Thermostat

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The principle

Up to 24 thermostats can be activated for Heating as well as for Cooling. When Heating mode is activated, only the heating thermostats are active, the same applies for cooling. Also the Daikin airco units with RTD-10 control board are supported by Openmotics. For more information, see Heating/Cooling pages.

Every thermostat has 1 temperature sensor and 1 or 2 outputs linked to it. Every thermostat also has a current setpoint and multiple preprogrammed setpoints. The preprogrammed setpoints can be copied in to the current setpoints by using Basic Actions or when the thermostat is in automatic mode (driven by the timings per thermostat and per day)

When the current setpoint of a thermostat is higher than the temperature measured by the sensor linked to this thermostat (in Heating mode), than the thermostat will drive his outputs. The way the outputs are driven is determined by the thermostat PID parameters. Every thermostat has his own set of PID parameters (for heating as well as for cooling) that can be adapted to the size and behavior of the room and the type of heating. For more explanation regarding the PID parameters , see PID page.

A thermostat can be configured with 1 or 2 outputs. When 2 outputs are chosen, the thermostat will first drive the first output. When the room doesn’t heat or cool fast enough (using the PID parameters), the second output will be driven. A typical example is that the floor heating of a room is connected to the first output, the second output will be used for a traditional convector that is added to the room for faster warm up. Any dimmer output or relay output can be used as the thermostat output.

2 modes can be used:

  • Automatic
  • Manual

When the system is in automatic mode, the current setpoint will be automatically changed (by copying the preprogrammed setpoint in to the current setpoint) depending on the time (and the day of the week) and in which mode the themostat has been set (heating or cooling). Every thermostat has 3 preprogrammed temperatures that are used in automatic mode, those temperatures are different for heating and cooling:

  • Preprogrammed setpoint 0 -> Day 1 temperature: This is the temperature used for the first part of the day
  • Preprogrammed setpoint 1 -> Night temperature: This is the temperature used when not in day 1 or day 2.
  • Preprogrammed setpoint 2 -> Day 2 temperature: This is the temperature used for the second part of the day.

These temperatures can be set per room (thermostat) and can be different for every day of the week.

Manual mode has also 3 preprogrammed setpoints per thermostat:

  • Preprogrammed setpoint 3 -> Away: This is the temperature used when not home for a short period of time
  • Preprogrammed setpoint 4 -> Vacation: This is the temperature used when not home for a longer period of time
  • Preprogrammed setpoint 5 -> Party: This is the temperature used when having a party


For every thermostat, the timings can be programmed per day (for heating as well as for cooling) as described in following example:

   Thermostat 0: (prepr setpoint 0: 22.5, prepr setpoint 1: 17.0, prepr setpoint 2: 22.0)
       Monday
           Day 1: 7:00 – 10:40 (will use preprogrammed setpoint 0 – day1)
           Day2: 17:30 – 22:50 (will use preprogrammed setpoint 2 – day2)
           The rest of the time will use preprogrammed setpoint 1 – night 
       Tuesday
           Day 1: 6:00 – 8:30 (will use preprogrammed setpoint 0 – day1)
           Day2: 19:30 – 23:30 (will use preprogrammed setpoint 2 – day2)
           The rest of the time will use preprogrammed setpoint 1 – night 
       Wednesday
           … 
   Thermostat 1: (prepr setpoint 0: 20.0, prepr setpoint 1: 16.0, prepr setpoint 2: 18.0)
       Monday
           Day 1: 6:00 – 7:00 (will use preprogrammed setpoint 0 – day1)
           Day2: 17:30 – 19:20 (will use preprogrammed setpoint 2 – day2)
           The rest of the time will use preprogrammed setpoint 1 – night 
       Tuesday
           Day 1: 6:00 – 8:30 (will use preprogrammed setpoint 0 – day1)
           Day2: 20:30 – 22:00 (will use preprogrammed setpoint 2 – day2)
           The rest of the time will use preprogrammed setpoint 1 – night 
       Wednesday
           … 


When you change from automatic to manual or vice versa, this will be done for all thermostats. When the thermostats are in manual mode, the current setpoint is kept and the preprogrammed timings are ignored.

An outside temperature sensor is used to determine when the full thermostat system goes in off mode (only in Heating mode). You can program an outside temperature threshold that, when reached, the thermostat goes in off state. For example, you can set the threshold on 18 degree Celsius, when the outside temperature is higher than 18 degree, the system will go in off state even when the current setpoint is higher than the room temperature. When the system is in cooling mode, the outside temperature will not switch off the cooling system.

The system can also drive the pumps of your heating and cooling system. Multiple pump groups can be created. All the valve outputs that are driven by the same pump will be put in the same group. Each pump group will be linked to an output to drive the pump for that group. When 1 of the valve outputs is driven, the pump output will be activated

For example, I’ve 2 pumps in my house, 1 for the main floor and 1 for the first floor. I will use 2 pump groups and I will put all the valve outputs of the main floor in pump group 0 and all the valve outputs in pump group 1.

The pumps can also be delayed when slow valves are used.