What Is Positive Pressure Ventilation In Buildings?

What Is Positive Pressure Ventilation In Buildings
The simple answer to the question, ‘What is positive pressure ventilation in buildings?’, is that it helps to reduce problem condensation and black mould.

And if you have never heard of positive pressure ventilation (PPV) systems, then they are an easy way to replace the moist air in a property with fresh filtered air.

The reason why PPV systems have grown in popularity is down to the development of new houses – but they can be installed in older properties too.

That’s because modern homes have been made more airtight to help with keeping them warm in winter, but this then leads to issues with condensation, mould and damp because there is no air flowing through the property.

What are positive pressure ventilation systems?

To help boost – or create a flow of fresh air – a positive pressure ventilation system will provide that continuous ventilation within a home without creating a cold draught.

The system itself is straightforward to install and consists of a small fan that is placed in the loft space which will force fresh, filtered air through the property using ceiling vents.

This forced air will then push the stale air through the gaps around windows and doors and other areas where the air will leak from a property.

The system works more efficiently when doors and windows are closed.

By removing this stale air, homeowners will then prevent the build-up of condensation and restrict the growth of black mould.

One example of a positive pressure ventilation system is the Drimaster DRI-ECO-HC Condensation Ventilation Loft Unit:

It has been highly rated by users and comes with a hall control and a seven-year warranty.

An alternative is the Nuaire Drimaster Eco heat condensation control PIV bundle with comes with a hygrometer to measure the level of water vapour in the air of the property:

Nuaire Drimaster Eco Heat Condensation Control PIV Bundle for Lofts with Hygrometer
232 Reviews
Nuaire Drimaster Eco Heat Condensation Control PIV Bundle for Lofts with Hygrometer
  • Drimaster Eco Heat with 400w integral heater. Compatible with optional controllers and sensors. Free i-sells digital hygrometer included.
  • For homes with lofts for whole house ventilation. Complete with a FULL 7 Year Nuaire warranty.
  • Supplied with all required parts for installation, no additional ducting required.

How positive pressure ventilation works

The important aspect of a positive pressure ventilation system is that it will draw in fresh air from outside of the property, and then ‘dry it’ to an ambient temperature.

The system then gently pushes the clean air using the fan system throughout the home.

However, depending on the property, a PPV may not be the best solution for those homes with mould and damp problems.

That’s because the success of the system’s installation will depend:

  • On the fan’s performance;
  • The building’s airtightness;
  • The distribution of ceiling vents.

So, for a property that is particularly draughty, a PPV will struggle to force the dry, ambient temperature air into the rooms so any moist air already in there may remain.

Also, the roof space will need to be sealed properly so the air that has been forced through the property is not then moving to the loft space where it could be re-circulated.

If that happens, it will defeat the object of having a PPV installed.

It’s also worth mentioning the issue of negative pressure ventilation in a home.

An example of this would be an extractor fan, usually located in a bathroom or kitchen, and they suck air from a property, rather than pushing it in.

This then leads to negative or low pressure in the property – and the higher-pressure air outside the home will then be drawn into a property via the gaps, such as those around the windows.

Why does a property need a PPV?

One of the big issues for modern house design is the lack of adequate ventilation because this leads to a build-up of excessive moisture and humidity inside.

In turn, this could lead to serious health issues for those suffering from allergies or asthma as the condensation then creates damp and black mould.

The damp and mould may appear on cold surfaces such as windows and walls and lead to black mould growing in damp areas, such as the kitchen or bathroom.

In a modern home, having effective ventilation is crucial and the PPV system will be designed to help improve the flow of fresh air.

The other big takeaway from installing a PPV system is that it should not be seen as being the best solution to a damp problem – that depends on the age and design of the property.

We mention below a potential alternative, however, the PPV system may prevent the build-up of mould in most properties.

Why use positive pressure ventilation systems?

Black mould is one of the reasons why many people want to install a positive pressure ventilation system in their homes.

There is a range of benefits for using a positive pressure ventilation system including:

  • It will remove moist air to prevent condensation;
  • It will prevent black mould from growing;
  • The system will be low maintenance;
  • The system filters have a large capacity for maximising ventilation;
  • PPV systems are cheap to run;
  • The PPV is very quiet – those living in a property are unlikely to hear it.

While these benefits are the main considerations, there are other issues to take into account, including:

  • There are variable speed and air volume settings for the fan;
  • Modern systems will not pre-heat the air when the exterior ambient air temperature is over 25°;
  • Newer systems also have a ‘blocked filter’ warning light to warn when it needs changing or cleaning.

