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I need to build a hushbox for a Sanyo XP21. I've done a number of searches here and have come up with an idea I think will work.

The projector is mounted directly to the ceiling and the box will surround it, being hinged for easy access to the projector.


For venting I'm thinking of running 6" flexible metal piping from the outlet of the projector, through the sheetrock and into the attic. Attached to the other end of the piping will be an inline fan to suck the air out http://www.smarthome.com/3011.html.

The only thing I don't know about these fans is their dB rating, i.e. how loud thay are.

My big question is whether I need to pull cool air in. I notice that the Whisperbox units only have output fans and no input fans.

So my options are:

1. No air input

2. Vents with air filters on the sides of the box for room ambient air.

3. Another inline fan pulling room temp. air from an adjacent closet


Any help is greatly appreciated.
 

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I've built a hushbox for LT150. Here is the picture http://www.avsforum.com/avs-vb/showt...threadid=89287


I've used two exhaust fans to draw the air out. Including the orginal two in LT150, there are four fans to drawing air into the hushbox. I don't think it needs intake fans. If there is intake fan, it may create pressure difference.
 

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Hi homebread,

Earlier this year I installed a whisperflow hushbox for a JVC G11U. I think some of the ideas might help. I ordered the hushbox with No fans for intake or output. I did not want any of the holes in the box except for in the top against the ceiling where I connected to duct work. I cut a 4" x 10" rectangular hole in the top of the hushbox. Then I installed a rectangular boot from inside the hushbox thru the ceiling into the attic space. The other end of the rectangular boot was made to accept 6" duct. I mounted a fan unit in the mechanical room of my house which is about 18' away. I ran 6" duct from the fan unit to the hushbox. I have the fan and projector connected to a current controll switch (bought at Sears), so when the projector comes on, the fan automatically comes on. It shutsdown when the internal fan of the projector shuts down. As a safety, I installed an indicator light in the hushbox that turns on when the remote fan comes on. Since the fan is in another room, I am unable to hear it turn off and on. I also installed a temperature prope mounted inside the hushbox installed by the air intake of the projector. The probe is connected to a LED display on the wall with an audable alarm. The fan is approx. 120cfm. For my application this is more than enough. The temperature inside the box when the fan is on is actually 1 degree coolor than room temperature.


I hope this gives you some ideas that help.


Good Luck!

DarrenW
 

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Homebread,


If you are using inline fans - also called "Radon" fans - they can be quite quiet.


Frequently there is a noise rating specified in "sones". The sones scale is linear while

the dB scale is logarithmic - so there is no constant conversion factor between the two.


Inline Radon fans - available from Fantech, deFlecto, Infiltec - were designed to mitigate

the problem of Radon seepage into homes by providing a constant exhaust of the room air.

Since they were designed to be left on continuously and have minimal impact on home occupants - they were designed to be quiet.


For relatively high flow rates - sufficient to cool even a hot D-ILA - quietly - inline Radon

fans, I believe, are the way to go.


Greg
 

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I used an in-line duct fan with 6" metal flex duct for my husbox outflow. I must say it's louder than I would have liked. I would investigate further if I were you. With JUST my husbox my room is basically silent. with the fan running there is a definite audible hum that is transmitted.


note: I didn't use that fan specifically. I bought one at a local hardware store. The link you had wouldn't come up for me.
 

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what is the price on that thing?
 

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The link in the initial post works -- youjust have to remove the period from the end of the url.


It says the 6" dia unit is 250cfm and tauts how quiet it is. And only $35 ! That is a bargain. I think 250cfm is more than enough for any projector and hushbox.


I'm using an intake and an exhaust on my husbox, pulling air in from a nearby closet and pushing air out to another room in the house. 80cfm on both fans. Which is not quite enough. I'm tempted to replace with the above.


I don't understand how hushboxes with only exhaust fans work. Either the hushbox is airtight and the fan will stop moving air as soon as a partial-vacuum develops, or the hushbox is not airtight and it will draw air in through whatever leaks exist. I think you need to design an intake port into the thing where the input air will be filtered. If the input is not ducted in from a remote location, however, you will have noise leaking out that intake port.
 
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