When you select a thermostat in e.g. a Tastu Display, RoomMate or SWC0xT or click on "properties" in a thermostat switch, the following thermostat screen will be displayed.
This screen shows 5 thermostat programs including manual control. By (un)checking the fields right below the program names, you can select which programs you want to control from the control on the switch.
The “Time Off” box can be used to have the system switch automatically from Economy or Comfort to Night after a number of minutes when selecting the program manually.
Also see 'Global IGeneral I/O parameters/O parameters'
Via tab “Advanced” more additional parameters can be set.
The "boost" option can be used if you have an additional valve or circuit that you can control to heat the room faster. In that case you may want to add heat from this second controlled heating unit (boost heating = heating coming from both units) if the difference in degrees between the set value and the measured temperature is greater than e.g. 2 °C.
The "hysteresis" refers to the difference in degrees required to turn on the heating system. This prevents the heating and cooling from switching on alternately when you control both heating and cooling. For example, if you want the heating to operate when the temperature is less than 20 degrees and the cooling is activated at a temperature above 20 degrees, it will continuously switch between cooling and heating. If you set the hysteresis to 0.5 degrees, the heating will start from 19.5 degrees and the cooling from 20.5 degrees.
With the "alarm" option, set the maximum and minimum temperatures and select whether you want to close a contact (this can be done via the relay) or create an alarm that you can send via your mobile phone (if you have an SMS module) or via ethernet (if you have an ethernet port on the controller).
From CTD FW3.09 you can also limit the set point. It is not possible to have the set point deviate further from the set point of that program. A setting of 5°C thus limits the set point between 17°C and 27°C when the Comfort regime of 22°C is active.
Intelligent Heating / Cooling (Qbus PID)
PRINCIPLE
The Qbus intelligent Heating / Cooling works on the basis of PID control. The controller calculates the difference between the desired temperature (set point) and the room temperature, and will control the heating depending on the magnitude of this difference. We call this Intelligent Heating / Cooling or Qbus PID control.
The Intelligent Heating / Cooling works as follows:
1) The difference between the room temperature and the desired temperature is calculated (“DIFF”);
2) The time to change the temperature 0.5 degrees has been calculated (TIME)
3) The DIFF value and the TIME value are multiplied by the GAIN (see below) to calculate the proportional value that the heating system will control.
During each proportional step, a fine-tuning mechanism based on the Integrator value will speed up or slow down the heating or cooling process. See below for more explanation about the integrator value.
The Qbus intelligent heating / cooling works as shown below. Both heating and cooling are activated when the room temperature differs 0.5 degrees from the desired temperature. A “dead zone” between heating and cooling must avoid continuous alternating between cooling and heating: when the room is heating and the desired temperature has been reached, cooling can only start when the room temperature rises above the dead zone (adjustable via the Qbus configuration software) has increased.
CONFIGURATION OF THE QBUS PID CONTROL IN THE SYSTEM MANAGER
Once PID is selected the thermostat screen will change as shown below. CLICK THE “DEFAULT” BUTTON AT THE TOP RIGHT TO USE THE DEFAULT VALUES FOR THE QBUS PID CONTROL. IT IS RECOMMENDED TO USE THESE STANDARD VALUES DURING FIRST PROGRAMMING AND ADJUST THEM AS NECESSARY BASED ON THE EFFECTIVE RESULTS OF THE CONTROL.
Integrator: both for the relay and 0-10V-based Intelligent Heating/Cooling. The integrator value is added to the control value (= calculated as DIFF x TIME x GAIN) to smooth the control. The higher the integrator value, the flatter the curve, causing the control process to react more slowly. We recommend that you do not change the integrator value at system start-up and only adjust this value if necessary after the system has been in operation for a while.
Gain: Used to calculate the heating/cooling proportional control value (DIFF x TIME x GAIN; see explanation above). The higher this value, the greater the jumps in the checking process will be to speed up this process). A gain that is too large can result in an overshoot. Again, we recommend using the default value of the gain in a first stage and only adjusting it after using the system for a while.
