Single-Room MVHR Units: A Practical Guide

Single-Room MVHR Units: A Practical Guide

Mechanical Ventilation with Heat Recovery is commonly associated with whole-house systems that use a central MVHR unit and a network of ductwork. However, installing ductwork throughout an existing property is not always practical.

A single-room MVHR unit provides a more localised solution. Installed through an external wall, it ventilates an individual room while recovering some of the heat from the outgoing air. This can make single-room heat recovery particularly useful for renovations, apartments and spaces where a full ducted system would be difficult to install.

Quiet-Vent supplies a range of single-room MVHR units for merchants, installers and ventilation specialists, including compact reversible units and balanced wall-mounted heat exchangers.

What is a single-room MVHR unit?

A single-room MVHR unit is a compact ventilation system designed to serve one room or a defined area rather than an entire property.

The unit is normally mounted on an external wall and connected directly to the outside through one or more short wall ducts. It removes stale indoor air, introduces fresh outdoor air and transfers heat between the two airstreams.

Unlike a standard extractor fan, which only removes air, a single-room heat recovery unit provides a controlled route for both outgoing and incoming air.

Depending on the model, it may operate using:

• Simultaneous supply and extract airflow.
• Alternating supply and extract cycles.
• A heat exchanger or ceramic heat storage core.
• Manual, remote, humidity or app-based controls.
• Individual or synchronised multi-unit operation.

How does single-room heat recovery work?

There are two main operating methods used by single-room MVHR units.

Alternating airflow units

Reversible units use one fan and a heat-retaining ceramic core.

During the extract cycle, warm stale air passes through the unit and transfers heat to the ceramic core. The fan then reverses, drawing fresh outdoor air through the warmed core and into the room.

This process repeats at regular intervals. The BSK Zephyr and Zephyr Mini, for example, alternate between extract and supply operation every 70 seconds and can be connected with other compatible units using Wi-Fi controls.

Alternating units can be installed individually, but paired or synchronised operation may provide better balanced ventilation across the space. The exact arrangement should follow the product instructions and ventilation design.

Simultaneous supply and extract units

Other single-room systems have separate paths for incoming and outgoing air, allowing them to supply fresh air and extract stale air at the same time.

The Mitsubishi Electric Lossnay VL-50 and VL-80 use this type of balanced operation. Their heat exchanger transfers energy from the outgoing indoor air to the incoming outdoor air without directly mixing the two airstreams.

Benefits of single-room MVHR units

Suitable for retrofit projects

One of the main benefits of a decentralised MVHR unit is that it does not require ductwork to be routed throughout the property.

This can make it suitable for existing homes, apartments and individual rooms where ceilings, floors and wall finishes have already been completed.

Installation will generally require:

• A suitable external wall.
• One or more correctly sized wall openings.
• An electrical supply or control connection.
• An internal unit or grille.
• A weather-resistant external terminal.

The specific requirements depend on the selected model.

Recovers heat from outgoing air

A basic extractor fan removes warm indoor air directly to the outside. The replacement air then enters through background ventilators, open windows or gaps in the building fabric.

A single-room MVHR unit instead transfers heat from the outgoing air to the incoming fresh air. This helps reduce unnecessary ventilation heat loss while still providing controlled air replacement.

Heat recovery efficiency varies between products, airflow settings and test conditions. The published performance information for the individual unit should therefore be checked rather than assuming every model performs identically.

Provides targeted ventilation

Single-room heat recovery can be useful where one particular space requires additional ventilation.

Typical applications can include:

• Bedrooms.
• Living rooms.
• Home offices.
• Apartments.
• Garden rooms.
• Small commercial spaces.
• Rooms affected by stale air or limited natural ventilation.

Suitability for bathrooms, utility rooms and other areas with higher moisture levels should be checked against the product specification, electrical zoning requirements and the ventilation strategy for the building

Reduces the need for extensive ductwork

A whole-house MVHR system normally requires separate supply and extract duct routes connecting the central unit to multiple rooms.

A single-room unit only needs to pass through the external wall that it serves. This reduces disruption and can make heat recovery ventilation possible where there is no suitable route for a central ductwork system.

Flexible control options

Control options vary across the range and can include:

• Pull-cord operation.
• Wall switches.
• Handheld remote controls.
• Humidity sensing.
• Adjustable fan speeds.
• Night-time settings.
• App and Wi-Fi control.
• Communication between multiple units.

