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Residential Fans


Ceiling mount fans with and without lights, heat/fan/light combos. Inline fans, wall mount, through the wall, motion sensing, humidity sensing, DC motor, recessed fan/light combos, decorative, high capacity and kitchen fans, there are many different styles of fans depending on your individual application.

We measure air movement in C.F.M. (cubic feet of air per minute), and refer the noise of a fan as the SONE rating.

Generally, you can calculate the amount of cfm needed by the square footage.
1 cfm per sq. ft. for ceilings height of 8-9 ft.  If you have a long duct run, that will need to be taken into consideration when you figure out the amount of cfm needed. 

The key to properly exhausting air is MAKE-UP AIR.  In order to exhaust air out, you must have someway to bring it in.  If you don't bring air in, you can't pull it out.  Most people incorrectly assume that if they just get a bigger fan, it will clear out the room better. That is not the case.  You MUST have make-up air.  Typically a window that is cracked open will work, if there is no window, crack open the door and open a window somewhere close by.  The other important factor is time.  You should leave the fan on for a minimum of 15 minutes after the shower.  The longer and hotter the shower, the longer you need to leave on the fan. 

There is only so much air you can push through a 4 in duct, which is usually what most people have in their bathroom. If you need more that 150 cfm fan for your bathroom, you will need to seriously consider changing to a 6in duct.


DUCT
A smooth surface duct allows for optimum airflow. For best results, use galvanized sheet metal or possibly PVC. Flexible aluminum duct is durable, easy to install and often used. However, the ridges in aluminum flexible duct increase static pressure and can reduce air flow and fan performance. This results in lower CFMs, higher noise levels and greater energy consumption. The degree to which performance is affected depends on the length of duct, number and degree of elbows.
Sagging or weaving a fan duct will also increase static pressure and reduce a fans performance. When using a flexible aluminum duct, support the entire length of the duct with braces or hangers to keep it as straight as possible for the entire run. If the duct lies across the attic, do not allow it to sag between each joist. Also, avoid weaving serpentine through trusses.
Using dryer duct connectors made of nylon or vinyl is not recommended due to high static pressure caused by its ridges and curvature. Insulated flexible duct must be fully extended to avoid added resistance.
duct-types

      ELBOWS
      Rule number one is to avoid elbows and bends whenever possible. However, the fact is that many installations require at least                   one elbow. There are two precautions you can take when installing elbows to achieve optimum airflow.
First, allow a 2-3 foot straight run out of the fan before the first elbow. This allows airflow to be uniform before passing through the first elbow. An installation that has a 90-degree elbow immediately after the fan exhaust port will cause air to flow back into the fan. This will reduce fan performance and increase noise.
Second, use a long radius angle to help ensure optimum airflow and minimum airflow noise. The shortest smooth, inner surface duct with the least number of elbows will provide optimum fan performance.
elbows



 


 

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