What types of positive pressure ventilation systems are available?

Usually, a positive pressure ventilation system will be installed in the loft and then have an air diffuser ducted to it.

Some systems have a pre-heat facility so that the air is warmed up before being pushed down through the air vents.

For flats, where there is not a loft space, a convenient wall with a duct air intake point, is a possibility.

The flat owner will need to duct the system to an outlet grille to help distribute the air evenly throughout their property.

Why should I install a PPV system?

Along with reducing problems with black mould and condensation, there are other positive reasons for installing a PPV system.

  • A PPV system will improve your home’s air quality;
  • Homeowners can preset the PPV settings to suit;
  • Some systems have pre-heat facilities to maintain comfort levels – which helps with the heating bills;
  • The airflow will be consistent when the system is in use.

Also, a qualified electrician should install your positive pressure ventilation unit and they should follow carefully the manufacturer’s instructions.

A PPV unit has been designed to be flexible and they are very easy to install.

Can I use a PPV system in my property?

Generally, a positive pressure ventilation system can be installed in most properties – though you need experts to do this and access to an exterior wall.

They may not be suited for every type of property, and for new builds:

  • New homes tend to be well-insulated with good draught-proofing but a PPV can still be used
  • New properties tend to have good levels of airtightness so the stale air will struggle for somewhere to go – and lead to the PPV unit coming under stress.
If you ever wondered what is positive pressure ventilation in buildings, you should know that new homes might not be well suited for a PPV system.

The other issue for those with a new build property is that a PPV may not be the ideal solution and it may be worth looking at a mechanical ventilation and heat recovery (MVHR) system instead.

The issue here is that you will not be forcing cold air into what is a warm home.

One issue for those homes built before 2010 is that they do not suffer from condensation as modern homes do.

That’s because they weren’t built to be airtight, so the building itself does the job of the PPV system.

Modern homes tend to be well-insulated and airtight so owners of older homes will seal the gaps in wall cavities, roof spaces and window frames.

That will keep the heat in a home and reduce draughts.

The downside is that the moist air that is in the property will not have the opportunity of escaping, and it is this that will cause condensation and create black mould.

The advantages of installing a positive pressure ventilation system

There are some positive reasons for installing a PPV system including:

  • They are cheap to buy;
  • They will not need lots of ductwork;
  • They are easy to install;
  • They are cheap to run.

By installing a PPV system you will be improving the home for those with allergies and improving ventilation for the entire property.

This will also reduce musty smells, the growth of black mould and having stagnant air in the property.

Another positive feature is that homes will no longer suffer from damaged paintwork or peeling wallpaper.

The disadvantages of installing a positive pressure ventilation system include your heating costs rising because you will be pushing cold air from outside into the home – unless you invest in a preheating PPV system.

Not every home is suitable for PPV

Flat owners need to be careful where their PPV unit is installed. You will need a specific wall-mounted unit, and these usually have an in-built heater and a range of running speeds.

It’s worth highlighting that the first downside of seeing heating costs rise also means that simply opening a window to reduce condensation will also make a heating system work harder to heat the property.

Why a PPV system is worth the money

For anybody who is experiencing problems with persistent black mould and condensation in their home, then a positive pressure ventilation system could be the answer.

Increasing the flow of clean, fresh air throughout the property and removing stagnant air will generally improve air quality and reduce condensation.

PPV experts highlight that for those homes struggling with condensation problems, your rooms will be transformed between four and six weeks after having a system installed.

This means that for a relatively inexpensive outlay, your property will be condensation-free with healthy air for those living there to breathe.

And for many people, understanding how positive pressure ventilation works in their home could lead to a reduction in black mould and condensation and boosting the air quality will be reason enough for making an investment.

Our recommended Positive Pressure Ventilation systems:

Nuaire Drimaster Eco Heat Condensation Control PIV Bundle for Lofts with Hygrometer
232 Reviews
Nuaire Drimaster Eco Heat Condensation Control PIV Bundle for Lofts with Hygrometer
  • Drimaster Eco Heat with 400w integral heater. Compatible with optional controllers and sensors. Free i-sells digital hygrometer included.
  • For homes with lofts for whole house ventilation. Complete with a FULL 7 Year Nuaire warranty.
  • Supplied with all required parts for installation, no additional ducting required.

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