For example, the BSK Zephyr range includes remote and Wi-Fi control options, while the Mitsubishi Lossnay VL-50 uses pull-cord control and the VL-80 is designed for connection to a wall switch.

Single-room MVHR compared with an extractor fan

An extractor fan and a single-room MVHR unit are not the same type of ventilation system.

Feature	Extractor fan	Single-room MVHR
Removes stale air	Yes	Yes
Mechanically supplies fresh air	No	Yes
Recovers heat	No	Yes
Requires a wall opening	Usually	Yes
Filtration	Usually limited or none	Product-dependent filters
Suitable for continuous operation	Model-dependent	Commonly designed for continuous use
Installation cost	Generally lower	Generally higher
Controls	Basic timer, switch or sensor	Speed, remote, humidity or smart control options

An extractor fan may remain the appropriate choice for a bathroom or utility room where direct high-rate extraction is required.

A single-room MVHR unit is more suitable where controlled air replacement and heat recovery are important. The required ventilation rate and intended room use should determine the product rather than heat recovery alone.

Single-room MVHR compared with whole-house MVHR

Single-room MVHR and whole-house MVHR both recover heat, but they serve different project requirements.

Single-room MVHR may be suitable when:

• Only one or two rooms need mechanical ventilation.
• The property is already finished.
• There is no practical route for a complete duct network.
• A localised retrofit solution is required.
• Individual room control is preferred.

Whole-house MVHR may be suitable when:

• The entire property requires balanced ventilation.
• The project is a new build or substantial renovation.
• Ductwork can be planned before ceilings and walls are closed.
• Supply ventilation is needed in several habitable rooms.
• Extract ventilation is needed from multiple wet rooms.
• A coordinated whole-building ventilation strategy is required.

A collection of single-room units should not automatically be treated as a direct replacement for a designed whole-house MVHR system. The combined airflow, room distribution, transfer paths and extract requirements must still satisfy the ventilation requirements for the property.

Quiet-Vent also supplies centralised whole-house MVHR units and complete ducting components for projects requiring ventilation across the full building.

Choosing a single-room MVHR unit

Required airflow

The airflow should be appropriate for the room size, occupancy and intended use.

A small bedroom may require a different unit or speed setting from a large open-plan living space. Always compare the airflow at each operating speed rather than looking only at the maximum figure.

Type of heat recovery

Check whether the product uses:

• An alternating ceramic heat storage core.
• A simultaneous plate or membrane heat exchanger.
• Sensible heat recovery.
• Sensible and latent heat recovery.

The operating method affects how the unit is installed, controlled and combined with other ventilation equipment.

Wall construction and thickness

The unit must be compatible with the wall depth and construction.

Check:

• Required core-drilled hole diameter.
• Minimum and maximum wall thickness.
• Extension components.
• External hood dimensions.
• Required installation angle or fall.
• Clearances around the internal and external sections.

Sound levels

Sound performance is particularly important in bedrooms, home offices and living rooms.

Compare the published sound information at the airflow setting that is likely to be used most often. A low sound figure at minimum speed does not necessarily represent the noise level at the airflow required for the project.

Controls and synchronisation

For a simple installation, a pull cord, remote or wall switch may be sufficient.

For several rooms, it may be more useful to select units that can communicate with one another. Compatible reversible units can be configured so that one unit supplies air while another extracts, before their airflow directions change.

Filtration and maintenance

Single-room units normally include filters that require periodic inspection and cleaning or replacement.

The installation position should allow the internal cover, filters and heat exchanger core to be accessed without damaging finishes or moving furniture.

External appearance

The outside terminal should be considered before installation, particularly on prominent elevations.

Available options may include:

• Standard white external grilles.
• Coloured wall hoods.
• Stainless-steel terminals.
• Narrow wall cowls.
• Weather-resistant external covers.

Technical and design support from Quiet-Vent

Choosing between a single-room unit and a centralised MVHR system is not always straightforward. The answer depends on the number of rooms, required airflow, building layout and the level of renovation involved.

Quiet-Vent provides technical advice on product selection, system layout and component compatibility. For larger residential or commercial projects, our design team can review the plans and help develop an appropriate MVHR unit and ductwork specification.

This support also helps merchants respond to customer enquiries with clearer product recommendations rather than selecting equipment using room size alone.

Explore Quiet-Vent’s single-room MVHR units, or submit a ventilation design request for support with a complete system.