Bathroom exhaust fan


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Old 12-08-16, 06:05 PM
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Bathroom exhaust fan

I'm looking at adding a bathroom fan. Instead of a standard ceiling-mount fan, I'd like to put an inline fan in the attic. For some reason, I thought I be able to get the same performance for a better price that way.

So far, that hasn't been the case. I can get a quiet 100-150 CFM standard fan in the $75-125 range from Home DeLowes. The prices for inline fans don't seem to be better than that.

Except for these things called "booster" fans. I can find these with plenty of CFM for as low as $25. My question is whether these are appropriate for use as a bathroom exhaust fan. Some of them seem to hint that they should only be used in heating/cooling ducts. Others, which look nearly identical, say that they can be used for bath exhaust. Is there anything I need to be wary of in using a booster fan?

Thanks ... Tim
 
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Old 12-09-16, 04:06 AM
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Installing an inline fan in the attic is pretty straight forward. You would need to provide switching at the wall in the bathroom leading to the fan location in the attic. I have installed this type fan with good success. We used insulated duct and provided an exit lateral to the fan through the gable. I would not recommend punching a hole in an otherwise non leaking roof. Soffit vents are available if you are mounting it low in the attic. VENTS 162 CFM Power Whole House 4 in. In-Line Centrifugal Plastic Duct Fan-VK 100 - The Home Depot

As you noted they can come in a variety of prices and CFM ratings. Inline fans won't be cheaper than standard in ceiling fans.
 
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Old 12-09-16, 06:47 AM
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The most likely difference between booster and standard inline bath fans would be noise level, so I would compare that if it's important to you. And check the impeller material; you want plastic or aluminum because of the humidity.
 
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Old 12-09-16, 01:25 PM
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One post thought, too. When we installed one last week, we also put rubber washers between the unit and the rafter to dampen the vibration of the fan, which was little, but some.
 
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Old 12-11-16, 06:43 PM
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Most bathroom exhaust fans have a backflow damper. Inline fans will not have this damper.

A separate backflow damper is available and would be much better than the one that comes with a bathroom exhaust fan.

I use the 5C523 backdraft damper for 4 inch applications. It works best in vertical applications so adding some bends to the vent pipe is sometimes recommended.

I occasionally have to add one of these to bathroom fans that have an existing damper when outside air is still able to migrate into the bathroom and cause mildew around the supply air register.
 
 

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