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I want to put g15 behind optical glass with a cooling fan and intake vent. It is in a bookshelf cabinet with other electronics, but is by itself above the top shelf, and mounted to top of cabinet with a ceiling mounting bracket. It is too loud. Space will be about 15" high x 23" deep x 40" wide.


Does anyone know: How many cubic feet of fresh air per minute should it get?


Thanks

Randy
 

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Randy,


Check out some pretty good info here that I got awhile back.


Chris
 

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Sorry Randy,


I missed the point of your question. I tried a search awhile back on that for my own install, but couldn't find anything either. Perhaps a call to JVC would do it.


Chris
 

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Hi Randy,

I am in the midst of building a hush box 21.5"H by 23"D by 28"W for my G11. When I was researching the in and outs of building a box on this forum, I came across the information below. I don’t no where the post resides now as I copied the info I needed to WORD. I figured I needed to move about 135 - 150 CFM by the calcs below. I purchased two "ebm industries" model 4212NGML, 12Vt fans ($29.20 each plus shipping) ebm.com . They each move 75CFM and will operate between 7 and 14.5 Vts. DC at aprox 200 ma each at 12 Vts. I have a filtered opening 6" X 16" in the bottom of the box with the area baffled for noise control. You can purchase a selectable DC 6vt - 12 vt wall wart (mine is rated at 800MA to handle a 3rd fan) for about $20. I purchased it locally at an electronics supplier. My box is higher than normal as I will have to hang it over the 6" x 6" beam that my G11 is attached to. When I tried out the fans they were moving a fair amount of air but putting my hand at the inlet there wasn’t as much flow as I would have expected. I removed a baffle plate and it got better but the noise of the fan is a little louder coming through the inlet. With the beam and projector taking up space in the box, the volume will decrease. I also cut and then temporarily plugged a third hole in the top of the box to handle an additional fan if necessary. Best to plan ahead. You have a large volume and may need three fans. I am using MDF (like in speaker construction) that will more than likely need some sound insulating material added inside the box. I am going to try it first without it as good mylar sound insulating material is very expensive. I am probably within a few weeks of the actual installation. Other Spring projects starting to take priority. Also the fans are fairly quiet, BUT I needed to mount them using rubber grommets to isolate a fan motor wine I was getting transmitted to the structure. I have purchased a 10" X 8" piece of optical glass at $41.00 (Ugh).


Hope this helped, Don A.


Quote:
Hello All!

I've got a d-ila on the way (Yaa!). I've also gathered that during the loudest parts of a film I just might not be able to hear it. A Killer Hush box is needed!!!

A totally sealed box with air blown in/out from outside the room seems in order. I got looking into the heat these babies put out and I found a page that has a formula for CFM required to cool the enclosure:

CFM = (3.16 x Watts) / T

where T = the inlet air temperature.

The url where I found it is:
http://www.users.dircon.co.uk/~nmb/f.../data/info.htm

I've seen the same formula on an unrelated page so I don't think it's specific to what this company does.

Plugging in 620 watts and a 15 degree rise.I get about 130 CFM! To really get this flow I've also learned that I'll have to be very carefull about duct size and the number of bends or I'll need a very large fan. So much for a couple of muffing fans from digikey!!

Does the 15 degree rise sound safe? Our house is air conditioned so ambient temp should never be above 80 or so.

I'm going to put 2 thermostats in the box located so the outlet air passes over them. The first will turn on the fans if the temp gets to about 77 degrees. The second will activate the IR command to shut the unit off if the box gets to 95 degrees. This way the emergency shutdown will still leave the fans on to cool everything down. This second one can also warn with an voice message through our home automation system. I'm worried about melting my new projector!

If I'm right about this I hope it can help others. If I'm not someone please set me straight!

A question for d-ila owners. Does the unit have a definite air flow path from left to right or from right to left. Does it just kinda spew air? This will help to optimize the design.

Many Thanks!

John Chapman



[This message has been edited by anderdea (edited 05-08-2001).]


[This message has been edited by anderdea (edited 05-08-2001).]


[This message has been edited by anderdea (edited 05-08-2001).]
 

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Randy,


I would recommend that you try and keep the projector below 90F and using the supplied formula with an ambient temp no more than 80F, you should be fine with about 200CFM net flow.


