OpenHAB Heating Rule

heating.rules

import org.openhab.core.model.script.ScriptServiceUtil

val heatingZones = newArrayList(
  "livingRoom",
  "bathroom",
  "masterBedroom",
  "spareBedroom",
  "office",
  // etc...
)

rule "Heating: turn heating zone virtual items on/off"
when
  // every 5 minutes, offset by 10s to make sure the target temperatures have been set above
  Time cron "10 0/5 * ? * * *"
  or Member of gc_targetTemperatures received update
then
  // this rule does two passes over heating zones:
  // - the first pass decides what kind of call for heat to issue (see below)
  // - the second pass applies changes to the virtual items for whether heating is enabled in that zone

  // there are two kinds of calls for heat: firm and soft
  // zones with a firm call for heat will always receive heat (i.e. radiator turns on, boiler turns on)
  // zones with a soft call for heat will only receive heat iff there is at least one firm call at the same time

  // firm/soft calls are determined based on how actual and target temperatures combine with the hysteresis value to create 4 cases:
  // case 1: actual temp is more than <hysteresis> below the target
  // - firm call for heat
  // case 2: actual temp is within <hysteresis> below the target
  // - if the zone is on (i.e. we're climbing through this case) then make a firm call to keep it on
  // - if the zone if off (i.e. we're falling through this case) then make a soft call
  // case 3: actual temp is within <hysteresis> above the target
  // - if the zone is on (i.e. we're climbing through this case) then make a firm call to keep it on
  // - if the zone if off (i.e. we're falling through this case) then don't call for heat
  // case 4: actual temp is more than <hysteresis> above the target
  // - don't call for heat

  val Number tempHysteresis = 0.5
  val itemRegistry = ScriptServiceUtil.getItemRegistry

  val softHeatCalls = newArrayList()
  val firmHeatCalls = newArrayList()

  heatingZones.forEach [ String zone |
    val Number zoneActualTemp = itemRegistry.getItem(zone + "_temperatureHumiditySensor_temperature").state
    val Number zoneTargetTemp = itemRegistry.getItem(zone + "_targetTemperature").state
    val boolean zoneEnabled = itemRegistry.getItem(zone + "_heatingEnabled").state == ON

    var String callType = "none" // just for logging

    if (zoneActualTemp < (zoneTargetTemp - tempHysteresis)) {
      // case 1
      callType = "firm"
    } else if (zoneActualTemp < zoneTargetTemp) {
      // case 2
      if (zoneEnabled) {
        callType = "firm"
      } else {
        callType = "soft"
      }
    } else if (zoneActualTemp < (zoneTargetTemp + tempHysteresis)) {
      // case 3
      if (zoneEnabled) {
        callType = "firm"
      }
    } else {
      // case 4: do nothing
    }

    if (callType == "firm") {
      firmHeatCalls.add(zone)
    } else if (callType == "soft") {
      softHeatCalls.add(zone)
    }

    logInfo(
      "heating",
      "Evaluating {}: target = {}; actual = {}; enabled = {}; new heat call = {}.",
      zone,
      zoneTargetTemp,
      zoneActualTemp,
      (if (zoneEnabled) "on" else "off"),
      callType
    )
  ]

  logInfo("heating", "Finished evaluating zones. Firm calls = {}; soft calls = {}", firmHeatCalls.toString(), softHeatCalls.toString())

  // apply on/off states to zones
  heatingZones.forEach [ String zone |
    val boolean turnZoneOn = firmHeatCalls.size() > 0 && (firmHeatCalls.contains(zone) || softHeatCalls.contains(zone))
    sendCommand(zone + "_heatingEnabled", if (turnZoneOn) "ON" else "OFF")
  ]

  // apply on/off state to boiler
  garage_boiler_callForHeat.sendCommand(if (firmHeatCalls.size() > 0) ON else OFF)
end