Z-Wave and me...

For some time I have been thinking about creating a set of .NET classes that abstracted out interactions with home automation devices, the ControlThink guys have since done a pretty good job with their Z-Wave SDK but I think its a practical necessity to be able to interact with devices based on many different protocols and having a set of abstract base classes for each device type with implementations of those base classes for each device class (like we did with System.Security.Cryptography in the .NET Framework) would be a nice way to accomplish this.

I figured I would start small and hook a couple of devices up, I started with my fireplace (gas, electric ignition) and its fan so it would be controllable via Z-Wave (and my Harmony 890); with that in mind I ordered a pair of the Leviton 15A Z-Wave switches (one for my fan and one for the ignition on the fireplace).

Hooking up the fan was a breeze, I had to hook up the neutral (which surprised me since Z-Wave is RF based) but turns out the ignition on gas fireplaces are actually millivolt based, thus my switches are incapable of controlling the fireplace; there are two reasons for this:

1. These switches require 120v power to operate, and only the low voltage wiring is present.
2. These effectively bridge the incoming 120v signal to the load on the switch when toggled, thus if I were to just run the 120v over to this location and hook it up I would at best kill the ignition as its not expecting 120v input or at worse blow up my house.

When I had this realization I started looking for a switch designed for this scenario unfortunately I could not find one, this leaves me with a few options when it comes to finishing this wiring project:

1. Find and purchase a single pole, single throw (SPST) power relay with a 120v coil and spring return, run 120v power to the switch location wire the coil in as the load, wire the millivolt into the load on the power relay.
2. I was able to find a generic Z-Wave relay that says its input power is isolated from the load, in theory I can run 120v to under the fireplace, then extend that circuit to the switch location, put the relay under the fireplace and put a Z-Wave companion switch in the switch location.
3. I can see if (with some help from a EE friend) if I can modify the 15A switch to suite my needs without the addition of a external power relay (#1).

I really wanted to finish this project off this weekend so I headed over to North Coast Electric and then Platt Electric to see if I could get the SPST relay I would need for that approach and both indicated they would need to order it so I decided to sleep on it and place a order this next week.

In the mean time can you think of any other solutions?

Print | posted on Saturday, September 15, 2007 1:39 PM