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How PIV Systems Stop Condensation

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How PIV Systems Stop Condensation

By Ruth MacEachern

Product Manager

Feb 09, 2024

During the winter months, it is more common to wake up and see condensation forming on the inside of your windows. If your home is prone to high levels of humidity, condensation can cause serious problems including damp and mould.

What is condensation and what problems can it cause

Condensation is formed when warm and humid air meets a cold surface such as a window or exterior wall. As the temperature of the air drops, the amount of moisture that it can carry is reduced, and this water vapour is released onto the surface. On a non-porous surface such as glass, the condensation will form as droplets that can be wiped away, however on other surfaces such as wood or normally painted walls, the condensation can soak through into the underlying material.

As the moisture is absorbed by plaster or wood, it will form patches of damp that can worsen over time. These damp patches create the perfect environment for mould to grow which can be bad for the health of your household. Many people have allergic reactions to the spores from mould and in people with weaker immune systems, mould can lead to serious health problems.

How to reduce condensation

Condensation results from high levels of moisture in the air. This moisture comes from a variety of household activities including cooking, bathing, and even breathing. Reducing the humidity levels in your home will help to reduce the amount of condensation. Simple changes such as ensuring that you use pan lids when cooking on the hob and avoid drying clothes on radiators can help, but improving ventilation in your property is the only way to stop condensation for good.

Ventilation and condensation

A range of different ventilation systems are available. Simple extractor fans should be installed in your bathroom and kitchen to remove water vapour as it is produced, however if you have discovered condensation in rooms away from the sources of water vapour, a whole house ventilation system may be more appropriate.

What is Positive Input Ventilation (PIV)?

Positive Input Ventilation (PIV) is a smart solution designed to tackle ventilation problems in existing homes. PIV creates a healthier indoor environment by pumping and circulating fresh, filtered air into the house while simultaneously forcing stale air out through gaps and cracks in the building fabric.


How PIV systems work

Installation: The central unit of the PIV system is installed in your home’s loft from where it can draw air into the property from outside through a filter – mounting the system higher above the ground level helps to reduce the amount of particulate matter that is drawn into the system which improves the air quality. Air from the central unit is diffused into the rest of your home to displace and replace stagnant or humid air.

Continuous Air Exchange: As the PIV unit operates, it continually supplies fresh air, diluting and displacing the existing air. This process helps maintain optimal humidity levels and prevents condensation and mould growth. Unlike more complex systems like Mechanical Ventilation with Heat Recovery (MVHR), PIV doesn’t require extensive ducting, which is why it is a popular retrofit option for existing homes.

Advantages of Positive Input Ventilation

Condensation Control: Damp and Mould Prevention: Everyday activities such as cooking, washing, and drying laundry release moisture into the air. Without proper ventilation, this excess moisture can lead to condensation on windows, walls, and ceilings. PIV helps maintain indoor humidity levels between 40% and 60%, effectively preventing condensation and black mould growth.

Cost-Effective: PIV systems are highly efficient in use with low running costs. A system such as EnviroVent ATMOS can cost as little as £9.07 per year at current electricity prices, and if the optional air heater is used, the annual running costs could be just over £60.

These costs are estimates, for up to date information around annual running costs please click here.

Retrofit Friendly Installation: PIV units are easy to install in the loft, making them ideal for retrofitting into existing properties. The single unit design of a PIV system creates effective ventilation without compromising airtightness.

Improved Indoor Air Quality: By continuously introducing fresh filtered air into your home, PIV systems reduce pollutants, allergens, and excess humidity. This contributes to better respiratory health and overall well-being for occupants.

Find out more

If you have discovered condensation or mould in your home, it is important to act quickly to prevent risks to your health. Our local ventilation specialists offer a free home survey where they will visit your property to identify the cause of condensation and provide advice about the best way to stop it permanently. Enter your postcode below to find an expert near you.

Need help with condensation, mould or damp problems?

One of our local experts will contact you to learn more about your problems, offer free expert advice and make recommendations for a permanent solution.

During the free survey we will

  • check Assess any condensation, damp or mould problems in your property
  • check Take readings of the relative humidity levels
  • check Identify any underlying problems and make recommendations for a permanent solution

Arrange a FREE Home Survey now