Is there any reason why more people don’t mount their fans in the top of the projector; as hot air rises I would have thought it was the more logical place to put an extractor fan for the heat source; although I admit I have probably overlooked something 🙂
Anyway, here is my plan, please let me know if you think it will work out ok!
My projector is a straight through projector; no mirrors, and is based around an 8" hami.
I have constructed a light box out of aluminum, and before the light leaves this box it goes through some UV/IR filtering glass. I am thinking of removing 120mm out the top of my aluminum light enclosure, to allow air flow, and then in the light/ballast compartment mounting a 120mm 105cfm fan in the roof of the projector enclosure. To ensure sufficient airflow to feed the fan, I am going to put an 80mm grill just behind the fresnel/lcd mount (on the light side) on each side (left and right) of the enclosure. This will then mean the air should flow in these, across the fresnels (and lcd) and across to the 120mm fan and out. As the 120mm will be sitting across the top of the light box (which is only 60mm deep, so will leave some of the fan in the main projector) very little heat should be allowed to escape form the light into the main enclosure anyway.
On the projection side of the box I will have a grill in one side and a relatively small 80mm (quite) fan pulling air out opposite it. Really, not much heat should reach this part but this will ensure that the LCD gets regular air flowing across it, preventing it getting too hot.
So does this sound ok; I am struggling with a diagram as I don’t know where to host it!
Do you thing a 120mm fan will let in too much light (or the grills?) I will cover them all with a black mesh to cut down the light lost. I know this will also cut down on the amount of air, but I figure to 105cfm fan should shift enough anyway, and if this doesn’t work I can use a 125cfm (or even higher).
Please let me know any comments as I am not too good at diy and what to get this right first time if I can.
Thanks for any help,
Matt
Anyway, here is my plan, please let me know if you think it will work out ok!
My projector is a straight through projector; no mirrors, and is based around an 8" hami.
I have constructed a light box out of aluminum, and before the light leaves this box it goes through some UV/IR filtering glass. I am thinking of removing 120mm out the top of my aluminum light enclosure, to allow air flow, and then in the light/ballast compartment mounting a 120mm 105cfm fan in the roof of the projector enclosure. To ensure sufficient airflow to feed the fan, I am going to put an 80mm grill just behind the fresnel/lcd mount (on the light side) on each side (left and right) of the enclosure. This will then mean the air should flow in these, across the fresnels (and lcd) and across to the 120mm fan and out. As the 120mm will be sitting across the top of the light box (which is only 60mm deep, so will leave some of the fan in the main projector) very little heat should be allowed to escape form the light into the main enclosure anyway.
On the projection side of the box I will have a grill in one side and a relatively small 80mm (quite) fan pulling air out opposite it. Really, not much heat should reach this part but this will ensure that the LCD gets regular air flowing across it, preventing it getting too hot.
So does this sound ok; I am struggling with a diagram as I don’t know where to host it!
Do you thing a 120mm fan will let in too much light (or the grills?) I will cover them all with a black mesh to cut down the light lost. I know this will also cut down on the amount of air, but I figure to 105cfm fan should shift enough anyway, and if this doesn’t work I can use a 125cfm (or even higher).
Please let me know any comments as I am not too good at diy and what to get this right first time if I can.
Thanks for any help,
Matt
Allo mate!
Hello mate, I may strive to provide some information for you in regards to the cooling of your projector.
I must say that a very important heat blocking component of your projector will be the IR (low-E) glass. Not the UV panel but the IR panel. We're all aware that the hot air coming off the top of an open flame is rather hot. Now if you place a finger besides the flame you can still detect heat but not as much. This is infrared radiation of the flame. Next time it's bonfire night in the UK and your face is all warm from the fire try using a piece of cardboard and put it in front of your face. You can feel a cooler result of this as the cardboard is now blocking the IR radiation.
