PIV Ventilation

PIV Ventilation

PIV Ventilation Systems

Positive input ventilation (PIV) is a ventilation system that can easily be installed in existing houses but can also meet the ventilation requirements for Part F of the building guidance for new build houses. This system is suited for houses with attic spaces and also apartments. The system is especially suited for houses which have a stove installed as the unit creates a positive air pressure reducing the risk of gas spillage from the stove.

How the System Works

Depending on the PIV model selected you can take fresh air from outside either through a well ventilated attic space or directly from a wall vent as would be the case for an airtight attic or an apartment. The air passes through a filter coming into the unit and is heated up to 10 degrees before it is delivered into a central spot of the house such as the landing space.

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The reason a PIV system works so well at curing condensation and mould problems is that the unit brings in a controlled amount of air into the house 24 hours a day and is constantly diluting and pushing stale air out of the house. During the winter months the air is always drier outside no matter what the weather conditions are unless we get a day over 20 degrees. The reason it is drier outside is because of the temperature, every 10 degrees the temperature drops the amount of moisture the air can hold is cut in half. So if your house is at 20 degrees and 100% relative humidity while outside is at zero degrees, the air outside can only hold a maximum of 25 % relative humidity when heated to 20 degrees. So if you keep introducing dry air in at a low rate, the humidity level will be kept below the level that promotes the growth of mould.


The performance of the PIV unit can be further enhanced with the use of constant running fans in the bathrooms and utilityroom. When the PIV unit is installed with constant running fans (dMEV Fans) , this will create a very efficient ventilation system with a very low maintenance and running cost.


To find out more about how PIV works, please
watch this video. or download a brochure.

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We supply and fit a range of PIV units from Envirovent and Elta fans. Each unit is suited for different locations and type of properties. We recommend that you contact us first to find out more about the benefit of the different units and which unit is most suited to your needs. Below are some of the units we use for different situations.

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