PIV (Positive Input Ventilation) is a valuable tool in the fight against mould and condensation problems in our homes. Basically, it consists of a filter, a fan, and some ducting that draws in outside air, cleans it, and pumps it through the house, pushing stale air out.
It's an extremely useful method, but before you rush to get one fitted, you need to speak to the experts, like the amazing team at PIV Team. We are more than happy to share our knowledge on the subject to help consumers make the right decisions. After all, this is your hard-earned cash at stake! We want you to get the best results without spending a fortune or wasting your time and money.
In this blog, we're focusing on the length of time it takes for a positive input ventilation unit to take effect. It's a fair question; you've had it fitted to improve air quality and reduce condensation, so when will it start working?
To answer this properly, we need to understand how PIV units work, so we'll briefly explore this before moving on.
Positive Input Ventilation (PIV) is a home ventilation system that works by drawing in air from the outside, filtering it, and gently distributing it throughout the interior through the use of a fan that spins at a low speed. This process helps to reduce condensation, mould growth, and stale air, creating a healthier and more comfortable indoor environment.
PIV systems typically sit in the loft space (although they can be fitted to an external wall), where they draw in air from outside through an external vent. The incoming air passes through a filtration system, removing airborne pollutants such as dust, dust mites, pollen, and allergens. The filtered air is then distributed throughout the house via ductwork running through the ceilings or walls.
Learn more: How Does A PIV Unit Work
The introduction of fresh filtered air creates a slightly positive pressure inside the house. This positive pressure gently pushes stale air out of the house through natural leakage points, such as trickle vents and gaps around windows* and doors. This continuous cycle of clean air intake and stale air displacement effectively ventilates the entire home, improving indoor air quality and reducing moisture levels.
*Open windows can make mould problems worse during colder months
By introducing drier air from outside, PIV helps to regulate humidity levels, preventing condensation and mould growth. PIV systems are generally energy-efficient, as they operate at low power and don't require heating or cooling the incoming air.
The term refers to the way that all the air is pumped in rather than drawn out of the property, as you get when using extractor fans. Drawing air out of a space creates negative pressure, with more air rushing in to fill the space.
PIV units, on the other hand, push clean air in, which raises the pressure and forces stale, humid air out through the gaps.
Check out: What Is A PIV Unit
The actual unit will begin working from the moment the switch is thrown to turn it on. However, the effects vary depending on the type of unit and the size of the property.
Generally, they will draw air from the loft space and pump it through the entire property within a few hours of being installed, and some customers reported feeling the effects almost immediately.
Realistically, though, it may take a few days to start working fully.
The time it takes for PIV systems to fully replace the stale, humid air in a property depends on several factors, including the size of the property, the airflow rate of the fan, and the number of air changes per hour (ACH) desired. In general, it can take several days for the unit to achieve a full air change in a property.
Here is a more detailed explanation of why a PIV unit takes a few days to start working fully:
When it's first turned on, the fresh air does not immediately mix evenly with the stale air in the property. Instead, the fresh air tends to stay in the upper part of the property, while the stale air remains in the lower part. This is because fresh air is less dense than stale air, so it rises naturally.
Over time, the fresher air gradually displaces the stagnant air, as the two types of air mix together. This process is accelerated by the movement of people and objects in the property, which helps to circulate the air.
To achieve a full air change in a property, the PIV unit needs to operate for several hours per day. The number of air changes per hour (ACH) is a measure of how many times the air in the property is replaced each hour. A typical Positive Input Ventilation system will achieve 2-3 ACH, which means that it will take about 3-4 hours to replace the air in a property once.
The time it takes for PIV units to fully replace the air in a property can also be affected by other factors, such as the size and layout of the property, the number of occupants, and the weather conditions. For example, a larger property with more occupants will take longer to ventilate than a smaller property with fewer occupants. Additionally, cold weather can make it more difficult for PIV units to achieve a full air change, as the new air will be colder and denser than the stagnant air.
Here are some additional tips for getting the most out of your PIV:
Here's something you need to be aware of, and it's important: technically, a Positive Input Ventilation unit won't get rid of black mould!
What it will do is balance the air temperature in your home, removing excess moisture and humidity that leads to condensation problems as it settles on cold surfaces. This will drastically reduce the possibility of mould and condensation issues, but any existing black mould will need to be removed before the PIV unit is fitted.
After a few weeks, when the system has had a chance to take full effect, you'll probably notice that the mould has not reappeared.
To round up our blog, we'll give you a few more details on PIVs to help you come to a conclusion as to
No, PIV units are actually very quiet! The fan unit is typically located in the loft or attic, and the ducting is designed to minimise noise transmission. The sound level of a PIV unit is typically around 14 dB(A), which is about as loud as a whisper.
The cost will vary depending on the size of your property and the complexity of the installation. However, as a general rule of thumb, you can expect to pay between £500 and £2000 for a complete system, including the price of the equipment and the installation.
No, PIVs generally do not make houses feel cold. In fact, they can help to keep your home warmer in the winter by recirculating warm air from the loft or attic. PIV systems can also be equipped with a pre-heater, which will help to warm the incoming air to a set temperature before it is introduced into your home. This goes into standby mode if the temperature exceeds a certain limit.
However, PIVs can make a home feel cold under certain conditions, usually during the winter months, because cold air is blown through the property. Please see our other blog post about this subject for more information.
Dig Deeper: PIV Unit Making House Cold
It is not recommended that you install a PIV yourself; it should be installed by a qualified electrician or ventilation engineer, like the expert fitters at the PIV Team.
No, the running cost of a PIV unit is approximately 1-2p per day! That makes them an incredibly cost-effective ventilation solution.
It's essential to understand all the facts before making a decision. While the PIV Team wholeheartedly endorses the benefits of Positive Input Ventilation, we know that it's not the right solution for everyone.
We offer sound, impartial advice and will recommend other solutions (such as mechanical ventilation with heat recovery) where we believe they are a better investment.
Finally, to summarise our main point, a PIV unit starts working straight away to improve the air quality and reduce condensation, although it might take several days for the fresh filtered air to make a difference.
