Problems and Humidity
in North/Central Texas
in Green Homes
Comfort, Home Maintenance, and Health
in Green Homes
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1. Noise. Many homes have
problems exhaust fans that are so noisy homeowners rarely use them enough.
This is particularly true when one person is using the bathroom while
another is trying to sleep.
Most fan labels have Home Ventilation
Institute (HVI) ratings so you can compare noise and energy efficiency. If
a fan is not rated, there is a good chance that it will be noisy and/or
When replacing a fan, check the HVI
rating and select fans that labeled "low noise" or
Vibrations also make fans noisy.
Wrapping fan housings and some duct sections in rubber or vinyl noise
barrier mats as well as using foam tape will stop some noisy vibrations.
2. Air Movement. A normal
bathroom needs a fan that draws at least 50 cfm. Find out if your exhaust
fan is drawing air by holding a piece of toilet tissue up to the grill. A
good exhaust fan will pull the tissue tightly against the grill. A kitchen
hood needs to move 100 to 300 cfm.
3. Venting. You should also
check the outlet to make certain air is leaving your house. In some homes,
builders merely vent the system into the attic. Exhaust air should not be
vented into the attic, a wall or ceiling cavity, crawl space, a basement
or into the roof soffit. This promotes condensation and mold growth.
4. Improper Installation or
Controls. Install exhaust systems according to the building code and
manufacturer's recommendations, using the proper controls. Controls which allow you to specify operating times or maximum humidity
levels are preferable to those where the operation is pre-set by the
Also see "backdrafting" under Cautions
5. Efficiency Start by looking at the
HIV rating again.
If you choose a fan with integrated
lights, look for efficiency. Look for a fan with replaceable parts and
permanent lubrication. A fan suitable for continuous use is preferable.
Range hoods are most efficient when they extend out over the stove surface and are close to the stove top which makes island units less effective than wall units.
Ducts. Straight, short duct
runs, with few turns or droops, will result in the highest fan flow.
Select smooth (low-resistance) ducts and seal the joints. Insulate
sections that run through non-conditioned spaces to avoid moisture
problems, then slant horizontal runs of duct down toward an exterior
outlet to drain any condensation outside.
duct sizes are crucial. In most cases:
instructions for kitchen exhaust ducts.
7. Improper Maintenance
Clean fans, housings, backdraft dampers, and exterior flaps seasonally
because dirt restricts air movement.
A typical bathroom fan can be cleaned
by pulling down the grill, and unplugging and removing the fan module.
Fans in ducts and exterior fans may be difficult to clean.
Range hoods usually have washable,
aluminum-mesh grease filters. Better quality filters have a smaller
diameter mesh over a larger surface area and can be cleaned in the
Clean exhaust hoods of lint and nesting
Plastic hoods break down over time and
need to be replaced.
Call Terry Jensen at 972 251-1532 or 817 545-0140.
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