Ventilation systems from STIEBEL ELTRON

Advanced ventilation systems – more than just a change of air

Advanced ventilation systems ensure regular air changes without wasting valuable energy. Subject to model, they can even provide DHW and central heating.

Why is ventilation so important?

For practical thermal insulation purposes, nowadays, modern homes are so airtight that virtually no energy is lost. Low energy houses in particular have an airtight building envelope primarily to prevent heat losses. This also prevents any natural air change and makes mechanical ventilation essential.

However, ventilation is also an issue in older homes. As a result of subsequent thermal insulation measures, there is often no longer an adequate supply of outdoor air through gaps and other previously air permeable spots. This creates a conflict of interest between practical thermal insulation and the need for fresh air, which can be resolved with mechanical ventilation systems.

The increasing impermeability of new buildings and modernised residential dwellings in particular, calls for a continuous air change, for example, in order to avoid the growth of fungal mould and damage to the building. However, ventilation via windows is not very practicable as the sole means of ventilation. To ensure an energy efficient and hygienic minimum air change, ventilation via windows would have to occur four to six times a day for approx. 5 minutes each time. Heating would have to be turned off and windows fully open, making this virtually impossible.

Mechanical ventilation systems reliably safeguard the necessary supply of fresh air, as well as energy efficient central heating and DHW.

The various ventilation systems

Decentralised ventilation: accurate and energy efficient

In the case of decentralised mechanical ventilation, a distinction is drawn between systems with and without heat recovery: decentralised systems with heat recovery have a single unit installed in the external wall of every room to be ventilated. For this, there are systems with two fans and heat recovery via a countercurrent heat exchanger for example. When choosing suitable decentralised appliances, it is also important to look for the lowest possible sound emissions and at ease of cleaning and maintenance. It should be possible to control the individual fans so that the air flow rate can be matched to demand.

A decentralised ventilation solution is the number one choice, particularly for modernisation projects or specific moisture problems. The installation work required is usually minimal. Individual units work independently of one another to extract air from rooms where humidity is critical, such as bathrooms and kitchens. In conjunction with a second appliance, they ensure good ventilation throughout the living space. Separate sensors control the appliances subject to the indoor air humidity level.

Decentralised ventilation solutions

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Central ventilation: for a fresh ambience throughout

With central ventilation units, a distinction is drawn between extract air systems and supply/extract air systems. The simplest and most cost effective system for central mechanical ventilation is an extract air system. Stale air is extracted via ductwork from the extract air areas such as the kitchen, bathroom and toilet. At the same time, the resulting negative pressure causes fresh air to be drawn through outdoor air apertures directly into the supply air areas (living room, play room, bedrooms). The air volume extracted from the extract air areas is determined by the fan capacity. Occupants can match the air flow rate to their demand via a simple step switch. With a small heat pump, the extract air can be utilised for DHW heating and, if required, central heating. Using extract air at relatively high temperatures as a heat source ensures excellent levels of efficiency.

The ventilation ducts required for this can be let into walls, concrete or suspended ceilings, the floor, or placed under a screed layer – even in the open. This option is therefore particularly appropriate for new build and for comprehensive modernisation projects. Its major advantage lies in the uniform fresh air quality it delivers throughout the entire building. The energy recovered from the extract air can be used to heat the supply air.

Unlike an extract air system, a supply/extract air system draws the outdoor air from a central point and distributes it by means of pipework throughout the supply air areas. Heat is recovered in a countercurrent heat exchanger, transferring up to around 90 % of the latent heat in the extract air to the supply air. The outdoor air is filtered to prevent contamination of the unit and ductwork, and to protect allergy sufferers against the effects of dust and pollen. Various filter qualities are available. Central supply/extract air systems ensure excellent levels of comfort in the home.

Central ventilation solutions

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