Yes it is wise to place the exhaust fan at the top of the box as you say because the heat rises. But we can somewhat get around this because we're no just dealing with passive airflow here. Our fans pump out about 33 - 100 cubic feet per minute and that's a lot in consideration to the size of a projector or computer box that they're originally designed for.
You mention putting a inlet grill on the side to cool the LCD and fresnels first. Would it be possible to place the inlet on the bottom? There it would have the ideal cooler air at the bottom, hot air out of the top. You could use shallow foot pieces that allow the projector to sit about 1/2" off the table top. Air would enter from the underside of the box and move up. This method may also help the issue of light leakage.
I'm about 80% done with the construction of my projector and I designed it so that the air enters at the front, snakes twice past the LCD and then onto the light source (which has it's own fan) and then out the back. The "pooling" of hot at at the top of the box doesn't bother me too much because the exhaust fan is doing a good job at constantly drawing in fresh cool air. It would be cool to know exactly how long it takes air to first enter the box and then exit but that's a little much for my needs. I've tested the box and the results are great. If you're interested in seeing some of my results online I've got them at my website, it's called the Tati Projector.
http://communities.msn.com/portraitsmore
Cheers mate and good luck! Let us know what you come up with and welcome to the forums. O.K. enough of my chinwag.
Chris B. in Iowa
Hello mate, I may strive to provide some information for you in regards to the cooling of your projector.
I must say that a very important heat blocking component of your projector will be the IR (low-E) glass. Not the UV panel but the IR panel. We're all aware that the hot air coming off the top of an open flame is rather hot. Now if you place a finger besides the flame you can still detect heat but not as much. This is infrared radiation of the flame. Next time it's bonfire night in the UK and your face is all warm from the fire try using a piece of cardboard and put it in front of your face. You can feel a cooler result of this as the cardboard is now blocking the IR radiation.
Yes it is wise to place the exhaust fan at the top of the box as you say because the heat rises. But we can somewhat get around this because we're no just dealing with passive airflow here. Our fans pump out about 33 - 100 cubic feet per minute and that's a lot in consideration to the size of a projector or computer box that they're originally designed for.
You mention putting a inlet grill on the side to cool the LCD and fresnels first. Would it be possible to place the inlet on the bottom? There it would have the ideal cooler air at the bottom, hot air out of the top. You could use shallow foot pieces that allow the projector to sit about 1/2" off the table top. Air would enter from the underside of the box and move up. This method may also help the issue of light leakage.
I'm about 80% done with the construction of my projector and I designed it so that the air enters at the front, snakes twice past the LCD and then onto the light source (which has it's own fan) and then out the back. The "pooling" of hot at at the top of the box doesn't bother me too much because the exhaust fan is doing a good job at constantly drawing in fresh cool air. It would be cool to know exactly how long it takes air to first enter the box and then exit but that's a little much for my needs. I've tested the box and the results are great. If you're interested in seeing some of my results online I've got them at my website, it's called the Tati Projector.
http://communities.msn.com/portraitsmore
Cheers mate and good luck! Let us know what you come up with and welcome to the forums. O.K. enough of my chinwag.
Chris B. in Iowa
Thanks for the reply.
Looking at your design it seems you have two fans; one to blow the heat from the light to the back of your projector and another exhaust fan to suck air out. I take it you have an inlet at the font to allow air in, which then takes its jouirney as shown?
Could you let me know the size and cfm of yuor exhaust fan please?
Thanks for your help, it is appreciated.
Matt
Looking at your design it seems you have two fans; one to blow the heat from the light to the back of your projector and another exhaust fan to suck air out. I take it you have an inlet at the font to allow air in, which then takes its jouirney as shown?
Could you let me know the size and cfm of yuor exhaust fan please?
Thanks for your help, it is appreciated.
Matt
Hello again Matt,
Yes the front of the projector has inlet holes to allow air inside. The air then snakes around the LCD in two passes to hopefully cool it down. After that the air reaches the first fan that's down near the bottom of the box blowing directly onto the light. That fan is a standard 80mm thin style fan I got from the Lumen Lab site. Does a pretty good job at keeping the bulb cool and that bulb's a 400 watt Halogen! It's rated at moving about 33 cubic feet per minute and the decibel level is stardardly quiet.
