We have discussed in the past of how passive vents alone do not provide effective cross-flow ventilation. Pest management companies who utilise Envirofan systems can take the guess work out of sub floor ventilation.
This is done by using the Envirofan system to ingress the outside air into the subfloor area. When connected to solar power and in times of wet weather these do not operate. In fair weather or full sun these continue to pump dry air into the sub floor area.
The image to the right shows how the Envirofan brick size unit can be used to modify an 18 x 6 passive vent to ingress supply air into the subfloor area preferably by solar power or by the extraction process which is the most common practice which would expel the humidity from the sub-floor area at 2750 litres/minute whereby the same amount of air would be drawn into the sub floor area through other 18 x 6 passive vents. Which is the ideal recipe to achieve cross flow ventilation.
Envirofan has the right combination in effective sub floor ventilation. The sub floor systems moves high volumes of air over a longer period of time. However two Envirofan quad fan system can equate in air volume to what a mid sized 240v in-line fan system will do and with only one tenth of the power usage. An article put out by a restoration company which says otherwise describing 12v low voltage ventilation fans, should not be taken as fact.
Consideration should be given that larger in-line fans used in sub floor ventilation move high volumes of air in a short period of time, in the case of reactive clay soils this can create upheaval in the foundations of a dwelling by excessive drying out.
Envirofan was produced for the benefit of the pest management industry. With simple installation methods to benefit themselves and their clients. Pest management companies are not electricians to install a power outlet under the building. Nor are they experts in balancing each ducting branch inlet with equal airflow rates by using an anemometer, which is associated with in-line fan with ducting installations. Simplicity is the key with Envirofan low voltage systems.