1. What is Positive Input Ventilation (PIV)?

PIV is a whole-house ventilation system that continuously supplies filtered fresh air into a building from a central unit (typically installed in lofts or cupboards). It creates positive pressure to force stale, humid air out through natural leakage points, reducing condensation and dampness.

2. How does PIV address damp and mould?

By introducing dry, filtered outdoor air, PIV lowers indoor humidity levels that cause condensation. This disrupts the environment mould needs to grow, effectively tackling damp walls, window condensation, and musty odours.

3. Can PIV cause cold spots or drafts?

Yes, some users report cold corridors near ceiling diffusers, especially in homes with high ceilings (e.g., Victorian properties). This occurs when:

• Incoming air isn’t adequately tempered before dispersion
• Diffusers are poorly positioned, creating localized cold zones
• Air descends rapidly in large vertical spaces 

4. Does PIV work well in multi-storey homes?

Performance varies. Upper floors often receive excessive airflow while ground floors remain under-ventilated due to:

• Natural thermal stacking pulling air upward
• Insufficient pressure to overcome lower-level resistance
• Lack of zonal controls for targeted airflow 

5. Is PIV energy-efficient?

Most units consume only 5-21W (similar to a LED bulb), but winter operation may increase heating costs as incoming cold air requires warming . Models with heaters temper air but raise electricity usage.

6. How noisy are PIV systems?

Modern units operate at 19-30 dB (quieter than a whisper). Noise concerns typically arise from:

• Incorrect installation near living spaces
• High-speed settings during extreme humidity
• Vibration transfer through ceiling structures 

7. Can I install PIV with closed interior doors?

Closed doors significantly reduce effectiveness. PIV relies on air movement through open pathways; sealed rooms experience minimal airflow exchange, leading to uneven ventilation and persistent damp spots.