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Discussion Starter · #1 ·
My theater was rather warm the other day so at the end of a movie I decided to get the flashlight out and check the exhaust temperature of my G-15 DILA. It's in a hush box with three 4" fans blowing into it.


To my shock the exhaust read 150 degrees. Is this safe? What is the max supposed to be? The DILA did not shut down with a temperature alarm and it's worked great since but I am worried that perhaps I should be checking the temperature whenever the room feels warm.


Does anyone know what the exhaust temperature should be under normal operation, (assume 85 degrees input air).


TIA,

Phil
 

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Phil,


I am going to have to assume that the temperature you gave is Fahrenheit, not Centigrade... So you're measuring 65 C, which is pretty normal. I'll have to dig in my notes, but I'm sure I measure temperatures in this range at the hottest spot in the fan exhaust.


William
 

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Phil


As you recall we've gone around on this point a few times and we often refer to the info from Tom Stites.

When I was first using my G15 in free space I noticed that the rear of the case next to where the hot air exhausts would be quite warm to the touch. Since this was normal operating conditions I can only assume I was experiencing temperatures similar to yours.

Since I built my hushbox I installed a fantec inline fan and built a plenum that attaches to the exhaust side of my G15, a radio shack temperature probe inside the plenum at the exhaust port never registers above 88 degrees F. The air is ducted to the exterior thru a side wall and the hushbox internal temperature is generally at room temperature. The rear of the case next to the exhaust port also stays at room temperature.

I really feel that the plenum is the key. Its simple to construct and it hangs on the upturned legs of the projector

I could try to get some pictures up but you're also welcome to come by next time you're in the area.

I hope this helps.

Rick
 

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as a poijnt of comparison, i put the digital thermometer on my zenith 1080 stb, known to run very hot...115 degreees F, well stabilized.
 

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Quote:
Originally posted by rick e


Since I built my hushbox I installed a fantec inline fan and built a plenum that attaches to the exhaust side of my G15, a radio shack temperature probe inside the plenum at the exhaust port never registers above 88 degrees F. The air is ducted to the exterior thru a side wall and the hushbox internal temperature is generally at room temperature. The rear of the case next to the exhaust port also stays at room temperature.
Rick,


Good to see someone else is also using an inline fan. Which Fantech fan do you use? What's the CFM rating. My inline

fan is an "Infiltec" - Fantech's chief competitor.


In addition to the fan - the exhaust is ducted - but I haven't instrumented the system as you have. I probably

should now that the Bay Area is heating up. What thermometer are you using?


Dr. Gregory Greenman

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Morbius


Thinking that there might be some inquiring minds out there I thought I might as well give you a few of the details.

Here's the performance data on the fantech 4XL. I would actually recommend the FR series over the FX that I bought. I think the resin housing of the FS series may be slightly quieter and I don't think the loss of CFM will be missed.
http://www.fantech.net/fx2.htm

I built a 3/4" cherrywood veneer hushbox and had it professionally sprayed with catalyzed lacquer. I then mounted it behind a support beam and shot the image thru a panamorph and then edmund optical glass after which the image lands upon a 96" wide Grayhawk. The entire rear of the box folds open on Salice euro cup type hinges for acess.

I wasn't satisified with the professional mount I had bought so I then came up with a mounting setup that used 4 turnbuckels mounted in the hushbox that allows me to position the projector perfectly.

I use a 6"powered duct that is plugged into the trusty craftsman auto sensing switch as is the fantech fan and the projector, so when the projector is remotely turned on the duct opens allowing outside air to be introduced into the general atmosphere of the hushbox. The 6" opening of the duct is covered in electrostatic filter material from home depot..

This is the powered duct I used
http://www.smarthome.com/cgi-bin/Search.exe?stock

The fantech inline fan is suspended inside the hushbox by a bungee cord to isolate it from the house and box. It is connected to the projector by several feet of insulated 4" flexible ducting which then connects to a plenum that hangs on the exhaust side of the projector hooked onto the projectors upturned legs. This plenum captures all the hot exhaust and directs it to the house's exterior.

The temperature sensor is a Rat Shack version with a remote "outside"probe that I place in the plenum. It reads inside/outside, high/low and %humidity.

With this setup and room temperature at 72 degrees the hushbox ambient registers 72 degrees as well and the probe at the exhaust port never reads above 90.

Note: I recently changed to the cermax 500 watt zenon and the temp reads 90. Before the stock bulb never gave an exhaust reading above 88 degrees F.

This is the Cable I'm using. Its a RG11. Belden 7731A . I constructed 60' of RGBHV terminated in some rather beefy BNC's. just typ 7731A in the search box.
http://bwccat.belden.com/cgi-bin/nco...mes.d2w/report

The HDTV and HTPC are switched thru a extron crosspoint 12x8 matrix switcher, I love that switcher!.

I also used this lead foam sandwich material to deaden the hushbox.

This is the insulating material used to line my homemade hushbox. It's called xtreme liner.
http://www.dynamat.com/

Anyway thats just a few of the details.

Of course everthing i've built I either learned from or was inspired by the forum.
 

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Discussion Starter · #7 ·
WM,


Thanks, that helps me sleep a lot better!


Rick E,


I am talking about the temperature right at the G15 4" exhaust grille. It sounds like you are talking about the general exhaust temp of the box.


Does anyone know what the actual JVC exhaust design specs of the G15 are?


Thanks,

Phil
 

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Phil


I'm measuring the exhaust temp right at the 4" exhaust port.

With the stock bulb the temp stayed at 88 degrees F

With the new cermax bulb the exhaust temp stays at 90 degrees.

The temp in the hushbox generally is at 72 degrees unless it is unusually hot or cold outside.

These temps are taken using a fantech 4" inline fan forced negative pressure system.

