D350 DucoBox Energy Comfort Plus Balance Ventilation Device User Manual

June 9, 2024

D350 DucoBox Energy Comfort Plus Balance Ventilation Device
User Manual


The DucoBox Energy Comfort Plus D350 is an individual mechanical ventilation unit with heat recovery.
Demand-controlled balanced ventilation/heat recovery unit with supply and exhaust fan, equipped with intelligent frost protection, modulating bypass and a high-efficiency  plastic cross-flow heat exchanger. The new DucoBox Energy Comfort Plus D350 combines very quiet operation (thanks to the metal casing) with a high flow rate and  efficiency within a very compact unit thanks to the unique dynamic airflow filters.
The semi-automatic adjustment, by means of unique pressure measurement via the internal sensors, ensures a quick and durable installation of the unit and guarantees a  qualitative calibration. Here there is a time saving of 60 % for the installer and a consequent cost reduction.
By integrating a copy function into the software, it is possible to take over the settings within similar houses in serial construction. This again saves time for the installer.
Since the product is 100% left/right interchangeable, this makes this low- threshold heat recovery unit a very easy  product for the installer to order because of only 1  reference. This reduces the margin of error as well as stock management to an absolute minimum. In addition, all existing Duco sensors and/or user controls are compatible  with this new heat recovery unit, due to its modular principle.
Additionally, the unit is future-proof when using the Connectivity Board. This allows interfacing towards home automation and building management systems via REST API  (locally or via the cloud) or ModBus TCP (locally). Both are possible via Ethernet or WiFi. The Connectivity Board also allows the use of the Duco Installation App, which  enables the installer to adjust the Duco System (with implementation quality assurance in function of government obligations (e.g. STS in Belgium or Quality Assurance Act  in the Netherlands)). For the end user, this means that he can also control his Duco system remotely via his smartphone or tablet.


The unit supplies fresh air mechanically to and extracts stale air mechanically from the home with the help of integrated fans. During this process, the heat is recovered from the extracted air and transferred to the air supplied.

Casing: coated sheet steel
Inside: PP, ABS (without thermal bridges) and closed-cell insulation material (EPP)
Integrated heat exchanger: plastic (100 % recyclable; manufactured from recycled material)


Connections:| The air ducts for the home connection can be connected at the top of the DucoBox Energy Comfort Plus D350. 4 Top connections (in EPP):
Outdoor air to the house Extraction from the house Exhaust to the outside Supply from outside
Air connections: 4 x Ø 180 mm female
Exhaust duct from the unit to the outside: Insulated duct
Quantity (pcs.): 1, individually
Outdoor air supply duct to unit: Insulated duct
Quantity (pcs.): 1, individually
Number of zones supply side:| The 1-zone system with demand control ensures extremely quiet, intelligent and energy-efficient operation.
Optional, compact and quick to install 2-zone valves provide the most energyefficient result that can be achieved with a heat recovery system.
Frost protection:| Equipped as standard with an automatic intelligent energy- efficient frost protection by means of speed  control on supply/temporary imbalance and flow restriction. This ensures frost-free operation of the DucoBox Energy Comfort Plus D350, guaranteeing proper ventilation during the winter period.  Alternatively via an optional external heater.
Variant:| 1 product reference = the product is 100% left / right interchangeable (by the software)

Technical specifications:

