What is a PIV System and How Does it Work?

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What is a PIV System and How Does it Work?
Positive Input Ventilation (PIV) systems are a popular and one of the most cost effective whole-house ventilation solutions for existing dwellings. They assist in creating fresh and healthy living environments by supplying fresh, filtered air into a property at a continuous rate.

There are two types of PIV, Loft Mounted and Wall Mounted

The Loft Mounted – This works by continuously pushing clean filtered air from your loft space in your roof area and distributes the clean filtered air via a ceiling mounted diffuser normally sited in your hallway or landing above or close to a stairwell. The stale and damp air is then forced out of the home through natural ventilation points, including areas such as trickle vents. There is also a Heated Version of the loft mounted system and that works by gently heating the cold air from your loft space avoiding very chilly air entering your home during the winter months, however, this does not work in the same way as a convector fan blowing warm air.

Wall Mounted Unit – These are usually used in flats and apartment type buildings as due to the non-availability of a loft area this works by taking air from the outside to a chosen room/area via ducting and continuously pushes the air through your home this way.
Would I need a PIV System

Would I need one?

Over the last 10 years or so, there has been increasing demand on builders, architects, and government legislation to increase the thermal efficiency of our homes. This legislation has lead to making new properties draught free and well insulated, which is great, but this has caused poorer air quality that can significantly increase the effects of asthma and other respiratory problems, health problems, condensation, mould, dust mites, unpleasant smells, and build-up of toxic gases as the buildings can’t breathe and the PIV can reverse these effects.

Something for The Landlords

Something for The Landlords

Keep your tenants happy and reduce your ongoing maintenance costs with the installation of a positive ventilation system (PIV). It’s successfully used to eliminate surface condensation, prevent mould growth and reduce house dust mite populations, especially noted in social housing around the UK.

Running Costs

These are very effective and efficient systems with an average annual running cost of approximately *£5 per year for the non-heated version of the PIV and the household heat demand for the heated version (our recommended model) could see costs of around *£300 per year depending upon energy supplier charges. Other costs would include the filters. Depending upon how dirty the loft space is would need replacing every 3-5 years with their price being around £50 and these can be changed by the homeowner.

There are various models on the market these days, however, we at SWES Ltd currently use PIV Systems manufactured by Nuaire & Envirovent with some of their variations offering 4 Way booster switches and humidity sensors.

*costs at the time of original post – February 2021


Whilst some PIV units can be fitted by any competent DIY’er, we do strongly recommend getting them installed by a qualified Electrician / Ventilation Expert to avoid any hazards that may arise.

For further product information, or to book a free no-obligation survey at your property, please contact us.

PIV Installation

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