What causes the problems?

Did you know that 58% of people have suffered mould and condensation in their home? If you consider the fact that 90% of the time is spent indoors, it is vitally important to focus on improving indoor air quality (IAQ). It can damage not just he property, but health as well.

Cooking, cleaning and bathing

These activities generate up to 10 litres of moisture per day. In addition, every load of washing that is hung to dry inside adds an additional 2.5 litres. All together there could be 12.5 litres of moisture generated in the home every single day which can cause condensation and mould.

Volatile organic compounds

Substances like formaldehyde get into the home from things like paint, new furniture and cleaning products. The average person breathes 9,000 litres of indoor air each day, so poor indoor air quality (IAQ) can cause serious risk to health such as heart and respiratory diseases, and asthma being a key concern.

Increased insulation

In the drive to insulate our homes we have created an airtight box where, not just heat, but moisture and chemicals can’t escape. This causes poor indoor air quality, which can contain a cocktail of over 900 chemicals, particles and biological materials, which can have a negative effect on health.


What is Positive Input Ventilation (PIV)?

Positive Input Ventilation (PIV) is an energy-efficient method of ventilating the home. It pushes out and replaces stale unhealthy air with drier fresh air by gently introducing filtered air into the home and increasing the circulation around the property and improving the indoor air quality (IAQ). 

Ventilation removes the root cause of condensation and mould within the home. If a property has high levels of moisture, if left untreated this will allow mould to form causing further issues. By removing the moisture and other pollutants from the air, condensation cannot settle, and mould cannot grow which removes the problem at the source.

The Solution

Positive input ventilation (PIV) is one of the best solutions to tackle poor indoor air quality (IAQ). It is a solution for all types of properties, PIV units are usually situated in a loft or on a wall. Our PIV range offers both solutions whether you live in a house or a flat.

PoziDry Pro™ / PureAir Home
For properties with a loft

The PoziDry Pro™ can be hung from the rafters or mounted on the fully adjustable, anti-vibration feet to find the perfect loft location.

The optional F7 filters will remove almost all pollen from the air and help reduce diesel particulates.

With noise levels as low as 9dB(A) in the home, the unit can hardly be noticed when installed.


Lo-Carbon PoziDry™ Compact Pro
For houses without a loft and flats


The PoziDry™ Compact Pro is a small unit that can be installed almost anywhere, even boxed in entirely along with the ductwork, to provide a discreet and unobtrusive solution.

replaced filter

The product’s unique G4 or F7 filter choices make improving indoor air quality easy.


The unit comes with two blanking plates and one grille with adjustable airflow direction.

Find out more about the products


Watch a video

Read the PIV range brochure


Product features comparison

Range Stock Ref. Loft Mounting Wall Mounting Heater Data Logger 3 Storey Compliant Buy Now
PoziDry™ Compact Pro 479188    
PoziDry Pro™ 476310      
PureAir Home 479090        

Frequently Asked Questions

Positive Input Ventilation is a process which dilutes, displaces and replaces unhealthy air in the homes with clean, fresh and filtered air. A 'Heater' model can used to preheat the air if required. The ventilated air is delivered into a landing or hallway, and then gently ventilates all other rooms directly off the landing/hallway.

Moisture can move around the home; this happens when opening a bathroom or kitchen door after bathing or cooking. The pressure caused by heat will spread the moisture to other areas of the home, which can lead to mould growth in habitable areas. 

It is unlikely to increase the pressure because even refurbished homes that follow the latest building regulations will leak air. The supply air from the PIV unit will normally introduce around 21l/s for a three-bedroom house however, it would typically lose around 30l/s. This means less air is being introduced to the property.

There are numerous leakage paths for air to escape from in the home; such as letter boxes, key holes, trickle vents in windows, cat flaps, gaps and cracks around doors, windows and floors.

With an ultra-low power consumption motor, the PoziDry Pro™ can service a two bedroom house for less than £13 a year.

The heater set point can easily be adjusted by the ventilation specialist installer. The unit comes pre-set at 5⁰C and can be increased up to 20⁰C when installed. The heater element heats up and transfers the heat to the incoming air. The cost to run the heater will vary depending on the requirements of each individual home and energy prices, which will vary depending on the energy supplier and tariff.


The Building Research Establishment (BRE) tested Positive Input Ventilation and concluded that compared to extract fans with the same flow rate, households could save up to a maximum of 10% of the space heating costs. Compared to extract fans, which only extract air from the home, PIVs are an energy efficient method of pushing out and replacing stale, unhealthy air with clean drier air. This is achieved by gently introducing filtered air into the home and increasing the circulation of air around the property. The BRE found that loft spaces are around 3⁰C warmer than outside; this is more energy efficient than bringing in air directly from outside.


What customers are saying

We think it is an absolute no-brainer – the Vent-Axia Pozidry Compact beats (The Competition) hands down in our opinion."

Mike Davison, preservationshop.co.uk

We’ve been using the PoziDry Compact Pro since its launch, and it’s working very well for our customers – it’s proving to be a very good product."

Property Services, B3Living

The improvement of our indoor air quality is noticeable. We haven't had drippy window since we've installed this.

Satisfied Homeowner