PIV & dMEV ventilation installation

Positive Input Ventilation, or PIV, introduces filtered air into a dwelling to help dilute moisture-laden air. Loft-mounted and wall-mounted systems are available, with suitability depending on the building and the manufacturer's requirements.

A PIV system needs suitable airflow paths through the home. The layout, existing ventilation and installation position matter just as much as choosing a unit.

Decentralised Mechanical Extract Ventilation, or dMEV, uses individual fans to continuously extract air from rooms such as kitchens and bathrooms. Fans typically run at a low background rate and can boost extraction when required, depending on their controls.

The duct route, external outlet, replacement airflow and noise requirements all need consideration. Correct installation and commissioning help the system deliver the intended airflow rather than simply replacing an existing fan like for like.

Condensation on windows, persistent moisture after bathing and poorly ventilated rooms can indicate that airflow needs attention. Tell us which rooms are affected, whether you have existing extract fans and whether there is accessible loft space.

Ventilation can help manage moisture, but it is not a universal cure for damp or mould. Leaks, penetrating damp and building defects need their own investigation. PIV and dMEV do different jobs, so the best approach depends on the property rather than a single system suiting every home.