All hot air exits from one side of the projector, right side, looking at it from the front, table top. Air inlet is in two places...primarily on the bottom through the air filter grill and some around the lens opening. Be sure and baffle your box so that the hot air does not have an easy way to recirculate into the air inlet of the projector.


As others have mentioned, thermal sensors or cutoffs would be a good idea as a protective measure. Also, Radio Shack has some handy remote probe electronic thermometers that are handy for verifying that everything is working as planned.


Regards,


------------------

Tom Stites

Director, Business Development

Digital Systems Division

JVC Professional Products

"My opinions do not necessarily reflect..."
 

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ssands,


The cooling requirements of a G11 are exactly the same as a

G15. They both use the same lamp. The G15 gets its extra

500 lumens via an extra polarizer that scavenges light that

the G11 throws away. In that sense, the cooling requirement

of a G11 is actually the energy equivalent of 500 lumens

worth of photons greater than the G15 - but that's not much.


[ You have an extra 500 lumens of light going to the screen -

the energy of which will dissipate in the room, instead of

in the projector. ]


Greg
 

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"I would recommend that you try and keep the projector below 90F and using the supplied formula with an ambient temp no more than 80F, you should be fine with about 200CFM net flow."


Tom: Where are you measuring the projector temperature (i.e., the 90F)? Since the manual says that the ambient air temp should not exceed 95 degrees, I'm assuming that you measure at the air intake?


I believe the exhaust side air temperature runs anywhere from around 105 - 110 degrees, depending on ambient air and exhaust clearances. Is there a corresponding number as to how hot is too hot for the exhaust side? Since the projector has an internal temp cutoff switch, I assume that there is a sensor which checks the exhaust side temperature - what temp generates a shut off signal?


Thanks,


Marcel
 

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Quote:
Originally posted by Marcel J. Dumeny
"I would recommend that you try and keep the projector below 90F and using the supplied formula with an ambient temp no more than 80F, you should be fine with about 200CFM net flow."


Tom: Where are you measuring the projector temperature (i.e., the 90F)? Since the manual says that the ambient air temp should not exceed 95 degrees, I'm assuming that you measure at the air intake?


I believe the exhaust side air temperature runs anywhere from around 105 - 110 degrees, depending on ambient air and exhaust clearances. Is there a corresponding number as to how hot is too hot for the exhaust side? Since the projector has an internal temp cutoff switch, I assume that there is a sensor which checks the exhaust side temperature - what temp generates a shut off signal?


Thanks,


Marcel
Marcel,


The D-ILA does have an internal temp cutoff - but I wouldn't size my cooling system based on that.


In another thread, Tom Stites states that "heat is the enemy for all things D-ILA".


If you have a marginal cooling system, you might not trip the temperature cutoff, and you might not

fail the projector right away - but why subject it to any more thermal stress than you have to?


It seems lots of people are trying to find the minimum cooling capacity that they can "get away

with". When it comes to cooling - that's just plain poor engineering practice.


I would accept Tom's recommendation of at least 200 cfm - and run with that. You can get cooling

fans with that capacity. Personally, I went with a "Radon fan" - fans that are used to exhaust

naturally occuring Radon, a radioactive gas; in areas that have trouble with that.


These fans are available from such companies as Infiltec, Fantech, and Deflecto; they are very

quiet, and come in sizes that can easily supply the 200 cfm cooling requirements of a D-ILA.


You can find them online - or at a "Home Depot".


Greg
 

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Greg:


I have a fairly elaborate cooling system for my hushboxes for my two D-ila projectors, with duct work and in line fans on both inflow and outflow, and with a partitioned hushbox with a hot (air flow out) side and a cool (air flow in) side. But I do not have 200 cfm capacity fans currently (early posts on this subject on the forum talked about a single fan of 80cfm being more than satisfactory). Additionally, I have RF temperature guages, with audible warning presets, and a separate high temperature module which, when activated, turns on strobe lights, plus automatic load sensing swithces which turn on the fans when the projector is activated and turn off the fans when the projectors are off. My fan flow is less than 200 cfm, however.


My question is to get info to make decisions on how to set my temperature warning sensors and to eveluate my temperature data as against other peoples' temperature data and the internal projector settings. When I have the info I can then make better decisions on increasing fan capacity, etc. I do not intend to "skimp" on the air cooling system - I gave up on that a lot of dollars ago!


Marcel
 
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