SmartThings and the Recirculating Pump

A couple of years ago, we got a recirculating pump to run the hot water line from the master bathroom back to the water heater so we could get actual hot showers. The pump came with a built-in timer so that we could schedule times for it to run. That’s swell if you live by the clock. But what if you take a shower at different times of day, or at times that are unpredictable? What you really want is a button or a switch in the bathroom (at one end of the house) that will turn on the pump (at the other end of the house) for long enough to get hot water (say, five minutes or so) and then turn it off.

Enter SmartThings. I actually found out about SmartThings from the channels list at IFTTT. I was looking at IFTTT to see if maybe I could make it turn on the stairwell light when we got close to the house. One could, if one had a SmartThings hub. So that’s where I started from, thinking about this pump problem. Got a hub, got a contact sensor, and got a switchable outlet. Now, to wire these things up so that the magic happens!

Only, I discovered that in order to apply any kind of logic to devices connected together with the SmartThings hub, I had to install a custom app into the hub. What? There’s a graphical display of all my devices, right there on my tablet, and I can’t drag a link from one to another? I can’t say, “Create new activity…” and get some basic logic wizard? WTF? Way to be dumb, SmartThings.

Okay, so here’s the solution: register as a SmartThings developer (it’s free) and write the logic in their almost-good web IDE. (I say, “almost good,” because it compiles on save and the only indication of syntax errors is that the save just never completes.) What language is it? Oh, you don’t need to know that. What are the keywords and operators? You don’t need to know that, either. (At least one error message mentioned Groovy, but I’m not sure if that’s the whole deal.) Anyway, I’ve now written an app that accepts a bunch of parameters (which contact sensor, which switch, what should the initial switch state be set to, what’s the final switch state, and how long is the countdown) and I’ve installed it in my house. Hooray! How do I share this app with the rest of the world? Beats me. Oh, wait, here’s the source!

/**
* Contact countdown
*
* Author: Stephen Beitzel <sbeitzel@pobox.com>
* Date: 2014-02-11
*/
// myContact - reference to the contact sensor that initiates the run
// mySwitch - reference to the switch we're controlling
// firstState - reference to the initial state of the switch
// finalState - reference to the final state of the switch
// delaySeconds - how long to wait

preferences {
  section("Initiate countdown from contact sensor") {
    input "myContact", "capability.contactSensor"
  }

  section("Initiate countdown on switch open") {
    input "mySwitch", "capability.switch"
  }

  section("Countdown this many seconds") {
    input name: "delaySeconds", title: "Seconds?", type: "number", multiple: false
  }

  section("Initial switch state") {
    input name: "firstState", title: "First set the switch to:", type: "bool", multiple: false
  }

  section("Final switch state") {
    input name: "finalState", title: "Upon reaching countdown, set switch to:", type: "bool", multiple: false
  }
}

def installed() {
  log.debug "Installed with settings: ${settings}"
  initialize()
}

def updated() {
  log.debug "Updated with settings: ${settings}"
  unsubscribe()
  initialize()
}

def initialize() {
  subscribe(myContact.contact)
  subscribe(mySwitch.switch)
}

def contact(evt) {
  log.debug "Contact event: ${evt.value}"
  if (evt.value == "open") {
    log.debug "Starting a new countdown"
    // set the switch
    if (firstState.value == true) {
      mySwitch.on()
    } else {
      log.debug("firstState.value is not equal to true, it is ${firstState.value}")
      mySwitch.off()
    }
    // schedule the countdown
    runIn(delaySeconds, countedDown)
  }
}

def countedDown() {
  log.debug "Counted down"
  if (finalState.value == true) {
    mySwitch.on()
  } else {
    mySwitch.off()
  }
}