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Increasingly, in thermal systems designed for space heating, cooling and dehumidification, there are simultaneous heat exchange, treatment or air renewal terminals with different operating principles (such as heating bodies, radiant floor or ceiling panels, fan coils, dehumidifiers, VMCs with integration of sensible supply in cooling, etc.) that make it necessary to produce heat transfer fluid at different temperatures. This can be done directly in the heating plant or locally by controlling a mixing unit.
| Ekinex devices | Other system components |
| A) Mixing group controller EK-HH1-TP | 1) Mixing group |
| B) NTC temperature sensor (external) EK-STE-10K-3435 | 2) Mixing valve with servomotor |
| C) NTC temperature sensor (immersion) EK-STI-10K-3435 | 3) Circulating pump (mixed zone) |
| D) NTC temperature sensor (immersion) EK-STI-10K-3435 | 4) Circulating pump (unmixed zone) |
| 5) Boiler room manifold (flow) | |
| 6) Boiler room manifold (return) | |
| 7) Thermal generator (warm fluid) | |
| 8) Thermal generator (cold fluid) |
Control with Ekinex
The unmixed zone directly serves the heat exchange terminals with heat transfer fluid at the temperature produced in the heating plant. The EK-HH1-TP controller (A) controls the mixing unit (1) by adjusting the flow temperature of the heat transfer fluid for the mixed zone.
For this purpose, the mixing valve (2) equipped with a servomotor and the circulator (3) of the mixed zone are controlled, acquiring the flow temperature by means of an immersion probe (C). Optionally, the return temperature can also be detected by means of a second immersion probe (D).
The outdoor temperature probe (B) measures the outdoor air temperature for climate-compensated control. In the case of radiant panel systems that are also used for summer cooling, the ideal use of the controller (A) is in combination with up to 16 EK-EQ2-TP room thermostats equipped with temperature and relative humidity sensors to achieve effective integration between central (primary) and room or zone (secondary) control. In this way, the switching on and off of the system as well as the optimal flow temperature of the heat transfer fluid are automatically selected according to the actual indoor conditions of the building; in cooling, the optimal flow temperature with active protection from condensation phenomena can also be selected.
| Control options | Heating | Cooling |
| Fixed point | √ | √ |
| Climatic compensation | √ | √ |
| Adjusting to internal conditions | √ | - |
| Adjusting to return temperature | √ | - |
| Climatic compensation and adjusting to internal conditions | √ | - |
| Adjusting to internal thermo-hygrometric conditions | - | √ |
| Climatic compensation and adjusting to internal thermo-hygrometric conditions | - | √ |
Focus on the EK-HH1-TP mixing group controller
The EK-HH1-TP controller (A) is a KNX device, fully programmable via ETS, which allows the flow temperature of the heat transfer fluid to be regulated in heating and cooling hydronic systems.
The device can be used as a stand-alone unit or in combination with one or more Ekinex® room thermostats to create single-zone or multi-zone systems (up to a maximum of 16 zones), controlling the servomotor of a 3-point floating mixing valve, powered at 230 Vac or 24 Vac, or with 0-10V signal and controlling the circulating pump of the mixed circuit in run / stop mode.
The device manages over-temperature (in heating) and under-temperature (in cooling) alarms. The controller has a backlit LCD text display, four membrane buttons for navigating through the display menu and two LEDs for alarms and switching to manual mode.
The display allows the operating parameters to be monitored; some control parameters can also be modified with respect to the initial configuration carried out with ETS. The switch-over of the system conduction mode (heating / cooling) can be done from the bus, from a digital input (configured for this purpose) or manually from the front keyboard. Alarms from anti-condensation probes can be managed. The digital outputs, not used to activate a circulating pump, can be configured to control a zone valve servomotor located on a circuit dedicated to fan-coil units or dehumidifiers.
To create automation logic, the device is also equipped with 2-channel logic functions (16 inputs per channel) with exclusive AND, OR, NOT and OR blocks and delayed activation of the corresponding output.
Inputs and outputs
| Terminal no. | Label | Connection |
| 3-4 | IN1 | Input 1 (fl ow temperature sensor) |
| 5-6 | IN2 | Input 2 (return temperature sensor) |
| 7-8 | IN3 | Input 3 (outdoor temperature sensor) |
| 9-10 | IN4 | Input 4 (confi gurable as AI or DI) |
| 11-12 | IN5 | Input 5 (confi gurable as AI or DI) |
| 13-14 | A01 | 0-10 V control output for servomotor |
| 15-16 | POWER AUX | TRIAC power supply (230 Vac o 24 Vac) |
| 17 | CLOSE | Control output for servomotor (closing) |
| 18 | COM | Control output for servomotor (common) |
| 19 | OPEN | Control output for servomotor (opening) |
| 20-21 | D01 | Relais output circulator input |
| 22-23 | D02 | Relais output (additional functions) |
| 24-25 | D03 | Relais output (additional functions) |
Switching the seasonal conduction mode
The seasonal (heating / cooling) mode can be switched in three ways:
- from the KNX bus;
- via the front keypad of the controller;
- by means of a switch connected to an input of the controller.
If switching from the KNX bus is selected, the controller receives the conduction mode from another bus device (via a communication object), such as an ekinex® room thermostat, which has been assigned the master function for seasonal switching.
Switching can be carried out manually using the keypad and the display on the front of the device: in this case, it is the EK-HH1-TP controller that performs the master function of seasonal switching for all Ekinex devices (sensors, actuators) that are on the same system or part of a system served by the controller.
Switching via a switch connected to input IN5 (configured as DI) is suitable for standalone applications in which there is no need for integration between the boiler room (primary adjustment) and the rooms or zones (secondary adjustment).
The switch can be the same as the external selector used in the boiler room for switching the operation of heat generators or shut-off valves of fluids. The current operating mode is stored in the non-volatile memory of the controller.
Activating the mixing group
The mixing group can be activated in three ways:
- from the KNX bus;
- from a controller input;
- from a controller input and the KNX bus.
By selecting the activation from the KNX bus, the controller connects in logical OR the flow requests coming from a maximum of 16 Ekinex room thermostats. To activate the mixing group it is sufficient that a single room thermostat requires flow.
The activation from an input is suitable for stand-alone applications in which there is no need for integration between the boiler room (primary adjustment) and the rooms or zones (secondary adjustment). A time programmer can be connected to input IN4 to activate the group according to scheduled time slots or the request of a standalone room thermostat.
In systems with distribution manifolds, the limit switches of the electrothermal drives mounted on the individual valves can be connected in parallel.
An intermediate solution, on the other hand, involves activation both from the binary input and from the KNX bus. The input can have priority over the flow requests coming from the zones via bus (for example an external time zone programming device) or it behaves as an additional zone (without priority).
In all cases it is possible to set an activation delay (from 1 to 255 seconds) for the start of mixing; in fact, it is advisable to wait for the electrothermal drives to bring the valves into the open position to prevent the circulating pump from exerting pressure on hydraulically closed circuits.