Sunday, May 30, 2010

Bathroom Exhaust Fan

Exhaust Fan

Every bathroom MUST have an exhaust fan. Excess moisture in a home will destroy the finishes and possibly do damage to the structure. Excess moisture will foster mold and/or bacterial growth to cause an unhealthy environment. Warm air holds more moisture than cold air so when the bathroom temperature cools off the moisture in the air will end up on ceilings, walls and floors. Have you noticed all the moisture on a mirror after a hot bath or shower? That is because the mirror is a cool surface and the air here cannot hold as much moisture. But the worst senerio is when the moist air cools inbetween walls or if the warm air escapes into the attic where it then cools leaving the moisture behind on surfaces and unable to dry. This is the perfect conditions for rot to start working at the structure of the home.

Sometimes you will hear people say "you don't need an exhaust fan in the bathroom it has a window" you can just open it when you have a bath or shower. Right how many people do you know open the window when the outside temperature is at zero? Exactly zero!

The best exhaust fan is operated by a humidity control. The most comfortable setting is between 35 and 40% humidity. Set too low and it feels so dry that some people may get nose bleeds. Set too high and the air is not clear enough to breath comfortably. Each home depending on how many occupants and water usage will dictate the humidity setting. Many fans are never used because they make to much noise and so may be disconnected. Fans are judged by scones(amount of noise). A 1 scone is the quietest while a 3 scone may be the loudest. The better the scone the more the fan costs. Fans are sized for the square footage of the room they are to be installed in. I always say get an exhaust fan that is 50% larger than needed.

Always make sure that your exhaust fan exhausts outside, many just end in the attic. The exhausted moisture will condense with the cool air in the attic and cause major attic problems. The exhaust fan venting pipe/tubing should not have more than 2 bends. It should be as short in length as possible. The reason for this is because the moisture in the air being exhausted is heavy and without a very strong force the moist air will not make it to the end of the vent pipe. Exhaust fans have enough pressure to handle about two 90 degree bends and about 10 feet in length of pipe. This is the reason to size the fan you need a little bigger. The vent pipe should also be insulated on its exterior to prevent cool air contacting the vent pipe causing moisture to condense inside the vent pipe walls before it is exhausted outside the home. Make sure the vent has a proper closing exterior door so as not to allow bugs in or birds to enter the vent pipe and build nests.



Problem: Inadequate air movement. Inadequate air movement may be the result of obstructed, crimped or crushed duct work, obstructed exhaust hood, dirty fan blades and/or obstructed intake grille on the fan cover. Moist air is not being exhausted outside.

Problem: Fan cover missing. The fan and duct work are likely to get dirty faster with the cover missing. The fan blades and wiring are exposed and may be touched inadvertently.

Problem: Inoperative. Exhaust fans may be inoperative because of an electric problem or because the fan or motor is seized. If the fan is inoperative, it won't help reduce house humidity.

Problem: Missing. Moist air is not being exhausted outside. All bathrooms must have exhaust fans to get rid of moisture and unpleasant odors.

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