How to maintain a MEV?

Regular maintenance for better quality

From a regulatory point of view, there is no text indicating the necessary actions or their frequency in the maintenance of a single flow controlled Mechanical Extract Ventilation system, or MEV. Nevertheless, the French decree of 22 October 1969 – on the ventilation of dwellings – implies that “the capacity to ventilate homes must be general and permanent at least during the period when the temperature obliges windows to be kept closed and that it must be possible for air to circulate in general from the dry rooms to the wet rooms”. Without indicating that maintenance is necessary, the decree regulates the basic rules of ventilation within a dwelling.

What are the key steps in maintaining an Mechanical Extract Ventilation system?

For some ventilation systems, such as MEV for buildings with shared occupation, maintenance and servicing of the system is usually mandatory. To determine the maintenance and servicing actions to be performed for an MEV, it is necessary to make a list of the various ventilation system components.

• For the maintenance of the air inlets, annual cleaning is sufficient to ensure proper functioning. In general, maintenance can be done with a damp cloth. Under no circumstances should a humidity-controlled air intake be rinsed under water. This would affect the functioning of the humidity-sensitive fabric and would no longer guarantee renewed air flows.
  Take care never to block the air inlets, otherwise it will not be possible for the home to receive fresh air. The air inlets must also always remain accessible.
• The same applies to the maintenance and accessibility of the exhaust units. It should be noted that some exhaust units may operate with a power supply which can be provided by either batteries or a power supply board. In the case where the power supply is provided by batteries a check of the operating state of the exhaust unit must be done annually in order to check the correct autonomy of the battery. However, in the case where the power supply is provided by a power supply board there is no need for any electrical check. Indeed, the advantage of the power supply board over the batteries is that it is linked to the dwelling power supply and thus allows to get free from the limited autonomy of the batteries. For the specific power supply board that is directly linked the dwelling power supply it is necessary to cut the exhaust unit power supply even before removing the front face for maintenance. Those prescriptions are explicitly mentioned in the installation notice of the power supply in question.
• Air transit passages, usually located under the doors between two rooms, must be large enough to ensure proper air circulation between rooms. For example, a door undercut must be at least 1 cm high over the entire width of the door.
• It is important to check the power system of an MEV as it is to verify the air inlets or exhaust units. If an individual Mechanical Extract Ventilation system is installed, there are solutions for cleaning the duct. This action should be done every 5 years. For communal networks, network maintenance should be carried out at least every 5 years and preferably every 2 years.
• Finally, with regard to the ventilation unit, the central part of the ventilation system, it is essential to ensure that the following maintenance points are followed:

1. Verification of the wear of the connecting parts between the system and the connection sleeves of the fan. If these parts appear worn, it is necessary to change them for identical parts.
2. The turbine of the MEV box must be cleaned, preferably every year, and at least every two years. Some Aereco fans have filters that protect the turbine. It is therefore necessary to clean them every year and to change them every two years. For other fans, some have a patented system for removing the turbine for cleaning with hot water. Once dry, it can easily be put back into place.

For communal Mechanical Extract Ventilation units, some are equipped with a belt. This must be replaced if worn.

• The final item to inspect is the discharge on the roof. It is necessary to visually check that it is not obstructed and is in good condition.