MORI WMF Sub-Floor Mechanical Ventilation Fan

MORI WMF is a weatherproof, multifunctional fan unit for use when an easy accessed, externally mountable, continuously running ventilation fan is required e.g. to provide sub-floor ventilation.

Many sub-floor spaces have insufficient natural ventilation with the only option to provide some form of mechanical Ventilation to the space. The MORI WMF was specifically designed for such applications.
The combination of wide airflows and various control modes provides the sub-floor ventilation system designer with much choice and flexibility.

The integral controls provided as standard allow for the fan to be set at installation stage to operate at 3 different speeds/airflows and, at each speed/airflow, to operate in supply mode, extract mode or alternate flow mode with the fan automatically switching itself between supply and extract modes every 70 seconds.

When set up to provide automatic alternate flow, the fan can be set to start on either supply or extract mode when connected to the mains power. This allows multiple units to be “synchronised” with each other if required to ensure as one or more units supply air, the other unit or units extract air, with operating modes of each fan alternating every 70 seconds.

Unique weatherproof design allowing the fan to be mounted outside making installation and maintenance easier than with sub-floor mounted fans. Discreet unit appearance available in 5 different colours to blend in with the dwelling.

Low energy fan/motor assembly with typical electrical running cost of £2-5 per year for continuous operation. Ultra-quiet operation on all operating modes.

Multi-functional controls as standard set up by installer selecting from:

• Speed 1, Extract @ 4l/s or Supply @ 4l/s
• Speed 2, Extract @ 7l/s or Supply @ 6l/s
• Speed 3, Extract @ 12l/s or Supply @ 10l/s
• Extract mode only
• Supply mode only
• Alternate flow mode with the fan switching itself automatically between supply and extract mode approximately every 70 second
• Synchronisation of fans when in alternate flow mode (See diagrams on the data sheet)

You will struggle to find any advice anywhere on mechanical ventilation rates for sub-floor spaces for humidity control. We know this is something that the sub-floor insulation industry is looking at but so far there is no official recognised guidance.

We believe an air change rate of about 1 air change per hour feels about right, but this is in no way backed up by any technical documentation and is not Alliance Remedial Supplies giving any design advice.

For example: A 40m² subfloor with a height of 0.6m (24m³) will require and extraction rate of 6.6l/s to achieve and 1 air change per hour. This requires the WMF to be set to speed setting 1, extract rate of 7l/s.

Units available with polyester powder coated matt / 30% gloss finish front cover/grille in 4 different colours as follows: