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Whole House Ventilator Unit

Whole House Input Ventilators (Loft units) have been designed to create a continuous input of air (providing a capacity to move a maximum of 375m3 per hour). This will effectively combat condensation dampness and mould growth and meets or contributes towards the F1 Building Regulation requirements for ventilation .

Whole House Input Ventilator units create a continuous drying out process in dwellings and will help provide protection for hygroscopic material such as books, leather goods, wooden furniture, clothing and other fabrics from mould.

Energy Efficiency

Unlike conventional extractor fans, which suck out and waste expensively produced heat, the Whole House Input Ventilator utilises heat that exists in lofts through solar gain and simultaneously circulates existing heated air that has raised to ceiling height, heat which also helps increase temperature of the loft space air supply to the unit.

The continuous air movement throughout the property creates surface evaporation of moisture contained in the building fabric. This in turn, creates a drying out process, which means that there will be less hidden moisture to heat up increasing efficiency savings.

Whole House Input Ventilators consume less than a 60 Watt light bulb when in boost mode and less than a 40 Watt bulb when on background trickle.


  • Meets Building Regulations requirements Document F1 (Alternative methods)
  • Easy to install (no external access required)
  • Whisper quiet
  • Continuous Running trickle or boost ventilation
  • Humidity sensor (optional)
  • Low running costs
  • Positive input airflow
  • Security ventilation™ (no need to open windows)
  • Health benefit - produces dramatic improvements of indoor air quality
  • Heat energy dividend (solar gain)

Health Benefits

As long ago as 1989, an article in the British Medical Journal referred to the Health Hazards associated with condensation and mould growth in dwellings. The Statutory Fitness Standard clearly states that dwellings with inadequate ventilation, condensation and mould growth problems are unfit for human habitation and Building Regulation guidelines require a supply of fresh air and the removal of pollutants.

Whole House Ventilator Units, by reducing humidity to optimum levels, (eradicate condensation, prohibit mould growth and discourage the spread of bacteria, viruses and dust mite activity. By expelling dust particles, gasses and other household pollutants, the units create a dramatic improvement in the quality of the indoor air supply.

How it works

Condensation occurs when the water content of air rises above a level called the ‘dew point’. At such time, water droplets will form on the coldest surfaces e.g. windows, external walls etc. On average, a family of four people will produce about two gallons of water vapour per day from activities such as cooking, bathing, breathing and the washing and drying of clothes.

It is also a fact that nowadays most properties are insulated to prevent warm air from escaping. This reduction in ventilation allows the air contained within the property to reach a higher relative humidity.

Whole House Ventilator Units sited in the roof void draw in fresh air from the eaves. The air is warmed by Solar Gain in the loft space and is filtered and passed through ducting to discharge at landing ceiling level. The fresh air mixes with warm air rising up the stairwell and redistributes it throughout the entire property.

Each room is slightly pressurised and the continual air movement eliminates any stagnant pockets of moisture-laden air, which is eventually expelled through natural leakage points (window and door crevices, flues, air grilles etc.). In effect reversing the tendancy towards cold draughts entering the property.

An overall improvement in the internal atmosphere will be noticed within a few days.

Why specify a Whole House Ventilator?

Ventilation is necessary to maintain a healthy and comfortable internal environment and to rapidly remove pollutants such as moisture, volatile organic compounds (VOC’s), allergens such as dust, oxides of nitrogen, carbon monoxide, carbon dioxide, tobacco smoke and unpleasant odours.

Moisture is generally assumed to be the most significant of these pollutants because of the high rates of generation from cooking, bathing, washing, drying etc and the consequential condensation and mould growth problems. It follows that if the ventilation strategy is based on controlling this principle pollutant by input ventilation then logically the other indoor pollutants will also be adequately controlled.

Stale air, and air which is hot or humid, should be replaced at a reasonable rate. Good ventilation means providing a balance between energy efficient and healthy indoor air best summed up by the catchphrase ‘build tight – ventilate right’.

The fresh air supply rate should not normally fall below 5 to 8 l/s per occupant. This is best achieved by creating continuous air changes of 0.5 to 1.0 every hour, throughout the entire dwelling as specified in D.E.T.R. Good Practice Note 268.

Although building regulations relate to new buildings the guidance on ventilation is applicable to existing dwellings and, most important of all, the regulations are concerned with minimising the risk to health from the build up of pollutants. The KWH150 Whole House Ventilator satisfies all of these critera.