The Content Of The Article:

Controlled mechanical ventilation is essential to renew the ambient air and evacuate moisture. In double flow version, it saves significant heating costs.

Choose a dual stream VMC

VMC dual streams

A single flow VMC extracts stale air from damp rooms (bathroom, kitchen, WC) and lets in fresh air through the living room and bedrooms. The VMC dual flow, it sucks the outside air from a single point (usually on the roof) to distribute it in the living rooms generally via ducts. Its interest is to recover a large part of the calories present in the evacuated air to warm the renewed air. These flows intersect without mixing, in an exchanger that transfers the calories from one to the other.

VMC dual streams

  • The heat exchanger of a VMC double flow, located in the box, is equipped with a condensate drain, to connect to the home network.
  • Adding a siphon is essential for avoid odors.

A network of ducts

A single-stream VMC has a turbinea double flow model has two. These are usually housed in a box (or central), which also contains the heat exchanger. One of the turbines extracts the stale air, the other breathes new air (or fresh air). This principle remains valid when the turbines are separated from the exchanger, which is then more compact, easier to house and quieter. The ducts that serve each room do not lead directly to the exchanger, which, in most cases, includes only four sewers (125 or 160 mm diameter): external air inlet, exhaust air outlet, air insufflation. fresh air (living rooms), extraction of stale air (kitchen and wet rooms). Thus, the insufflation and extraction ducts join other ducts which are the branches of a linear network, or the insufflation and extraction ducts are connected to distribution boxes (housed in a plenum) comprising themselves four, six or eight stitches of an octopus net.
Disadvantage: as the VMC double flux imposes a double network of ducts, the installation is more complex.

Performance at the key

It is the efficiency - called thermal efficiency or heat recovery rate - of the heat exchanger that largely determines the performance of the installation. Whatever the model, the efficiency decreases as the airflow increases gradually. (92% to 30 m3 / h, 90% to 100 m3 / h, 86% to 200 m3 / h). With gains that allow (according to the manufacturers) to achieve between 20 and 30 \% savings on heating costs. A particularly efficient system in perfectly insulated and airtight housing, as required by the 2012 thermal regulation for new construction.

The flexibility of the bypass

The eight VMCs presented here are equipped with a "bypass" system. Practical, managed manually or automatically, it adapts the VMC to the outside temperature. This function is interesting in the summer: when the outside air is cooler than that of the house, it is redistributed without going through the heat exchanger, so without being heated, thus replacing an air conditioner. VMC dual flow with integrated bypass are obviously more expensive.
The models presented here are hygroadjustable: that is to say, they regulate their flow rate according to the humidity rate of the indoor air generated by the occupation of the housing (the so-called self-adjustable models, cheaper, have, they, a flow constant). This system prevents the appearance of mold. For maximum efficiency, it is advisable to clean the exchanger and filters of the VMC twice a year. For a high-efficiency kit, with a double-flow box, two distribution boxes, four taps, a silencer and a two-speed switch, the price ranges between 500 and more than 2500 euros, excluding installation.

Attic unheated?

VMC model for unheated attic.

Most high flow, dual flow VMCs are designed to fit into a heated volume. But there are models for unheated attics that are also efficient, equipped with an integrated defrost system (Sauter, Paul, Atlantic...).
From 1,000 euros.

Filters are essential for injecting fresh air - rid of pollen and other particles - into the housing, but also to prevent clogging of the heat exchanger during extraction. For insufflation, the filtration is medium, fine or very fine, with type M6 (medium particles) to F7 (fine particle) filters and beyond.
To protect the equipment, the extraction mouth is equipped with coarser filters, from G2 (coarse particles) to M5 (medium particles).

Less noise for VMC news

VMC adjustable with a smartphone

VMC dual flows are today a lot less noisy, and can easily be installed in an inhabited room... So models with box to hang in the attic by a system of cords succeed more and more compact wall models that take place, for example in a kitchen, but also in a small laundry room, a closet...

The connected VMC

VMC and home automation

The VMC does not escape the phenomenon at all connected. A successful model is no longer satisfied with a simple switch, small or high speed and stop. It has an LCD screen on the front or is coupled to a wall control that displays the main functions and modes of operation: manual, automatic, time delay (applied at high speed), bypass... There are often added data such as average room temperature, outdoor temperature, relative humidity, CO2, etc. All these settings and information are accessible from a radio remote control, or even a tablet or smartphone when the control panel is "domotisable".

A VMC controlled via a tablet or a smartphone through a dedicated application (Android or Apple) can work with other connected equipment: water heaters, radiators, shutters, lights... This requires that the VMC uses a protocol (computer language) common (KNX, X2D, MyHome...) to other equipment in the house or a protocol (Modbus type) to use a gateway to others.