Delay: is only used with relay-based Intelligent Heating/Cooling. When relays are used to control heating and cooling, a 10-minute cycle is used to go through the process. Since a relay can only be open or allowed, e.g. a relay that is 75% open is translated by opening this relay in the cycle for 75% of the cycle time (=7.5 minutes) and for 25% of that time (2.5 minutes). Since most electronic thermostatic valves have a delay from fully open to fully closed (usually about 3 minutes), the “delay” time indicated in the “delay” field is added to the 10-minute cycle time to minimize the effect of this “slow effect” to filter out thermostatic valves.
Button2 on DIS01: when the Qbus PID is active and this field is on, the second button on a DIS02IT can be used to switch the cooling off or on.
Speed 2: only when the difference between room and set temperature is higher than the number of degrees stated in “Speed 2” an extra relay can be switched on for additional heating or cooling. Speed 2 is an I/O that can be assigned to a relay or 0-10V control module.
PID Minimum / Maximum: describes the range that can be used for manual temperature control via touch screens or switches. When a temperature lower than the PID minimum temperature is selected in a thermostat program, the cooling will never be activated. This is to prevent, for example, the air conditioning being used to cool down a room during the night or when you are absent.
Dead zone: dead zone between heating and cooling: when cooling is off, the room temperature must be lower by at least the number of degrees stated in this field before the heating is switched on. Conversely, it should be that number of degrees warmer than the set point before cooling starts. See also figure 3 above for an example.
Events: The events are on by default. Next to this button is the interval at which these events can be forwarded. We recommend choosing an interval of no less than 2 minutes.
CONFIGURE I/O’S WITH QBUS PID
Configure relay outputs
By creating a Qbus PID thermostat, four I/O’s are automatically created: Heating, Cooling, Speed 1 and Speed 2. These I/O’s can be assigned to relays.
Heating and Cooling must be assigned to the relay to which the valve, controlling them, is connected. Speed 1 and Speed 2 must be assigned to a fan if there is one present. Speed 2 will only work if the difference between the room and requested temperature is at least the number of degrees assigned to Speed 2 in the PID screen.
Configure analog (0-10V) I/O’s
Since the Speed1 / Speed2 I/O’s are ON/OFF contacts, they can only be assigned to relays, not analog I/O’s. Only the Cooling / Heating contacts can be assigned to some 0-10V I/O modules.
USING QBUS PID IN COMBINATION WITH ANALOGUE LOGIC
When a PID thermostat mode has been created you will find following I/O’s in the list of I/O’s that can be used in analogue logic:
Thermostat (Setpoint):
Set point (requested temperature) of this thermostat; it can be used as a condition: (IF Setpoint = X degrees, THEN…) or as a consequence (If X is ON, then set Setpoint to X degrees)
Thermostat (RoomTemp.):
Room temperature measured by the thermostat sensor; can only be used as a condition
Thermostat (Prog):
Respective program (Comfort, Economy, Night, No Clock,…) of the thermostat mode; can be used as a condition or as a result.
Thermostat (TimeOff):
the Time-Off function of the respective thermostat program; can be used as a condition or as a result.
Thermostat (Heating):
if the "Heating" I/O of the thermostat mode is on (too cold) or off (warm enough); used as a condition
Thermostat (Cooling):
if the "Cooling" I/O of the thermostat mode is on (too warm) or off (cold enough); used as a condition
Thermostat (Speed1):
if the I/O “Speed 1” of the thermostat mode is on or off; used as a condition
Thermostat (Speed2):
if the I/O “Speed 2” of the thermostat mode is on or off; used as a condition
Thermostat (HeatingPWM):
if the “PID Heating” I/O of the PID control via RELAY is on or off; used as a condition
Thermostat (CoolingPWM):
if the “PID Cooling” I/O of the PID control via RELAY is on or off; used as a condition
Thermostat (HeatingAnalog):
if the “PID Heating” I/O of the PID control via ANALOGUE MODULES (0-10V) is on or off; used as a condition
Thermostat (CoolingAnalog):
if the “PID Cooling” I/O of the PID control via ANALOGUE MODULES (0-10V) is on or off; used as a condition