The second fan also from the Lumen lab and is the cylidrical design. I chose this one because it's rated at 33-100 cubic feet per minute and the sound maximum is that of the thin style fan. It does move the air well and both fans are relatively quiet together. I do plan on using some foam weatherstripping where the fans mount to the box as you can hear them inside and I worry that may be too noticeable. Kinda like how a wind up music player in a jewelry box works. When you place the player on a surface or box it greatly amplifies the sound but when held in the hand the sound is faint and tinny, hmmm.... that must be why Lumen sells neopryene mounting gaskets for the fans. Anyway if the sound is still too much off of the cylidrical fan I plan on installing another on top of it and turning both down to 50% (it's nice that they're dimmable). That'll give me the same airflow at half the speed per each fan. Plus I'll have a reserve for more airflow if needed.
Hope this info helps you out mate! and have a good weekend!
Cherrio,
(from a chap that briefly grew up on the Alconberry USAF base in the early 80's)
Chris B. in Iowa
Yes the front of the projector has inlet holes to allow air inside. The air then snakes around the LCD in two passes to hopefully cool it down. After that the air reaches the first fan that's down near the bottom of the box blowing directly onto the light. That fan is a standard 80mm thin style fan I got from the Lumen Lab site. Does a pretty good job at keeping the bulb cool and that bulb's a 400 watt Halogen! It's rated at moving about 33 cubic feet per minute and the decibel level is stardardly quiet.
The second fan also from the Lumen lab and is the cylidrical design. I chose this one because it's rated at 33-100 cubic feet per minute and the sound maximum is that of the thin style fan. It does move the air well and both fans are relatively quiet together. I do plan on using some foam weatherstripping where the fans mount to the box as you can hear them inside and I worry that may be too noticeable. Kinda like how a wind up music player in a jewelry box works. When you place the player on a surface or box it greatly amplifies the sound but when held in the hand the sound is faint and tinny, hmmm.... that must be why Lumen sells neopryene mounting gaskets for the fans. Anyway if the sound is still too much off of the cylidrical fan I plan on installing another on top of it and turning both down to 50% (it's nice that they're dimmable). That'll give me the same airflow at half the speed per each fan. Plus I'll have a reserve for more airflow if needed.
Hope this info helps you out mate! and have a good weekend!
Cherrio,
(from a chap that briefly grew up on the Alconberry USAF base in the early 80's)
Chris B. in Iowa
Hello Matt,
Yes I believe that's the one as I am familiar with the name Huntingdon. I was only a small Tom by the ages of 4-8 at the time (born 1976) but I do remember some of the places and the schools I went to (both on base and private). LOL quite fun to type back and forth with a chap that's right from that area!
I had a terrific weekend with the projector over the weekend as I added the needed support bars for the fresnels and placed the top of the machine on to make it use the presecribed ventilation routing. The ventilation worked great and I never developed a hot darkening spot on the LCD as I had before. I haven't even bought IR blocking glass yet and everything seems fine! I will purchase some of that glass just for added security but it was a treat to run the machine for about 1.25 hours. I even took some digital photos of it in action and will be posting some to my website soon.
I must say that I was worried about the one fan (100 cfm) at the back not providing enough airflow to cool things but after seeing how the LCD stayed cool without a IR blocker I think I'm onto a winner. The exhaust air out the back was indeed quite warm but that's exactly what one would expect. THe roof of the light engine compartment did become warmish but not to a worrysome or offensive level.
Do hope that this info helps you out in your design endeavors.
Chris
Yes I believe that's the one as I am familiar with the name Huntingdon. I was only a small Tom by the ages of 4-8 at the time (born 1976) but I do remember some of the places and the schools I went to (both on base and private). LOL quite fun to type back and forth with a chap that's right from that area!