Comparison of dual flow VMCs


Click on picture to enlarge

VMC dual stream Aldes

VMC dual stream Aldes

Mark: Aldes
Model: Dee Fly Cube 300 300 micro-watt

  • Price: € 3,093
  • Max. Number of rooms: 7 + 6 bathrooms
  • Max flow rate: 300 m³ / h
  • Filtration: F7
  • Insufflation: G4
  • Extraction
  • Yield (*): 90%
  • Pipes: 4 x Ø 160 mm
  • Overall dimensions (W x H or W x D): 60 x 104 x 58 cm
  • Weight: 42 kg
  • Domotisable: Yes
  • By-pass: Automatic
Strong point:High filtration quality

VMC dual flow Atlantic

VMC dual flow Atlantic

Mark: Atlantic
Model: Duocosy HR HY

  • Price: € 2,424
  • Max. Number of rooms: 7 + 5 bathrooms
  • Max flow rate: 240 m3/ h
  • Filtration: M5
  • Insufflation: M5
  • Extraction
  • Yield (*): 90%
  • Pipes: 4 x Ø 160 mm
  • Overall dimensions (W x H or W x D): 54 x 80 x 42 cm
  • Weight: 30 kg
  • Domotisable: No
  • By-pass: Automatic
Strong point:High flow kitchen function

VMC dual flow Autogyre

VMC dual flow Autogyre

Mark: autogyre
Model: House'air DF HR BC Hygrocomut

  • Price: € 2,011
  • Max. Number of rooms: 7 + 6 bathrooms
  • Max flow rate: 285 m3/ h
  • Filtration: M5
  • Ventilation: G4
  • Extraction
  • Yield (*): 88%
  • Pipes: 4 x Ø 125 mm
  • Overall dimensions (W x H or W x D): 67 x 37 x 59 cm (exchanger block)
  • Weight: 11 kg
  • Domotisable: No
  • By-pass: Automatic
Strong point: Compact housing (weight and small footprint)

VMC double flow HBH (at Castorama)

VMC double flow HBH (at Castorama)

Mark: HBH (at Castorama)
Model: Model HV

  • Price: € 799
  • Max. Number of rooms: 4 + 3 bathrooms
  • Max flow rate: 176 m3/ h
  • Filtration: antibacterial filter
  • Insufflation: antibacterial filter
  • Extraction
  • Yield (*): 86.1%
  • Pipes: 3 x Ø 80 mm; 1 x Ø 125 mm
  • Overall dimensions (W x H or W x D): 53 x 44 x 32.5 cm
  • Weight: 23.2 kg
  • Domotisable: No
  • By-pass: Manual
Strong point: the price

VMC double flow Sauter

VMC double flow Sauter

Mark: Jump
Model: VMC Double Flow HR +

  • Price: € 1,699
  • Max. Number of rooms: 7 + 7 bathrooms
  • Max flow rate: 270 m³ / h
  • Filtration: M5
  • Insufflation: M5
  • Extraction
  • Yield (*): 89%
  • Pipes: 4 x Ø 160 mm
  • Overall dimensions (W x H or W x D): 80 x 53.5 x 42 cm
  • Weight: 30 kg
  • Domotisable: No
  • By-pass: Automatic
Strong point: Price / surface ratio

VMC dual flow S & P Unelvent

VMC dual flow S & P Unelvent

Mark: S & P Unelvent
Model: Domeo 210 HY

  • Price: € 2,274
  • Max. Number of rooms: 5 + 4 bathrooms
  • Max flow rate: 210 m3/ h
  • Filtration: M5 (F7 optional)
  • Insufflation: G4
  • Extraction
  • Yield (*): 91%
  • Pipes: 4 x Ø 125 mm
  • Overall dimensions (W x H or W x D): 60 x 81 x 32 cm
  • Weight: 15 kg
  • Domotisable: Yes
  • By-pass: Automatic
Strong point: Very low consumption motor

VMC double flow Vortice

VMC double flow Vortice

Mark: Vortice
Model: Vort Prometeo HR 400 Plus

  • Price: € 3,025
  • Max. Number of rooms: 7 + 5 bathrooms
  • Max flow rate: 375 m3/ h
  • Filtration: F5 (F7 optional)
  • Insufflation: F5 (F7 optional)
  • Extraction
  • Yield (*): 92%
  • Pipes: 4 x Ø 150 mm
  • Overall dimensions (W x H or W x D): 84 x 93.5 x 50 cm
  • Weight: 25 kg
  • Domotisable: Yes
  • By-pass: Automatic
Strong point: Ultra-quiet

VMC double stream Zehnder

VMC double stream Zehnder

Mark: Zehnder
Model: ComfoAir Q 350

  • Price: € 2,748
  • Max. Number of rooms: 5 + 7 bathrooms
  • Max flow rate: 350 m3/ h
  • Filtration: F7
  • Insufflation: G4
  • Extraction
  • Yield (*): 97%
  • Pipes: 4 x Ø 160 mm
  • Overall dimensions (W x H or W x D): 72 x 85 x 57 cm
  • Weight: 50 kg
  • Domotisable: Yes
  • By-pass: Automatic
Strong point: Very high efficiency

(*) According to the requirements of UNICLIMA Performance Display Charter, this value is obtained under standard test conditions. It corresponds to a flow of 120 m3/ h, representative of the permanent ventilation rate of an average dwelling type T4.


Video Instruction: