Confused on 3 way switches - why is a zwave auxiliary 2-way switch needed?

A little confused here. I have a number of lights that are controlled by two switches. As I understand, This is because I have a 3-way switch with a primary and auxiliary. In order to control these lights using zwave, do I need to replace both switches with a zwave compatible device? An example below:

Or is it possible to just replace the primary with a 3-way switch such as the following?

What you currently have installed are two 3-way switches - they allow you to turn a light on or off from either switch location. If you want to use a Z-Wave compatible switch to replace them, you need to replace both. There are two ways to do this:

  1. With the GE product (or a similar product available from several other manufacturers) you provided a link to. One of these switches (the master) controls the actual load and performs the communication with Vera, the remote is designed to use the existing “traveler wires” between the two switch locations to control the master. A conventional 3-way switch cannot be used to control a Z-Wave master. You must use the remote specified by the manufacturer of the master - it is not a standard Z-Wave 2-way switch, and it is specifically designed to remote control the master using the in-wall cabling that currently exists between your two conventional 3-way switches.

  2. With the Linear WD500Z you provided a link to (which functions as the master) in combination with a WT00Z1 remote switch. The WT00Z1 uses Z-Wave to wirelessly control the WD500Z master - no existing wiring connection between the two is required.

Note the GE product you provided a link to is on/off only - but similar on/off/dimmer products are also available from GE and others. The Linear product you provided a link to is on/off/dimmer.

Good to know. So replace both switches. Thanks!

@bbohannon, because you’re unclear on the role of each switch, I feel compelled to clarify this:

In a conventional 3-way switch, either of the travelers can carry current depending on the position of the 3-way switches. when replacing this with multiple z-wave switches, only the master switch routes to the load–all slave switches simply signal the master.

In other words, the basic wiring layout is different. If you’re going to DIY this, please study the wiring diagrams until what I said makes sense.

also worth noting, most of the 3 way capable switches I’m aware of require a neutral (white) wire at the junction box. You almost certainly have one, but it’s worth double checking before purchasing.