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 energy efficient

When replacing a fan, check the HVI rating and select fans that labeled "low noise" or "quiet."

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 manufacturer.

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.

6. 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.

Proper duct sizes are crucial. In most cases:

• Bathrooms need a minimum 4" ducts up to 6" for a large bath and fan.
• Clothes dryers need 4" ducts.

·         Follow manufacturer's 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 dishwasher.

Clean exhaust hoods of lint and nesting materials

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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