Ducted Fan

Posted on | November 12, 2008 | 3 Comments

Ducted Fan

What is the white cotton candy like substance growing in my attic on top of the Owens Corning pink Insulation?

My home is 16 years old. I have a standard peaked roof with plenty of ventilation to service my whole house fan which was installed at the time the house was built. This substance was just noticed this year when I was servicing the whole house fan. There are several clumps of the substance about the size of your fist or slightly larger.There are two bathroom exhaust fans which exhaust into the attic. They are ducted but the ducts end near the sheetmetal roof vents(5-6").Is this substance dangerous? what causes it? How do I get rid of it? Do I need to take any precautions when removing it?

I'd say that it is related to a moisture problem that stems from your incorrectly installed bathroom vents. They should NEVER be exhausted into the attic space -- period. Extend the vents through the roof so that the moisture being exhausted from the bathrooms will be moved outside. Mold and mildew are serious problems that need to be addressed by professionals.

ElectriFly XPD-8 EP HyperFlow Ducted Fan ARF

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How do whole house fans and attic fans compare?

I would rather install a good attic fan to push air directly outside -- instead of the whole house fan that is pushing air into my attic. What are the pros and cons of each of these options? Or can the whole house fan be ducted directly to an outside wall or the roof. I have a hipped roof, but gables a few gable walls in the front of the house...any ideas?

An "attic" fan, and a 'whole house' fan serve different functions.

The 'attic' fan, is of course used to help pull the trapped, heated (and often moisture laden) air out of the attic space. There are usually vents in the eaves or soffetts, to allow fresh air into the attic space. This helps extend the life of a typical shingled roof. Attics with no ventilation will quite literally, cook the decking, and roofing materials. An attic fan does not normally have any vents to the living quarters of the home itself...there is no exchange of air between the habitable portion, and the attic space. Most attic fans have a thermocouple switch (they come on when a built in thermostat registers the heat), and are automatic, and often low volume. A typical attic fan will burn about as much electricity as a standard 100 watt light bulb. The fan itself is often mounted inside the vent stack itself on top of the roof.

A 'whole house' fan, serves the purpose to pull fresh air thru the living quarters themselves. They are often vented to the attic, but not always (some are mounted on an end wall for example). These fans are also much larger than typical attic fans, and will pull a higher volume of air thru the home. It is important to note that if you have one installed to vent to the attic... you must make sure you have adequate venting to the exterior from the attic....or you're going to be trying to blow the attic up like a balloon, hehehe.. and it will not be as efficient as it could be. When the whole house fan is not operating, there is no benefit to your attic space from it, (assuming it is vented thru the attic space) and heat and moisture can build up inside the attic.

My advice would be to make certain the attic is adequately vented, whether you install a fan or not for that purpose.... you can use passive ventilation techniques, turbines, etc, instead of an electrically powered ventilation fan.

If you are looking for a way to cool the 'living space' of the home, then you want a whole house fan, not an 'attic fan'. You might try 2 or 3 window fans, in upstairs windows first.. theyre not expensive, and you can mimic the whole house fan effect, by using them to blow out the window. The key to this type of ventilation is to have the fan up high, and open some windows down low, so that the fan pulls the cooler air up thru the home. I'd try the window fans before I invested in a whole house fan, to see if I liked it. (I prefer an air conditioner myself, hehehe)

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