How can I keep a receiver cool?

March 31, 2008 4:33 PM

We've got an Onkyo receiver for our new home theater that is running really hot....how can I best place a fan to maximize cooling?

My father recently purchased a entertainment center to house all of his electrical components for an awesome new tv/surround sound/etc setup….the tv sits right in the center of the entertainment center and there are two cabinets below for the receiver, dvd player, ps3, etc….the cabinets have glass-paned fronts and he has cut holes in the back to allow for air-flow, however, the Onkyo receiver that he purchased seems to run really, really hot…to try and solve the problem, he purchased a large PC fan and rigged it to sit almost directly on top of the receiver (about a finger or two of space away from the top of the thing), blowing cool air down into the air vents…sorry for all the lead up, but here’s my question….is this the most effective use of the fan? Would the fan be more effective blowing warm air out than cool air in? What if he tilted the fan on its side instead to blow cool air in on top of the vents as opposed to inside of the machine itself it….basically, we’re just trying to figure out optimal fan placement for best cooling in a confined space….thank you!


Oh, and I read up on all of the previous questions regarding this topic and there was actually one that was really similar; however, the responses never really answered the question…so that’s why this is here…

posted by Hogermite to technology (5 comments total)

It isn't actually clear from your question, but if the space is enclosed behind doors, the best thing to do would be to install two fans, one blowing in and the other blowing out.

Put the "out" fan at the top of the enclosed area, and the "in" at the bottom. The fact that it runs hot isn't itself a problem, but you do need to ensure that the surrounding area doesn't also heat up. What I mean is, they've already figured out the airflow issue, don't worry about that - just don't set anything on top of it. Use your fans to cool the entire enclosed area by removing the heat it produces and replacing it with cool air from the floor.
posted by odinsdream at 4:39 PM on March 31, 2008

blowing cool air down into the air vents

is going to completely screw up the convection-driven airflow that is supposed to be keeping the receiver cool.

You will find that equipment designed to work on an open shelf will be unhappy in a closed cabinet unless there's an easy way for hot air to escape. So, put your fan in a hole as high up the back of the cabinet as you can, oriented to suck hot air out. Don't create weird air currents inside the cabinet that mess with the way the cooling airflow is designed to work inside the individual equipment casings.
posted by flabdablet at 5:25 PM on March 31, 2008

you will create more noise if you use more than one fan. Technically each fan will move the same amount .. so if you put two, one in, one out, you will have only a small amount more air flow then if you were to use both fans for a common task (i.e. both out)

My suggestions that have been proven through practice:

Put the fan(s) on the TOP of the enclosure's back wall, with a hole that lets the fan(s) blow out the hot air.

Make sure you have the same size (or slightly larger) vents on the BOTTOM of the back-wall of the enclosure for cool air to rush in. If you want to get really efficient, cut a few holes in the shelf underneath each device to be cooled, so cool air can rush in, go through the holes, through the vent holes in the case of the device, taking the heat with it while it gets pulled out by the fan at the very top (remember: heat rises).



The practice ... I have made a 5 foot long cardboard sound-insulated "duct/chimney" for the hot air "out" port on the back of my computer desk. This duct attaches right where the fan blows out the hot air from the case, and extends up the back of the desk to the very top.

I am using a 180mm (huge) PC fan with a thermistor ... which will vary its speed based on how hot the air is moving past it. Most of the time, the heat pulls itself up the chimeny and out of the area, while cool air replaces it at the very bottom where I have my in-ports.

When the servers I am cooling get hotter (they are twin pentium 4's a.k.a portable heater's) the fan speeds up moving much more air and only becoming slightly louder. I figured out I didn't need a full 12 volts and rigged it for 7 volts from the PSU .. so when the pc turns off so do the fans!

I would suggest a smart strip for automatic on-off switching of your fan(s) (and other devices to save energy, if you want).

The only problem I have now .. is reminding myself to clean out the enclosure. All the air that moves past the PC lets the dust accumulate VERY fast.
posted by Ryaske at 5:33 PM on March 31, 2008

If the receiver isn't shutting off when it's hot, then it is operating within what Onkyo deems to be acceptable temperatures. All modern receivers have thermal protective circuitry. Naturally, cooler is better, and the easiest fix for that is to simply turn that fan over so it draws warm air out. Cooler air will move in from the other vents replace it.
posted by pmbuko at 8:16 PM on March 31, 2008

I had the same issue when I set up my home theatre. The best thing I did was just to remove the doors from the cabinets.

Nice and cool now.
posted by WinnipegDragon at 9:04 PM on March 31, 2008