutone IM3003) system with its chime and NO separate doorbell transformer, then you’ll need to get a transformer, too. Again, the video includes a screenshot of an appropriate (24V 40VA) AC transformer that’s only about $20.00. (I found a different one on Amazon with the same specs, but that comes with 25’ of wire already neatly attached. It’s not much more & saves a little work).
That video includes hand drawn electrical diagrams for all three of the wiring possibilities noted above, along with showing him testing with a multimeter during the video to illustrate what’s going on, so you can really learn, rather than just following a list of steps, but not really understanding what you’re doing.
What I don’t understand is why Ring doesn’t offer an optional product that combines such a relay and a transformer in one little box and sell it for $29.99? Lord knows the parts would be cheap enough to buy in volume and the wiring is simple.
While watching that video, I took some screenshots to help me remember what to do (and buy), then I plugged those into a Word document with a few minimal “reminder” annotations, then made it a pdf file.
Thinking you may find it useful, I’ve attached a copy of that pdf file here. But I know it’s going to be better if you’ll find and watch that video itself.
So you’ll know: I didn’t make the video and I don’t know they guy who did. It just seemed good to me.
Install Ring Video Pro Doorbell to Work With Electronic Intercom System.pdf (616 KB)