(Total) flow rate (m³/h):| Maximum 350 m³/h 200 Pa, adjustable according to the calculation of the contractor / installer / preliminary  ventilation design, in accordance with legal standards.
Discharge head (Pa):| 200
(Temperature) efficiency (%):| At 350 m³/h: 84 %
At 307 m³/h: 85 %
At 255 m³/h: 86 %
According to EN 308-1997
Sound power level (Lw/dB(A)):| Casing radiation (dB(A)): 56.5
Supply (dB(A)): 74.5
Extraction (dB(A)): 57.5
Flow rate (m³/h): 350
Pressure (Pa): 200
Dimensions (mm):| W: 760
H: 803 (including connections)
D: 584 (including mounting bracket)
Weight (kg):| 47
Fans:| The direct current EC fans have robust backward-curved blades, making them easy to clean. The fans are  vertically mounted and very quiet. The unique positioning of the fan, namely in front of the heat exchanger,  ensures optimum noise reduction on the supply side.
Fan type:| EC
Type of heat exchanger:| The cross-flow heat exchanger is characterised by low resistance, which also contributes to minimal noise and  energy consumption. The heat exchanger consists of polystyrene.
Energy class:| A+ (in combination with 2 sensors = control factor 0.65)
Air filter/Dust/grease filter:| Supply and exhaust side, standard equipped with dynamic airflow filters coarse 65% (ISO 16890) (class G4) –  supply optionally ISO 16890 ePM1 55% (class F7). The filters are easily accessible and removable through a  filter drawer mounted at an angle. The filters in the DucoBox Energy Comfort Plus D350 are electrostatic and anti-bacteriological. They filter the air from pollen and coarse and fine dust.
The filters are selected for a replacement period of 6 months.
(Supply) voltage (V):| 230 V, 50 Hz
Electrical connection:| Equipped with 2 m cord with earthed/Euro plug
Protection rating:| IP 40
Colour:| white + green
Surface treatment:| Coated (sendzimir galvanised)
Condensate drain:| A condensate drain (with pipe diameter 32 mm (1 ¼”) externally integrated / threaded) is provided for the  drainage of condensation water. This condensate drain should be connected to the indoor sewer via a water  trap (siphon) with a minimum level difference of 60 mm.
Connection of the condensate drain to the drain line is by means of a siphon with a sufficiently large water  trap, e.g. Siphon flat.
Two are provided: depending on which version one chooses (left or right), the other must be closed.


Settings:| Adaptive / demand-driven, can be expanded with humidity sensor and/or CO2 sensor.
Customised demand control based on sensors that can be linked modularly.
– Time control: Possibility of programming a fixed time schedule.
– Absence mode: In the event of prolonged absence, the absence mode can be activated so that the ventilation system runs at the most energy-efficient mode.
Control:| Direct current constant volume with flow control, always guarantees balanced air flows and flow rates are kept constant.
Automatic calibration:| The DucoBox Energy Comfort Plus D350 unit is equipped with a constant volume control. The set air flow rate is automatically controlled independently of duct resistance and filter fouling.
(Summer) bypass:| Double automatic 100% modulating bypass as standard. Can be operated automatically or manually.
The bypass operates fully automatically based on indoor and outdoor temperature measurement. The bypass directs the air around the heat exchanger. In this way, the house is naturally cooled during summer nights.
NightBoost:| With DUCO’s standard NightBoost function, the ventilation system is deployed during summer to support the cooling of warm indoor temperatures. This fully automatic, smart (night) cooling function temporarily deactivates demand control and causes the system to operate at nominal value. Not only does this reduce the risk of overheating, it also reduces cooling requirements. Smart NightBoost algorithms ensure energy-efficient operation without disturbing night rest.
Filter notification:| The unit is equipped with an automatic filter notification, based on the amount of ventilated air. When the filters need to be replaced, the LED on the user control lights up orange when the control is operated. The filter notification can be reset via the RF switch sensor.
– Via smartphone
– On integrated control unit
– On optional external user control
– Time-controlled
Calibration/operation:| 4 modes: low, medium and high; automatic mode.
– Position 1: 10 % of the nominal position
– Position 2: 50 % of the nominal position
– Position 3: nominal position (100%) (to be set)
Communication:| Wireless communication via RF protocol with other control components in the DUCO network.
Wired communication via DUCO protocol, 5 x 0.75 mm²   with solid core (feed 2 x 0.75 mm²+ communication 3 x 0.75 mm²(A-B-GND)) with other control components in the DUCO network.

