PIV (Positive Input Ventilation)

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PIV Units Replace The Stale Unhealthy Air in Your Home with Healthy Fresh Air


What is the problem with the air in our homes?

Our modern, sealed homes with double glazing and insulation are more energy-efficient than ever before but they also promote moisture, mould and indoor air pollution.

Pollutants including moisture, cleaning chemicals, mould spores and dust mite faeces can lead to conditions unfit for human habitation.

If you've already tried to cure your mould & condensation issues with more powerful extractor fans, adding sealant all over the place or even just painting over the evidence, you can relax because there is an easier and much more effective solution for you now.

  • Indoor air can be up to 50x more polluted than outdoor air
  • 17 pints of water can be produced indoors, per day, by a family of 4
  • Cooking, bathing and cleaning produce up to 10 litres of moisture per day
  • 90% of our time is spent indoors
  • We breathe 9,000 litres of indoor air per day on average, so creating a healthy living environment is important to our health

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How Does the Unit Prevent This?

Filtered, cleaner, drier air is gently introduced to the home, leading to increased circulation of air around the property.

As air always moves from high-pressure areas to low-pressure areas, cold air is usually pulled in, leaving moisture-heavy stale air in your house. This high moisture content settles onto surfaces in your home which in turn causes all your damp, condensation and mould issues.

Positive pressure ventilation units do exactly what their name says by pushing filtered air into your home creating the pressure which forces the bad stale air out through the existing vents in your home (never cover these up by the way).

Moisture and other pollutants are removed from the air in this way, preventing mould growth.

The unit runs constantly providing consistent high air pressure to ensure that the air in your home is always fresh and free from mould spores, bacteria and other nasties.

Incredible results can be seen just a few weeks after installation of the PIV unit, with reduction or in most cases complete eradication of mould and condensation issues.

The units are available with or without a pre-heater unit that gently warms the filtered air before pushing into your home for additional comfort. These units also include a summer bypass function which automatically switches the heater off during the warmer times of the year. The slightly increased cost of running the heater is offset by your standard home thermostat and also by avoiding the need to open windows during the cold weather to let fresh air in.

By removing the moisture and other air pollutants in this way, mould growth is prevented at the source.

"Mould is a simple plant; if you want to kill it, you must stop watering it!"


PIV Installations are Easier Than Traditional Ventilation Installations

Finding a spot to add a new extractor fan to an already busy home can lead to units being put into an awkward spot spoiling aesthetics or creating noise in an inappropriate area of the home.

Positive Input Ventilation Systems are easily positioned in the loft, mounted on adjustable, vibration-reducing feet. The ducting from the unit connects with a neat grille in the ceiling of your hallway/landing from where it will introduce the clean fresh air.

Read the installation manual to see just how easy this is

  • Extremely cost-effective as running costs for an entire year can be as little as £5
  • Additional F7 filters will also remove pollen and diesel particles. Nox filter models are also available
  • With noise levels as low as 9dB(A), the units can hardly be noticed
  • Perfect maintenance-free choice for landlords and social housing

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Can I Still Have a One if I Don't Have a Loft or Enough Free Loft Space?

Yes, surface mounting units are available and can be mounted in 16 different orientations to suit the home.


Compact, Wall Mounted Units are Available for Properties Without a Loft

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Enhancing Indoor Air Quality with Positive Input Ventilation (PIV) Units

In the quest for energy efficiency, modern homes with enhanced insulation and double-glazing inadvertently create environments conducive to moisture buildup, mould growth, and indoor air pollution. This scenario harbours pollutants like mould spores, dust mite debris, and volatile organic compounds from cleaning agents, posing significant health risks.

Indoor air can be up to 50 times more polluted than outdoor air.

A family of four can produce up to 17 pints of indoor water vapor daily.

Everyday activities like cooking and cleaning add up to 10 Liters of moisture.

We spend 90% of our time indoors, breathing in nearly 9,000 Liters of indoor air daily.

The PIV Solution - How PIV Units Work:

Positive Input Ventilation (PIV) units represent a simple yet effective way to improve the air quality inside your home. These systems work by following a straightforward process, ensuring that the air inside your home is fresh, clean, and healthy. Here’s how they operate:

Drawing in fresh air:

The PIV unit starts by drawing in fresh, outdoor air. This air is typically cooler and contains fewer pollutants than the air inside your home.

Filtering the Air:

As the fresh air enters the PIV unit, it passes through a filter. This filter catches and removes various particles like dust, pollen, and even tiny bugs. The result is cleaner air that's ready to enter your home.

Temperature Adjustment:

In some PIV units, there's an optional pre-heating feature. If the incoming air is too cold, this feature gently warms it up to a more comfortable temperature before it enters your home. This step is especially useful in colder months.

Introducing Air into Your Home:

The cleaned (and possibly warmed) air is then gently pushed into your home. This is usually done through a vent in the ceiling of a central location, like a hallway or landing. The idea is to spread the fresh air evenly throughout your home.

Creating Positive Pressure:

As the fresh air is introduced, it creates a slight increase in air pressure inside your home. Think of it like gently inflating a balloon – the air pushes outwards in all directions.

Expelling Stale Air:

This slight increase in pressure forces the stale, moist air inside your house to move towards and out of the existing air vents, cracks, and other openings. It's a natural process – air always moves from areas of higher pressure to lower pressure.

Continuous Circulation:

The PIV system continuously repeats this process, ensuring that the air inside your home is constantly being refreshed. This prevents the air from becoming stale and reduces the buildup of moisture, which is a common cause of mould.



  • Rapid improvements, often within weeks, including reduced mould and condensation.
  • Cost-effective with low running costs (as little as £5 per year).
  • Additional filtration options for pollen and diesel particles.
  • Ultra-quiet operation (as low as 9dB).

Easy Installation:

  • PIV systems are typically installed in lofts, with discreet ducting and adjustable, vibration-reducing mounts.
  • Hassle-free installation with a straightforward manual guide.
  • Ideal for landlords and social housing due to their maintenance-free nature.

In Simple Terms

Think of a PIV unit like a gentle, constant breeze that flows through your house. This breeze brings in fresh, clean air and pushes out the old, damp air. It's like opening a window to let fresh air in, but without the downsides of cold drafts, noise, or security concerns. The PIV system does this quietly and efficiently, all day, every day, ensuring that the air you breathe inside your home is as fresh as a walk in the park.


5 star review praising PIV units effect on a house with condensation and mould5 star review praising PIV units effect on a house with condensation and mould


Frequently Asked Questions

Can PIV units be installed in homes without a loft?

Yes, with flexible surface-mounted models available.

Are these units noisy?

No, they operate quietly, often imperceptible at a mere 9dB(A).

Is the running cost high?

On the contrary, they are extremely cost-effective with minimal annual expenses.


"Mould is a simple plant; if you want to kill it, you must stop watering it!"


Positive Input Ventilation units are a revolutionary solution to the modern home's air quality challenges, offering an efficient, cost-effective, and quiet way to maintain a healthy living environment.


Buy PIV units from the Fastlec store


Contact and Further Information

For more details, customer support, and technical specifications, please contact our customer service team on 01903 255424 or [email protected].

Need Some Help?



Need some help?
Our phone lines are open Monday - Friday 8 am to 4.30 pm

Call us on: +44 (0)1903 255424



If you wish to get in touch with us via email, you can do so via the email address below.

Enquiries:[email protected]

Returns:[email protected]


Alternatively, you can find the Fastlec store at the address below.

ADR Sussex Ltd (Fastlec)
Units M3-M5, Riverside Ind Est
Littlehampton, West Sussex
BN17 5DF