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CMV FUNCTION WITH TIMETABLE AND/OR VOC SENSOR

CMV FUNCTION WITH TIMETABLE AND/OR VOC SENSOR

Owned by Marco Serpelloni
Last updated: Jan 03, 2025 by Giammarco Moceri
5 min read

The REG System can manage controlled mechanical ventilation (CMV) units both via timetable and via VOC sensor and via a combination of both.

For these functions it is necessary to load onto the REG-DIN-8 at least version 4.28 and a RegConfig version 4.28 must be used. 

Introduction

To manage CMV it is necessary to enable the CMV enable on the Configuration/1 - System Settings page:

as with other global enabling (DHW, System, and Seasonal set), the CMV can also be managed via an external dry contact on the CMV Enable Channel:

1. Timetable management

Once the CMV is enabled, we move on to timetable creation on the Dehumidifiers page, where for example, we choose to dedicate a Dehumidifier to CMV management, then in Auto Ventilation Function (CMV) we associate a timetable, e.g., timetable 04 “Ventilation”:

Then it is possible to set 3 speed values for the Ventilation (CMV): Economy, Comfort, and Boost. This setting can be made if the speed on the CMV is changed by the REG via the 0/10V outputs connected to a 0/10V input on the ventilation unity board.

Boost function is activated only when the Boost Mode Timer is different from zero (the value to be entered is the minutes for which you want the CMV unity to run at high speed). Once the time is exhausted, the unity will go back working in Economy or Comfort depending on how the timetable has been set.

In the Actual Status can be seen the tick on the renewal request if active and at what speed.

Finally, in outputs it necessary to associate (in the pages REGDIN OUTPUT or IO/A or IO/B OUTPUT) the dry ON/OFF contact as digital output and the speed as analog output:

The speed can also be sent to the CMV via digital output (low = economy; medium = comfort; high = boost).

Finally, on the timetables page within the associated timetable (in this case, Timetable 1 Living room), the OFF, Economy, and Comfort program can be set

2. Management via VOC sensor

VOC sensor (code REG-AQ-Sxx) must be configured with the address from 8A to 8F (as indicated in the product data sheet) without set (s/set) as it has no display and associated with a dedicated zone for renewal within the Zones – Configuration Zone/1 page; furthermore, the ventilation unit must be associated as integration unit:

 For this special zone, temperature and humidity readings and setpoints are interpreted in a particular way:

  • “Temperature” displays the current value of the VOC Index. When powered on, the VOC sensor reads a value of 40. During operation, VOC Index value below 40 (minimum 0,4) refers to improvement in indoor air quality; values above 40 (maximum 200) refers to deterioration in indoor air quality.

  • “Relative humidity” is not used and always displays as “N/C” reading.

  • The Comfort and Economy temperature setpoint are the VOC Index thresholds: typically, the Economy threshold will be lower than the Comfort threshold because the Economy air exchange speed is generally lower than the Comfort one. Specifically, if the VOC Index value exceeds the Economy threshold, the CMV starts at the Economy speed; if the Comfort threshold is exceeded, the CMV starts at the Comfort speed. To switch to the lower speed, the value must drop below the treshold/hysteresis.

  • The humidity setpoint represents the hysteresis of the VOC Indec for threshold transitions between Comfort and Economy, and from Economy to OFF

Therefore, it is the VOC Index variation that activates the Economy and Comfort speed once the thresholds are exceeded and switches the speed back to OFF or Economy if the value drops below the threshold/hysteresis:

The Economy and Comfort speeds are switched to the Dehumidifier page according to what is indicated in the integration column of the zone which has an associated VOC sensor (on the Zone – Configuration/1 page).

The configuration of the Dehumidifier page and the outputs (DO or AO) is the same as step 1, the only difference is that they are activated by threshold and not by timetable.

3. Combination of timetable and VOC sensor

If both point 1 and point 2 are configured on the same CMV, the speed and ON/OFF is determined by the OR condition between the two, so the timetable may be in OFF, but if the VOC sensor exceeds the Economy threshold, the CMV activates at Economy speed.

It is different if the timetable is directly associated with the zone and not in the dehumidifiers page: in this case, the timetable and the threshold operate in AND, then if the timetable is in OFF and the VOC sensor exceeds the Economy threshold, the CMV will not be activated.

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