I had a terrific weekend with the projector over the weekend as I added the needed support bars for the fresnels and placed the top of the machine on to make it use the presecribed ventilation routing. The ventilation worked great and I never developed a hot darkening spot on the LCD as I had before. I haven't even bought IR blocking glass yet and everything seems fine! I will purchase some of that glass just for added security but it was a treat to run the machine for about 1.25 hours. I even took some digital photos of it in action and will be posting some to my website soon.
I must say that I was worried about the one fan (100 cfm) at the back not providing enough airflow to cool things but after seeing how the LCD stayed cool without a IR blocker I think I'm onto a winner. The exhaust air out the back was indeed quite warm but that's exactly what one would expect. THe roof of the light engine compartment did become warmish but not to a worrysome or offensive level.
Do hope that this info helps you out in your design endeavors.
Chris
Hello! The only problem I've seen that venting off the top of the box creates is light leakage. When light leaks from the top of the box, it often hits the ceiling which lights the room up (the opposite effect you're going for). But here's a design I thought up (nothing someone who's worked on venting before hasn't seen) that could solve the light leakage problem.
Place the fan above the light bulb (sucking air FROM the bulb, not blowing air ON the bulb). Then place venting as shown in the picture to the top of the box. A light blocking grill at the end of the venting would be a good idea.
This way, heat is transported upward (heat's desired direction) and light is stopped at the elbow bends in the venting. Painting the inside of the vents flat black might help too. Good luck with the projector!
An externally hosted image should be here but it was not working when we last tested it.
Place the fan above the light bulb (sucking air FROM the bulb, not blowing air ON the bulb). Then place venting as shown in the picture to the top of the box. A light blocking grill at the end of the venting would be a good idea.
This way, heat is transported upward (heat's desired direction) and light is stopped at the elbow bends in the venting. Painting the inside of the vents flat black might help too. Good luck with the projector!
Sorry I haven't relied for a while, things got busy at work!
Finally got some stuff done on my projector. It is a straightforward design with no mirror, but is my first so wanted to keep it simple.
Got the lcd stripped and working - all secure now.
Got the holder for the lamp built and the holder for the lcd built.
Got the objective lens mounted.
Tried it out in a test run and, after I had got the fresnel the right way round everything looked good.
I now have 2 options for my fans
1) go with what I had before; a 120mm in the top above the bulb and a 80mm in the edge the other side of the LCD to pull fresh air across the lcd.
2) 1 80mm in the side before the lcd on the lamp side and a hole opposite and the same arangement on the other side of the lcd.
The 80mm fans will be 45cfm rated; does this sound like enough to you guys and gals and which arrangement for the fans would you suggest?
Once i have done the holes for this i can put the case togther and get everything safely inside, which will be a relief!
Gadgethead, saw your work over on DIYPC; looking good!
Cheers,
Matt
Finally got some stuff done on my projector. It is a straightforward design with no mirror, but is my first so wanted to keep it simple.
Got the lcd stripped and working - all secure now.
Got the holder for the lamp built and the holder for the lcd built.
Got the objective lens mounted.
Tried it out in a test run and, after I had got the fresnel the right way round everything looked good.
I now have 2 options for my fans
1) go with what I had before; a 120mm in the top above the bulb and a 80mm in the edge the other side of the LCD to pull fresh air across the lcd.
2) 1 80mm in the side before the lcd on the lamp side and a hole opposite and the same arangement on the other side of the lcd.
The 80mm fans will be 45cfm rated; does this sound like enough to you guys and gals and which arrangement for the fans would you suggest?
Once i have done the holes for this i can put the case togther and get everything safely inside, which will be a relief!
Gadgethead, saw your work over on DIYPC; looking good!
Cheers,
Matt
Allo Matt mate from across the pond!
Good to hear that you've made some progress on your PJ. I bet you were knackered after stripping the LCD. O.k. now onto the fan issue.