User control:

  • With integrated user control
  • Indication of active programme
  • Possibility to adjust the necessary parameters

Mounting bracket for wall mounting
Installation guide
User manual
2 x dynamic airflow filters coarse 65 % (ISO 16890) (class G4)
Expandable with Connectivity Board for the purpose of:

  • Operation via Duco Installation App
  • ModBus, PWM-IN, PWM-OUT, Switch contact (3x), Ethernet (possibility to control the DucoBox Energy
    Comfort Plus D350 via tablet/smartphone), Micro SD card slot Humidity sensor (Energy Comfort (Plus))

Mounting chair standing (Energy Comfort D400/Plus), for easy mounting on the floor Siphon flat (Energy & Eco)
Filter set 2 x Coarse 65% (Energy Comfort D400/Plus) Filter set Coarse 65% / ePM1 55% (Energy Comfort D400 /Plus)
Design flow rate:

  • Flow rates in accordance with applicable legislation
  • Place air supply points in the walking zone as much as possible
  • Use ‘clean sector’ vents at air supply points < 30 cm from the wall
  • For air supply points ≥ 30 cm from the wall, if possible use standard vents

Control and switching equipment:
Manual operation via display
User controllers with RF communication
User controllers with wired communication
Manual operation via time control
Sensors with RF communication such as CO2/RH
Sensors with wired communication such as CO2/RH
Presence detection by means of the Switch Sensor with RF communication
Presence detection by means of a voltage-free contact on the control card Humidity reading via measurement in the duct
Control components can be paired with the DucoBox Energy Comfort Plus D350 (= master unit).
The individual mechanical ventilation unit with heat recovery for (residential) application with an operating volume of 350 m³ per DucoBox Energy Comfort Plus D350 at 200 Pa. Applicable as standard in the following DUCO ventilation systems: Duco Energy Comfort System Plus D350
Location: According to manufacturer’s prescription supplied. Indoors with measures taken to meet legal noise requirements.
Location: In the attic/in the central heating cabinet/in a closed installation room. In the technical room (e.g. above washing machine)

  • The DucoBox Energy Comfort Plus D350 is suitable for both wall and floor mounting.
  • On a solid wall (minimum mass 200 kg/m²) by means of suspension bracket provided
  • To be placed on mounting chair


  • Connections with ducts
  • Extraction side, rigid and fixed extraction, as straight and direct as possible to the outside, 190 mm
  • Sound-absorbing facilities between the unit and the connection ducts to and from the home
  • 1 metre of flexible acoustic hose
  • Finishing with armaflex tape
  • Roof side: thermally insulate the duct vapour-proof between the heat recovery unit and the roof feed-through for both exhaust air and outdoor air
  • House side: flexible sound-absorbing duct between both extraction and supply duct and the heat recovery unit

Connection method: For commercial and technical assistance (assembly and installation instructions), please contact your regional dealer or the DUCO Ventilation & Sun Control project department.
Service and maintenance:
For service and maintenance, maintain a minimum service space of 500 mm in front of the heat recovery unit. The DucoBox Energy Comfort Plus D350 is easy- to-service since all components are accessible from the front.
Standard: 24 months from production date
After online registration or DUCO VIP: 36 months from production date
The unit described above complies with the relevant European Union harmonisation legislation:

  • Machinery Directive 2006/42/EC;
  • Radio Equipment Directive 2014/S3/EU;
  • RoHS Directive 2011/65/EU;
  • Eco Design Directive 2009/125/EC;

The following relevant harmonised standards or technical specifications have been applied: EN-ISO 12100:2010; EN-IEC 60335-1:2012+A13:2017; EN-IEC 61000-6-1:2019; EN-IEC 61000-63:2007/Al:2011/Cll:2012; EN•IEC 82079-1:2020; ETSI EN 300 220-2 V3.1.1 Commission Regulation (EU) No 1253/2014

Read User Manual Online (PDF format)


Download This Manual (PDF format)

Download this manual  >>

Duco User Manuals

Related Manuals