King Thermostat

King Thermostat (Pro) is the app's own thermostat. It keeps the room where you are within a band you pick, by starting and stopping the heater, like a home furnace: full power until the room reaches the target, then off, and on again once the room has cooled by the swing.

Setting it up

1. Tap King Thermostat under the dial on the Heater tab (it's on the Automations tab too).
2. Set the target and the swing. They're kept while it's off, and nothing is sent to the heater.
3. Turn it on. It starts the heater right away if the room is already at the ON temperature or below.

Use one thermostat at a time. The Switch to Heater Thermostat button hands control to the heater's own thermostat, which goes by the sensor in the heater, not the room. If an RF thermostat also starts and stops the heater, King Thermostat steps back each time it does.

The band

• Target: the temperature it heats the room to. When the room gets there, the heater turns off. Drag the handle on the dial, or use − and +.
• Swing: how far the room may cool before the heater starts again. Target 74 °F with a swing of 3: ON at 71 °F, OFF at 74 °F.

The dial shows the band, for example "ON 71 · OFF 74".

How it runs the heater

• By default it runs the heater at Power Level 10 (the run level). It never switches the heater into its own Heater Thermostat.
• Before a start, it sets the heater to Power Level at the run level while it is still off (on heaters that allow that).
• Hold the run level: if something changes the level during a run (the heater's panel, a remote, an RF thermostat that sends ON twice), the app puts it back. Change it twice at the heater and your change is kept for that run.

Which temperature it uses

It runs on the room temperature from the sensor you pick: the Phone sensor, a Bluetooth thermometer, or the heater's own sensor if the heater takes its air from inside. See Room temperature.

With the Phone sensor, leave the phone still in the room, out of its case and out of the heater's airflow: a table or nightstand overnight, ideally on its charger, is ideal. Nothing to set up; a thermometer reading can fine-tune it. Heavy phone use (games, video, long calls) warms the phone more than the app can take off, so the reading can run high until it cools. A Bluetooth thermometer is the most precise.

Without a fresh room reading it doesn't start the heater, and a running heater is stopped. It never runs blind.

Safety nets

• It turns off a little early when the room reading trails the room (the Phone sensor does), so the room doesn't run far past the target.
• If the heater takes its air from inside, it ends a run when the heater's own sensor rises a lot during it (8 °C or 15 °F by default). With outside air that sensor says nothing about the room, so this limit isn't used or shown.
• If the heater doesn't light twice in a row, it pauses and tells you.
• It never starts the heater while Stay-Off is on, during a CO alarm, or while the heater reports a fault.

Your heater, your call

• Change the heater in the app and King Thermostat pauses. Tap Resume when you're ready.
• If the heater is turned on or off at its panel or with a remote, the panel wins: King Thermostat pauses and tells you (unless Settings Guard's Keep running is on).

Advanced

• Style: On/Off (the default) starts and stops the heater at the run level. Steady turns the Power Level up and down instead. Hybrid turns it down, then turns it off if it's still too warm.
• Overshoot: let the room go a little past the target before turning off.
• Minimum run time (20 minutes) and minimum rest time (10 minutes) spare the burner short runs: it doesn't stop a run before 20 minutes, and it waits 10 before starting again. Safety stops never wait. You can turn them off.
• Starts per hour is off unless you set it. Your heater's manual may recommend values.

Same help as in the app (More → How to use).