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Sub Floor Ventilation

Sub Floor Ventilation

Poorly ventilated sub floor areas are often damp. Dampness can result in mould, mildew, musty odours, wood rot and pest infestation in your sub floor area and can also contribute to the spread of mould, mildew and allergies above.

Sub floor ventilation can remove ground moisture from underneath raised floors, creating a drier and warmer sub floor area.

Pest and building inspectors recommend sub floor ventilation to reduce termite risk.

All of our sub floor ventilation systems are available with installation or as a DIY kit.

We have provided you with the following detailed information to assist you with sub floor ventilation. We encourage you to call us on 02 4855 1025 or to submit an enquiry by CLICKING HERE if you have any questions or would like a FREE home assessment.

Positive Pressure, Negative Pressure or Balanced Pressure?

Depending on how your sub floor ventilation fans are installed, they will either blow air in (positive pressure) or suck air out (negative pressure) of your sub floor area.

Fresh VHC offers three sub floor ventilation fan configurations:

Sub Floor Ventilation Fan Configurations

Positive Pressure

  • One or more fans are installed so that the amount of air being blown in is greater than the amount of air being sucked out of your sub floor area.
  • By continually forcing fresh air in, a positive pressure is created in your sub floor area so that musty damp air is pushed out.
  • Blowing dry air across damp surfaces may dry them faster than sucking moist air from around them.
  • If air cannot escape freely from your sub floor area, there is a risk that moisture or musty odours may be pushed into your home above.
  • Typical Positive Pressure Sub Floor Ventilation Systems:
  • 1 Positive Pressure Fan
    2 Positive Pressure Fans
    2 Positive Pressure Fans  +  1 Negative Pressure Fan

Negative Pressure

  • One or more fans are installed so that the amount of air being sucked out is greater than the amount of air being blown into your sub floor area.
  • By continually extracting damp air out, a negative pressure is created in your sub floor area so that fresh dry air is pulled in.
  • Moisture and musty odours can be controlled since air is sucked out at a chosen location.
  • Sucking moist air from around damp surfaces may dry them slower than blowing dry air across them.
  • Typical Negative Pressure Sub Floor Ventilation Systems:
  • 1 Negative Pressure Fan  -  Top Seller
    2 Negative Pressure Fans
    2 Negative Pressure Fans  +  1 Positive Pressure Fan

Balanced Pressure

  • Two or more fans are installed so that the amount of air being sucked out is equal to the amount of air being blown into your sub floor area.
  • Fresh air is forced in at the same rate damp air is extracted out, creating a balanced pressure and giving you the best of both worlds.
  • Maximum drying since dry air is blown across damp surfaces and moist air is sucked from around damp surfaces.
  • Maximum coverage and cross-flow since dry air is being blown in and circulated at one end of your sub floor area, while damp air is being sucked out at the far end of your sub floor area.
  • Moisture and musty odours can be controlled since air is sucked out at a chosen location.
  • Typical Balanced Pressure Sub Floor Ventilation Systems:
  • 1 Positive Pressure Fan  +  1 Negative Pressure Fan  -  Top Seller

Sub Floor Ventilation Components

Our sub floor ventilation systems use components that have been carefully selected for their purpose. We use only the best components to ensure that you get superior performance, proven reliability and lower operating costs.

We have experience with a range of European inline mixed flow fans, such as Blauberg (Germany) and Vortice (Italy).

We predominately use and recommend premium centrifugal fans manufactured by ebm-papst in Germany. Centrifugal fans have superior noise and performance characteristics when used in a ducted system.

AC Motors vs EC Motors

AC motors are significantly cheaper than EC motors.

AC motors are designed to be operated at one fan speed only (where they are most efficient).

EC motors are significantly more efficient than their AC counterparts at all fan speeds.

In real world use, EC motors provide:

  • Significantly higher air flow
  • Less noise
  • Smoother fan operation
  • Significantly more efficient (a 20% reduction in air flow typically equates to a 50% reduction in energy usage)

Sub Floor Ventilation System Sizing and Fan Selection

When determining which sub floor ventilation fan is most suited to your home, it is important to consider:

  • Fan configuration (positive, negative or balanced)
  • Proper system sizing to ensure sufficient air flow and effective ventilation
  • Construction materials of your home and its surroundings to ensure quiet and unobtrusive operation
  • Design effectiveness
  • Aesthetics
  • Price

AC Motor Centrifugal Fans

Our AC motor centrifugal fans have the following qualities:

  • Single speed
  • Approximately 560 m³/h air flow and 52 W power usage
  • Low noise during operation
  • R2E190 motor manufactured by ebm-papst in Germany
  • 3 year warranty
  • IP 44 protection rating

EC Motor Centrifugal Fans

Our EC motor centrifugal fans have the following qualities:

  • Variable speed
  • 310 m³/h air flow and 10 W power usage
  • 445 m³/h air flow and 24 W power usage
  • 580 m³/h air flow and 49 W power usage
  • 735 m³/h air flow and 83 W power usage
  • Very low noise during operation
  • R3G190 motor manufactured by ebm-papst in Germany
  • 3 year warranty
  • IP 54 protection rating

Portfolio

AC Centrifugal Sub Floor Fan
AC Motor Centrifugal Sub Floor Fan
Two fans were installed to extract musty air from a damp sub floor area in Wollongong. The 'negative' system was designed with flexible duct to take air directly outside from problem areas.
Wollongong - February 2015.

Anodised Aluminium Weatherproof Sub Floor Grille
Anodised Aluminium Weatherproof Sub Floor Grille
The grille is the same size as two bricks (and installed as a direct replacement). It is weatherproof and perfectly suited for damp sub floors and coastal areas since it will not rust. It can be directly connected to a fan or flexible duct to ensure moist sub floor air is not being recycled.
Canberra - September 2014.

Fan Connected via Flexible Duct to the Back of an Anodised Aluminium Weatherproof Sub Floor Grille
Fan Connected via Flexible Duct to the Back of a Sub Floor Grille
Flexible duct connects the fan to a back box on the back of the grille. This ensures that fresh air is brought in from outside or moist air is taken outside (rather than being circulated in the sub floor area).
Wollongong - February 2015.

Inline Sub Floor Fan
Inline Sub Floor Fan
Two fans were installed in a damp sub floor area in Bowral. The 'balanced' system was designed with flexible duct to blow fresh air in at one end and extract moist air out at the other end.
Bowral - May 2014.

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