Domestic Property, West Sussex – Positive Input Ventilation and Extractor Fan Installation for Damp and Mould Prevention

The Problem

This terraced cavity wall home suffered from moisture management issues in rooms with high moisture generation; namely the ground/first-floor bathrooms and kitchen. These high humidity environments were more susceptible to excess condensation, which led to dampness and black mould growth on walls, floors and ceilings.

There was no pre-existing extraction system in the first floor bathroom and existing extractor fans were unresponsive to increases or decreases in moisture generation activity, which made them inefficient both in moisture management and energy used.

The kitchen also had no pre-existing ventilation system, which also contributed to condensation issues.

The Solution

To handle the moisture management demands of the building, a whole home approach that combines air extraction in high humidity rooms with positive input ventilation to introduce fresh air throughout the home was used. Dryzone Fans were chosen for their ability to bring down high levels of humidity.

Kitchen

The Dryzone Auto-Extract Fan is a low-profile damp control fan for kitchens, bathrooms and utility rooms. It automatically detects humidity levels and runs continuously at a low speed of 50m³/h to prevent condensation. It can be controlled via a remote switch or mobile app. An on-board data logger captures air quality details, temperature and humidity levels for optimised moisture management.

The Dryzone Auto-Extract fan was installed in the kitchen of this home to ensure regulated and continuous air flow that proactively prevents condensation. 

First, the installer bored a hole into the cavity wall through to the exterior. Then they fitted a PVC sleeve to the full length of the hole. An extractor housing was fitted, with a fan at the exterior end with the all-important moisture sensor facing the interior. Then the exterior vent cover was fitted, the moisture sensor was wired and the interior vent cover was fitted.

Bathroom

The Dryzone Inline Extractor Fan is an automated dehumidifying trickle extractor fan that automatically senses humidity levels and switches between low and high level extraction, depending on atmospheric conditions. The Dryzone Bathroom Extractor Fan removes air before it condenses to prevent damp and black mould. 

One Dryzone Inline Extractor Fan Vent was installed in each bathroom of this home to ensure that humid air is removed before it has a chance to condenses onto the walls and ceiling. With humidity levels in check, the fan ensures that the conditions for damp and black mould growth are never met. 

In the ground floor bathroom, a qualified electrician and contractor removed the existing non-smart extractor fan vent and made the wiring safe. The contractor cleared debris and dust from the existing ducting, then installed the new vent cover. There was no pre-existing extraction fan in the first floor bathroom, so a hole was bored into the ceiling board. Flexible ducting was fitted and joined to the existing extraction PVC duct pipe from the ground floor. Finally, a vent cover was installed. Finally, the installer removed a piece of existing PVC ducting (which connects to both bathrooms) in the loft to install the bathroom extractor fan. The joins were sealed to complete the job.

Whole Home Positive Input Ventilation (PIV)

The Dryzone PIV Fan was installed into the attic of this house to allow the intake and extraction of air. This dual box central system ventilation fan unit can be installed in lofts, utility cupboards, bathrooms, kitchens, basements or underfloor. When temperatures are below 14°C, it automatically heats the air to provide a pleasant home environment in the colder months. It produces up to 150m³/h of airflow to regulate the whole home. Internal humidity control and external air temperature sensors ensure accurate automatic ventilation regulation. The Dryzone PIV Fan works as part of a cross-flow ventilation system with the fans installed in the bathroom and kitchen. Low energy demands ensure low running costs and a long working lifetime. 

Introducing a steady flow of fresh and filtered air from outside into your home, balanced with sufficient extractor fans to remove humid air, is the best way to control the delicate moisture balance of a domestic living environment. Sufficient fan coverage hastens the drying-out time of an already humid atmosphere and shields the occupants from seasonal humidity fluctuations. Moisture control in this way also helps to protect structural wood such as roofing battens from damp and rot.

To install the Dryone PIV Fan, the qualified installer bored a hole into the ceiling board over the stairwell. They installed a vent cover, then fitted flexible ducting that connects to the Dryzone Inline Extractor fan vents before installing the fan.

The Results

We recorded the atmospheric conditions of the house before and after the fan installation, including:

• Temperature
• Dew point
• Water vapour concentration
• Humidity

Relative humidity reached highs of 89% prior to Dryzone Fan installation. After the fans started to manage the moisture in the home, they plunged to a low of 69%. This is important because human bodies struggle to regulate their temperatures in high humidity environments, due to how hard it is to remove heat through sweat evaporation at those levels, which makes it harder for your body to cool down.

The dew point improved from a high of 15.2°C before installation to the more comfortable 12-14°C range soon after installation. The dew point is the temperature at which air must be cooled to become saturated with water vapour. A cooler dew point alleviates the ‘sticky hot’ feeling that is uncomfortable for those in temperate climates.

Installing the Dryzone range of ventilation fans helps to meet compliance with the Building Regulations on Ventilation (F1) 2010 edition.