What is the difference between a PIV and Extract Unit?

What is the difference between a PIV and Extract Unit?

Positive Input Ventilation (PIV) and Extract units work in complimentary ways to reduce the risk of condensation and improve the air quality within properties.  The most rudimentary way to explain the differences between a PIV unit is to say that a PIV unit blows air whilst an extract unit sucks it up!

A PIV unit is designed to dilute the air within the home to reduce the relative humidity (air moisture) to a level where condensation should be significantly reduced or stop. They tend to be positioned in a landing, hallway or other central point in the property so that their effect can be felt throughout the property. As warm moisture laden air rises, the PIV will mix with this warm moisture laden air, dilute it, and through this dilution will push the excess moisture out of the natural gaps and even through the existing extract ducts. PIV units also push ‘clean’ filtered air into the property, whereas extract units will remove stale and contaminated air from the property.

An extract unit is designed to remove ‘point of source’ air moisture from the main water forming areas such as the kitchen or bathroom before it spreads throughout the property and causes or contributes towards a condensation issue.

Why we may suggest a PIV unit and Extract units?

Extracts are to remove ‘point of source’ moisture in the key moisture forming locations such as kitchens and bathrooms and the PIV unit deals with the moisture that escapes these areas and that is generated by the tenants/homeowners through breathing, cooking, cleaning  ironing, drying and bringing rain soaked clothing and pets inside. Where PIV and extract units are required, they provide a ventilation system that removes excess moisture and dilutes any ambient moisture.