Tag Archives: z-wave

Attacking The Electric Bill, Pt. 2

Nice ViewWhen my wife and I moved from Hilo back to Maui, we looked into buying a house, but settled on a nice townhouse condo at Ho‘ole‘a Terrace, just outside Wailuku on the road to Waikapū. One of the few drawbacks of this choice (see one view to the right) is that we don’t have the option to add photovoltaic or solar water heating panels. I have written previously about our attempts to get our electric bills under control in our old home in Kurtistown, and these limitations proved to be motivation to find other ways to lower our electric bill.

The water heater for our unit is in a ground floor storage room that we are forbidden from entering without advanced approval from the management company. Fortunately, the circuit breaker for the heater is in our unit. We’ve been manually turning it on and off to save electricity, but you know how that goes–some days we forget to turn it off when we leave in the morning, or when we go to sleep at night, or forget to get up early to turn it on to have hot water for morning showers.

Mi Casa Verde LiteI considered adding a simple, mechanical timer to the circuit, but also wanted to get a grip on other appliances that unnecessarily drained electricity. After looking at various X25 and Insteon units, I decide to get a Z-Wave system from Mi Casa Verde called VeraLite. It looked like it had a pretty nice web interface with flexible programming, and could be accessed via my mobile phone. There also seemed to be a nice selection of receptacles, switches, web cameras, door locks, sensors, and other devices that could be controlled from this unit. So I ordered one and several receptacles.

Elk 9200The next task was to find a 220v relay for the water heater. It turns out there is no receptacle or any other Z-wave compatible device that can control a 220v appliance. I did find this Elk 9200 220v relay that could be controlled by a 110v Z-wave receptacle, so I ordered on of those as well. At this point I needed to call in a pro, but opted to call in my father instead. Hehe. The Elk relay was a bit bulky and housed in an unecessarily large white metal lock box. The excessive size turned out to be a blessing, and it was large enough to hold a receptacle box.

GE Zwave receptacleWe pulled another line from the breaker panel to power the relay, connected the water heater’s line to the other side, and brought in another 110v circuit to power the Z-wave receptacle outlet that controls the 220v relay. Confused yet? Dont worry, we were for a while, too. What we figured would take about two hours turned into a five hour job, but hopefully it’s worth it.

Mi Casa Verde’s MiOS web interface turned out to be not as intuitive as it seemed at first glance, and took about a half hour to figure out. Their docs are not that great, and lack any really helpful examples or explanation of their scenes, triggers and schedule, or at least how they are interconnected. But I set up the heater to come on in the morning, turn off after two hours, turn on again in late afternoon, and turn off again in the evening.

The next step was to find an Android app that works with the VeraLite, and House Buddy turned out to be the winner. I simply logged into my account on Mi Casa Verde’s site, it automatically showed all of my “scenes” and devices. Turning the water heater relay on or off from my HTC One V was almost instantateous.

KillAWattMonitor_DetailThe next step was to seek out vampires… vampire loads, that is. Vampire loads are devices that use electricity even when they are not in use. The power supplies that come with just about everything we own use electricity all the time, though in recent years they have gotten much more efficient. I pulled out my trusty Kill-A-Watt, as I had done at our old home, and began sleuthing. The technician from Time-Warner Oceanic cable that installed our equipment warned me against using anything to power down their devices for any length of time as the system updates it frequently, and if it were powered down during an update it could disable the unit and require service. A quick check with the Kill-A-Watt showed that all of their devices combined, as well as our Apple Time Machine, cost about $20 a month to operate. Figuring someone is in the house and probably using the Internet about 60% of the time, the cost saved by  powering these units off didn’t outweight the inconvenience of having to get a disabled device working again.

My CPAP uses about $5 a month just being plugged in as it has one of those block DC power supplies like many printers do. That will be the next to receive a Z-wave controlled outlet so the power supply will be disconnected during the day. Another nice feature of these receptacles is that they have a button on them that allows you to turn them on if they are off, or off if they are on. Pretty handy. Until I get a computer desk and some of my other equipment online, it doesn’t seem that there is much else worthy of the cost of these recepticles. The electric bill for the first full month in our unit was $127, so I’ll report back when I figure out if this was worth the time and effort we put into doing this.

And thanks, Dad!