What is a MVHR system? Ventomaxx

Controlled domestic ventilation (CDV system) with heat recovery is now standard in modern buildings. It ensures a continuous fresh air supply without negatively affecting the building’s energy balance. However, despite its widespread use, there are many technical details that planners and installers must understand in order to efficiently plan, install and maintain these systems.

In this article, we explain everything you need to know about controlled domestic ventilation systems – from key components and correct installation to common mistakes and how to avoid them.

What is a Controlled Domestic Ventilation System?

A controlled domestic ventilation system, also known as a comfort ventilation system with heat recovery (HRV), is used in buildings to ensure controlled ventilation with optimal energy efficiency. This system removes stale indoor air while simultaneously supplying fresh air, recovering a large portion of the heat from the exhaust air in the process. This not only reduces energy consumption but also improves the indoor climate.

Ventilation systems with heat recovery (HRV) are increasingly used in both new builds and refurbishment projects. They ensure a continuous fresh air supply while removing stale, humid air. The key feature is heat recovery: as exhaust air is discharged outside, it transfers its heat to the incoming supply air, preventing valuable heating energy from being lost.

Compared to conventional ventilation systems, systems with heat recovery (HRV) offer numerous advantages, including lower energy costs, improved living comfort, better indoor air quality and enhanced sustainability.

Proper planning and installation are essential to ensure optimal performance and efficiency. Professional installation and regular maintenance are crucial to maintaining the system’s lifespan and performance.

Components and How a Ventilation System with Heat Recovery Works

A ventilation system with heat recovery consists of several key components working together to ensure effective ventilation:

Ventilation units: These are the core of the system and enable the air exchange between indoor spaces and the outside environment.
Heat exchanger: Transfers heat from the exhaust air to the supply air, enabling heat recovery.
Air ducts: Transport air between the ventilation units and the individual rooms. For decentralised systems, no complex duct installation is required – a core drilling through the exterior wall and a power connection are sufficient for quick commissioning.
Filters: Clean the supply air from dust, pollen and other pollutants before it enters the room.

Central systems use a single unit to distribute air throughout the entire building, while decentralised ventilation systems use multiple units in different rooms. Decentralised systems offer flexible installation and are particularly suitable for retrofitting or customised solutions.

The core element of the system is the heat exchanger, which transfers heat from the exhaust air to the incoming fresh air without mixing the two airflows. This allows the supply air to be preheated or precooled depending on the season, significantly reducing heating and cooling demand and saving energy.

Controlled air exchange removes pollutants, excess humidity and CO₂ from indoor air, ensuring consistently high air quality and preventing mould growth. This supports a healthy indoor climate and enhances occupant comfort. At the same time, the system ensures an even distribution of fresh air and eliminates unpleasant odours.

Modern systems also offer high flexibility and user-friendliness, enabling demand-based control of energy consumption, reducing operating costs and conserving resources in the long term.

Planning a Controlled Domestic Ventilation System

Airflows

Accurate airflow planning is a key step in installing a ventilation system with heat recovery. Before installation, the required airflow must be calculated for each room. Rooms such as kitchens and bathrooms typically require higher airflow rates, while bedrooms and living rooms may need lower air exchange rates.

The air change rate indicates how often the air in a room should be completely replaced within one hour. Correct calculation is essential for optimal system performance.

Airflow must be precisely matched to room size and comfort requirements. Insufficient airflow can lead to poor indoor climate, while excessive airflow increases energy consumption unnecessarily. The system must be correctly sized according to building type and usage.

Sound Insulation and Airflow Optimisation

Noise generated by airflow and ventilation units can negatively impact comfort. Therefore, effective sound insulation is essential. Ensure that all ventilation units and air ducts are properly insulated to minimise noise.

Air ducts should be installed in a way that allows smooth and efficient airflow throughout the system. Tight bends, undersized ducts or blockages can restrict airflow and increase energy consumption.

Heat Exchanger

As mentioned earlier, the heat exchanger plays a central role in every system. It transfers heat from exhaust air to supply air without mixing the airflows. The selection depends on the building’s heating requirements: poorly insulated buildings require high-performance heat exchangers, while smaller units may be sufficient in well-insulated buildings.

Common Installation Mistakes – and How to Avoid Them

Incorrect installation can significantly reduce system performance. Common mistakes include:

Insufficient planning: Incorrect system sizing leads to poor air exchange or unnecessary energy consumption
Incorrect positioning of air openings: Causes uneven air distribution and reduced comfort
Improper duct installation (central systems): Leaks reduce efficiency and lead to air loss
Lack of maintenance: Results in higher energy consumption, poor air quality and system failures
Incorrect ventilation settings: Too high leads to draughts, too low reduces air exchange

Decentralised systems offer a key advantage: no complex air duct installation is required.

To avoid these issues, ensure professional planning, high-quality materials, proper installation and regular maintenance.

Why Ventomaxx is the Right Choice for Your Ventilation System

When selecting a ventilation system, reliability, efficiency and durability are essential. With over 20 years of experience in developing and manufacturing ventilation solutions, Ventomaxx offers customised systems tailored to your needs.

Ventomaxx ventilation systems with heat recovery (HRV) stand out for their high quality and flexibility. With active decentralised ventilation systems, including heat recovery and highly flexible sound-insulated solutions, Ventomaxx provides products suited to a wide range of applications.

Thanks to their modular design, Ventomaxx systems are ideal for residential buildings, hotels, kindergartens, schools, commercial buildings and single-family homes. They ensure optimal air circulation and excellent sound insulation, contributing to a healthy indoor climate.

Ventomaxx also places great emphasis on customer support. Our experienced team provides expert advice and tailored solutions to ensure efficient and time-saving installation.

By choosing Ventomaxx, you benefit from high-quality, durable materials and regional supply chains, ensuring short delivery routes and reliable service.

What is a MVHR system?