Positive Pressure Ventilation

Positive pressure or roof cavity ventilation systems are the most common type available in New Zealand. The positive pressure home ventilation system works to create a drier home environment for you and your family.

Bringing filtered air from the roof space or outside into the living spaces through a single, or multiple, ceiling vents. This forces the stale air to leak out through gaps, windows and doors, taking it through a filter (such as HRV’s Nanofibre filtration technology) and distributing it throughout your house via a fan and a series of ducts.

Positive pressure ventilation systems are the most effective way to reduce water vapour in your home. The system continuously ventilates your home, significantly reducing problems like crying windows, mould and mildew and helping to improve the overall indoor air quality, making your home a healthier one.

These ventilation systems rely on natural air, creating a ‘positive pressure’ which gently pushes the stale, moisture-laden air out of your home to replace it with drier, fresher, filtered air from the roof space, or outside the house. DVS Positive Pressure Ventilation Systems are suitable for older houses with wooden joinery better than modern houses with sealed aluminium joinery.

Lower initial costs

– they’re relatively cheap to buy and don’t tend to need lots of ductwork.

Easy installation

– everything can be mounted in the roof space with a power source and a duct through the hallway ceiling or other central location. You can also have a second duct to bring air in from outside rather than taking it from your roof space.

Cheap to run

– run by small fans, they don’t add much to the power bill.

The most common type of Positive Pressure Ventilation System consists of a loft unit fitted into the roof void. Some systems are supplied with a pre-heat facility which heats the air before it is pushed down into the property, and controls for both heating and fan speed are usually located on the wall in the landing area.

Other types of systems are available for properties where access to the loft space is limited, such as flats, for example. These systems are fitted on a convenient wall, as close to the air intake point as possible.

They are commonly situated inside a hallway cupboard where access to an external wall and ambient air intake is possible. Supply ducting is run to an outlet air grille, often situated in the hallway, to ensure that there is even distribution of air throughout the property from a central point. These systems are usually fitted with pre-heat facilities as standard.