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Positive Input Ventilation: Pros and Cons

Positive Input Ventilation

Ventilation is ventilation, right? Well, no. Different types of ventilation, while achieving similar results, work in different ways which may better suit your needs. Consequently, you really need to look at all types - MVHR, PIV etc. - to understand the differences. This article discusses Positive input ventilation: Pros and cons.

Ventilation Megastore manufactures, and sells, only Mechanical Ventilation with Heat Recovery (MVHR), but we think it is important for you to have all of the information you need to make the correct, educated choice for you.

In some circumstances, PIV will be the way you need to go, or you may simply prefer how it works for your property.

Now, Let's look at what PIV is, and how it works.

Positive Input Ventilation
An example of a Positive Input Ventilation unit from Vent Axia

What is Positive Input ventilation (PIV)?

Positive Input Ventilation (PIV) is a type of ventilation system that works by drawing fresh air from outside and subsequently circulating it throughout the property. Installation in new and existing properties is an effective solution for improving air quality, reducing condensation, and preventing mould growth.

Looking to improve your home's air quality? Consider positive input ventilation! In this article, we'll explore the pros and cons of PIV systems, helping you make an informed decision about whether they're right for your home.

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Pros of PIV

Improves indoor air quality

PIV works by constantly circulating fresh air throughout the property. This helps to remove pollutants, allergens, and other harmful substances from the air, improving indoor air quality. This is particularly important for people who suffer from allergies or respiratory issues.

Reduces condensation and prevents mould growth

Condensation is a common problem in many properties, especially in colder months. PIV can help to reduce the amount of moisture in the air, preventing condensation from forming on windows, walls, and ceilings. This, in turn, helps to prevent mould growth, which can cause serious health problems.

Read more about the problems caused by condensation in our previous article What Causes Condensation?


PIV is an energy-efficient solution for ventilation. It uses a low-wattage fan to circulate air, which is much more efficient than other forms of ventilation, such as extractor fans. This can help to reduce energy bills and lower carbon emissions.

Easy to install

It is relatively easy to install PIV without major disruption to the home. You can fit PIV to existing ducting, or install a new system, depending on the needs of the property. This means that homeowners can enjoy the benefits of PIV without having to undergo major construction work.

Low maintenance

PIV requires very little maintenance, making it a hassle-free solution for homeowners. The filters need to be changed regularly, but this is a simple task that can be done by the homeowner.

Positive Input Ventilation

Cons of PIV


One of the most common complaints about PIV is that it can be noisy. The low-wattage fan used in the system can produce a humming noise, which can be disturbing to some people. However, newer models are much quieter than older ones, so this is becoming less of an issue.

Initial cost

In addition, the initial cost of installing a PIV system can be quite high. However, this cost can be offset by the energy savings that are achieved by using the system. In addition, many manufacturers offer financing options or payment plans to make the cost more manageable.

Not suitable for all properties

PIV is not suitable for all properties. It works best in properties that have a high level of air leakage, as it relies on the flow of air to circulate throughout the property. In properties with very low air leakage, such as modern, airtight homes built to building regulations, it may not be as effective. In addition, PIV may not be suitable for properties located in areas with high levels of pollution or allergens.

Potential for drafts

PIV can cause drafts in some properties. This is because the fresh air is circulated throughout the property, which can create a flow of air that can be felt by occupants. This is not a major issue, but some people may find it uncomfortable.

May not be effective in all climates

PIV may not be as effective in all climates. In cold climates, it may not be as effective at reducing condensation, as the air that is brought in from outside will be cold and may increase the risk of condensation. In very hot climates, it may not be as effective at reducing indoor temperatures, as the air that is brought in from outside will be hot.

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PIV is an effective solution for improving air quality and, in addition, reducing condensation in the home. It is energy-efficient, easy to install, and low maintenance, making it a popular choice among homeowners. However, it is important to consider the potential drawbacks, such as noise, initial cost, and the potential for drafts, before making a decision.

If you are considering installing a PIV system in your home, it is important to consult with a professional to determine if it is the best solution for your specific needs. They can evaluate your property and climate to determine if PIV is suitable and recommend any other types of ventilation that may be more effective.

Overall, PIV is a great solution for improving indoor air quality and reducing condensation in the home. It has many benefits, including energy efficiency, ease of installation, and low maintenance. However, it is important to carefully weigh the pros and cons before making a decision.

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