I tend to like your first option of using two fans, one top and one on the side. The top one will definetely vent out any hot rising air in your box and like the previous post by SuperDave you can built an offset/plate design to block the problem of a light leak. I really appeal to the 80mm that is mounted on the side to give first cooling priority to the LCD. I assume that you are also going to use a IR glass panel (and a UV filter is good too).
To give you some idea of the amount of airflow needed to keep the LCD cool I'll use my experience with the OHP halogen 400 watt bulb, a hot puppy by the way! At first I was really worried that I'd never be able to cool the LCD enough to prevent it from getting that all terrible hot spot that grows on the screen. The "pull thru" cooling design of my box uses just one of those clylindrical trubine type fans that are rated at moving 100 cfm when all the way up (it does make a slight whirring sound though). I knew that I wanted the first cooling priority to be given to the LCD. When I first tried this design out without a IR glass panel for the toasty 400 watt halogen and I was surprized! The LCD kept cool and never developed the overheating problem! The fresnels were even cool since they made up the other parts of the cooling channel that I put into the design.
http://groups.msn.com/portraitsmore/thebigprojectorproject.msnw?action=ShowPhoto&PhotoID=392
Before this test I thought that I may need to invest in another 100 cfm fan to put in the back of the PJ to increase my total airflow to 200 cfm but as of right now if it's not showing a problem I'm not going to change things.
In both of your design proposals you pretty much have a 80mm fan blowing on the LCD and that's great! I only worry that a box airflow of 45 cfm is a little low, but that's from my dealing with a hot halogen bulb. The metal halides I know are cooler. Perhaps in beam and hopefully in bulb temp. I'm waiting to save up for one of those nice puppies. You'll just have to try it out and see if 45 cfm works, but I'll say anticipate adding another fan into your design so leave a place that you can add it to.
I was having a bed fume problem emitting from my OHP bulb and I think that my heatsink that I made from aluminum was encasing it in it's own little "oven". I've since located a proper bulb holder (waiting for it to come) and learned that the dichroic reflector of those things need to be kept cool. It was doing my head in for weeks but help from a few likely lads pointed me to consider the heat condition of the bulb. What I had done inadvertantly was build the heatsink to make the bulb handelable, but not cool when operating. I hope that I've now got this under control and can enjoy watching movies. I'll be posting results to the DIY site.
We all look to your continued progress and good luck Matt!!
Cheerio,
Chris B. in Iowa
Good to hear that you've made some progress on your PJ. I bet you were knackered after stripping the LCD. O.k. now onto the fan issue.
I tend to like your first option of using two fans, one top and one on the side. The top one will definetely vent out any hot rising air in your box and like the previous post by SuperDave you can built an offset/plate design to block the problem of a light leak. I really appeal to the 80mm that is mounted on the side to give first cooling priority to the LCD. I assume that you are also going to use a IR glass panel (and a UV filter is good too).
To give you some idea of the amount of airflow needed to keep the LCD cool I'll use my experience with the OHP halogen 400 watt bulb, a hot puppy by the way! At first I was really worried that I'd never be able to cool the LCD enough to prevent it from getting that all terrible hot spot that grows on the screen. The "pull thru" cooling design of my box uses just one of those clylindrical trubine type fans that are rated at moving 100 cfm when all the way up (it does make a slight whirring sound though). I knew that I wanted the first cooling priority to be given to the LCD. When I first tried this design out without a IR glass panel for the toasty 400 watt halogen and I was surprized! The LCD kept cool and never developed the overheating problem! The fresnels were even cool since they made up the other parts of the cooling channel that I put into the design.
http://groups.msn.com/portraitsmore/thebigprojectorproject.msnw?action=ShowPhoto&PhotoID=392
Before this test I thought that I may need to invest in another 100 cfm fan to put in the back of the PJ to increase my total airflow to 200 cfm but as of right now if it's not showing a problem I'm not going to change things.
