Positive Input Ventilation (PIV)

Positive Input Ventilation — or PIV — is one of the most effective long-term ways to reduce condensation, damp, and mould in UK homes. It’s been around since the 1970s, used in over a million properties, and is trusted by landlords, housing associations and homeowners alike. Unlike short-term fixes, PIV tackles the cause of condensation by improving the overall air quality inside your home.

How PIV Works

A PIV unit is usually installed in the loft. It gently introduces a constant supply of fresh, filtered air into the home. This isn’t a blast of cold air — it’s a slow, steady airflow that:

• Dilutes moist indoor air

• Pushes out stale, humid air

• Reduces condensation on cold walls and windows

• Lowers humidity so mould cannot grow

As the fresh air flows through the home, the moisture level drops — and with it, the damp and mould problems. It’s a very simple principle, and that’s exactly why it works.

Why PIV Is So Effective

Homeowners choose PIV because it solves multiple problems at once:

• ✓ Stops Condensation No more wet windows in the morning or moisture on the walls.

• ✓ Prevents Mould Lower humidity means mould simply cannot survive.

• ✓ Warmer, Drier Rooms Dry air is easier to heat, so homes often feel warmer and heat up quicker.

• ✓ Cleaner Air The filters remove pollen and pollutants — great for asthma and allergy sufferers.

• ✓ Quiet and Low Running Cost Most units cost just pennies per day to run.

• ✓ Maintenance is minimal A filter change every few years is normally all that’s needed.

Which PIV System Do You Need?

It depends on your property type:

• Houses with Lofts A loft-mounted system gently feeds filtered air down into the hallway.

• Flats and Apartments A “Flatmaster-type” system brings fresh air in from outside at low level.

Both systems deliver the same result: fresh, filtered air that reduces condensation.

Why PIV Works Better Than Dehumidifiers

Dehumidifiers only treat one room. PIV treats the whole house. Dehumidifiers cost more to run, they fill up, they need emptying, and they only deal with symptoms. PIV deals with the cause by improving air quality.

When We Recommend PIV

We fit PIV systems when:

• Humidity is consistently high

• Windows stream with water each morning

• Bedrooms feel damp or musty

• Cold walls create condensation

• Mould keeps returning

• There’s poor natural ventilation

• Subfloor issues are also present (we often combine PIV with underfloor ventilation)

PIV isn’t a magic gadget — it’s a proven airflow strategy that has worked for decades.

Professional Installation by Condentrol

We survey your home first to make sure a PIV system is the right solution — we never install one unless it will work.

Our installation includes:

• Full humidity assessment

• Correct placement for maximum benefit

• Advice on managing moisture

• Setup and commissioning to suit your home

• Future support if needed