The temp probe is placed right against the exhaust port.

I'm moving a lot of air thru the G15.


Whats really nice is that the hot spot that use to be at the rear of the G15 case while running in free air is completly gone.


I'll have to get some pics up.


Rick


ps The fantech fan moves more air out of the system than the G15 fans produce. I put a little smoke at the edges of the plenum and there's negative pressure in the system so all the hot exhaust gets moved out.
 

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Phil:


My hushboxes for my two G-11 projectors have "cold" sides (with 92 cfm fans bringing room temperature air in) and "hot" sides (with 92 cfm fans moving air to the outside of the house). In between the two sides is a rubber diaphragm (cut up truck floor mat) keeping the air from circulating from one side to the other, except though the projector. See the picture at the Yahoo site after my signature for a picture of my one hushbox, showing the diaphragm.


I measure the temperatures on both the "cool" sides and the "hot" sides. The measurement on the hot side is about 6 inches from the exhaust.


Maximum temperature ever achieved in eight months of use on the hot side of my "small" hushbox in my master bedroom setup (hushbox is about 3.5 feet wide by 1.6 feet high by 2 feet deep, with a 6 inch wide "hot" side) is 116.1 degrees F. Maximum temperature ever achieved in eight months of use on the hot side of my "large" hushbox in my dedicated home theater setup shown in the pictures (hushbox is about 3.5 feet wide by 3.8 feet high by 2.5 feet deep, with a 9 inch wide "hot" side) is 112.6 degrees F. The "cool" side of my "small" hushbox typically runs about 80 degrees (with a room temperature of about 74 degrees), and the cool side of my "large" hushbox typically runs about 77 degrees (71 degree room temperature).


Hope this is of some use.


Marcel J. Dumeny
 

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Discussion Starter · #10 ·
Rick,


Wow!, those numbers seem almost too good to be true. You must really be dragging some serious air through that poor projector. Do the sides go concave when the fan kicks in? :D


Is that in line fan quiet? I may want to switch to it. Can you see any reason why it wouldn't work in a positive pressure, (source), mode?


Marcel,


Those numbers seem to be more in concurence with what I am seeing. The unit seems to be fine but if I remember correctly, every 10 degress C of temperature reduction will double reliability. That being the case, it is always a good thing to keep temperatures low.


Thanks,

Phil
 

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Phil


The temp in the plenum attached to the projector was measured by simply placing the probe within the plenum next to the exhaust. This of course isn't accurately measuring the temperature inside the projector. The negative pressure inside the plenum sucks a little air from around the plenum edges into the plenum lowering the exhaust air temperature, i.e. the projector fan cfm is lower than the fantech inline 175cfm 4" fan and the fantech can empty the plenum air volume faster than the projector can fill it. This increased air flow is obviously lowering the internal temperature but I'm not sure by how much. To check the exit exhaust temp better I pushed the probe thru the plastic case exhaust guard right up to the metal grill in front of the fan blades (I would think that removing these two grills would reduce the air turbulence and quiet the fan noise some but void my warrenty). At this location I measured a temperature of 47 degrees F above ambient. When it was 70 degrees in the hushbox the probe would measure about 117 degrees F just inside the projector case.


The thing that pleases me most is that the hot spot on the back of the projector case next to the exhaust port is completely gone, the case at this spot is at room temperature, even after hours of movie watching.


As far as he inline fantech being quiet is concerned I would recommend the other version of the same fantech fan. The 4" resin case as opposed to the 4" metal case I have should be quieter. It moves 125 CFM instead of the 175 mine moves but the negative pressure in my plenum indicates that a lower CFM may still move enough air, YMMV.


I don't know what the normal internal operating temperature for the G-15 is, and I haven't tried to measure since it would require me to allow the internal temperature to rise and as we all know heat is the enemy.


Rick
 

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Discussion Starter · #12 ·
Rick,


I remebered someone mentioning Nutone and did a search and found someone who had the exact same situation as you. The projector stabilized at 150F in open air then went to 114F in the hushbox with the Nutone attached. I guess I'll have to give this a shot. It should really help reliability.


Thanks,

Phil
 

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Wow, that's impressive. I've got a G1000 clone projector, and it measures as follows:


140-150F in free air at big exhaust, no hushbox or enclosure. Ambient temperature 75-80 degrees


162F in hushbox with front open wide, no fan forcing air. Ambient hushbox temperature measured near intake 82 degrees.


170F in hushbox enclosed, with 70CFM rated panasonic whisperwall fan forcing air through the exhaust. Ambient hushbox temperature measured near intake 88 degrees.


The ambient temperatures are measured with a probe near the back top of the ceiling mounted hushbox, closer to the exhaust side than the fan side. The exhaust temperatures are measured 1.5" from the exhaust, in the middle of a little 1.5" "tunnel" that ducts the air out of the hushbox.


I am surprised that anyone has gotten the temps down to 114F; that is amazing! I do think that the older G1000 projectors probably do generally run hotter, since the optics aren't as efficient, which means more light gets converted to heat rather than passing out, but I wouldn't think the difference would be that great.


I think I'll have to look a little more into plugging potential leaks in my hushbox and maybe adding another fan.


-Tom
 

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what would be more valuable to know is at what temperature the thermal breaker is triggered. Obviously this is where the engineers of the projector think it should be cut off before causing any damage.
 

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Hi, Bro!


A supercomputer researcher I've spoken with suggests a general rule of thumb for computing: a 10 degree C (18 degrees F) rise in temperature is roughly equivalent to halving the Mean Time Between Failures (MTBF).


Tryg: The breaker is set FAR too high to be a useful guide - you would never want to run your projector anywhere near its normal trip point!


Cool is GOOD!


Cheers!

MarkF
 
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