In both of your design proposals you pretty much have a 80mm fan blowing on the LCD and that's great! I only worry that a box airflow of 45 cfm is a little low, but that's from my dealing with a hot halogen bulb. The metal halides I know are cooler. Perhaps in beam and hopefully in bulb temp. I'm waiting to save up for one of those nice puppies. You'll just have to try it out and see if 45 cfm works, but I'll say anticipate adding another fan into your design so leave a place that you can add it to.
I was having a bed fume problem emitting from my OHP bulb and I think that my heatsink that I made from aluminum was encasing it in it's own little "oven". I've since located a proper bulb holder (waiting for it to come) and learned that the dichroic reflector of those things need to be kept cool. It was doing my head in for weeks but help from a few likely lads pointed me to consider the heat condition of the bulb. What I had done inadvertantly was build the heatsink to make the bulb handelable, but not cool when operating. I hope that I've now got this under control and can enjoy watching movies. I'll be posting results to the DIY site.
We all look to your continued progress and good luck Matt!!
Cheerio,
Chris B. in Iowa
Thanks for the response.
I have to keep my reflector cool as well. I am sort of hoping the big fan at the back might do this, but we will see 🙂
So my current plan is in the back compartment, above the bulb, put my 12cm 105cfm fan. On the other side of the LCD, towards the objective lens, I will mount a blowing 8cm 47cfm fan. This will blow cold air across the lcd and this will be pulled under and above the lcd, around the fresnel and out of the top. Hence hot air will not be allowed to mingle with the other air and I should get a flow around the LCD/Fresnels of nice cool air.
I have filter galss just infront of the lamp. It is IR/UV reflective so any light hitting the fresnel is already filtered. The tried and tested "holding a hand infront of it and seeing if it was hot" method told me that there was less heat infront of the lamp than above it so that was all good. My only slight concern is my reflector as this has no direct fan on it. I might put another 80mm acorss this to get it cooled before the air is sucked out, just to be safe.
Just finsihed my sliding rails for my LCD so it is held securing in place but can easily be removed for cleaning/replacing when required. My fresnel has a slight bow in it but a) it is not alot and did not seem to effect the uniform brighness of my test run and b) it is inwards towards the lcd holder so i can compensate for alot of it but putting in a frame around it of the right width.
I figure if anyhting is to be slightly wrong I am damned lucky that it is the fresenel as that is by far the cheapest part of the projector 🙂
Take care of yourself,
Matt
I have to keep my reflector cool as well. I am sort of hoping the big fan at the back might do this, but we will see 🙂
So my current plan is in the back compartment, above the bulb, put my 12cm 105cfm fan. On the other side of the LCD, towards the objective lens, I will mount a blowing 8cm 47cfm fan. This will blow cold air across the lcd and this will be pulled under and above the lcd, around the fresnel and out of the top. Hence hot air will not be allowed to mingle with the other air and I should get a flow around the LCD/Fresnels of nice cool air.
I have filter galss just infront of the lamp. It is IR/UV reflective so any light hitting the fresnel is already filtered. The tried and tested "holding a hand infront of it and seeing if it was hot" method told me that there was less heat infront of the lamp than above it so that was all good. My only slight concern is my reflector as this has no direct fan on it. I might put another 80mm acorss this to get it cooled before the air is sucked out, just to be safe.
Just finsihed my sliding rails for my LCD so it is held securing in place but can easily be removed for cleaning/replacing when required. My fresnel has a slight bow in it but a) it is not alot and did not seem to effect the uniform brighness of my test run and b) it is inwards towards the lcd holder so i can compensate for alot of it but putting in a frame around it of the right width.
I figure if anyhting is to be slightly wrong I am damned lucky that it is the fresenel as that is by far the cheapest part of the projector 🙂
Take care of yourself,
Matt
Spot on Matt! Sounds like a great start to your setup. We all look forward to seeing how things turn out for you. Bonus will be to see actual photos of your project too. (If you happen to need help with posting photos on a forum just let me know).
Chris B. in Iowa 😎
Chris B. in Iowa 😎
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