How much air space is required above my receiver?

[darlinsk]

I just set up my new receiver, a Denon 2807, in one of those home theater tables with glass shelves, open on all sides. I bought it before I purchased the receiver. The 2807 is fairly large, and after fiddling with the shelves, the most I could eek out is about 3" headroom above the receiver.

The Denon manual is hopeless. It has a caution saying: "For best heat dispersal, do not install this unit in a confined space such as a bookcase or similar enclosure." It even provides a little diagram with arrows above and to the side of the receiver. But where you would expect to see numbers representing the minimum space requirements, it has asterisks! Send that technical writer back to school!

It seems hot. The glass shelf above it is warm. So I stuck a digital thermometer between the glass and the receiver (above the receiver where the heat vents are) and got a reading of 111 degrees.

Do I have a problem? Any thoughts on remediation other than a new stand or a new receiver? I have other constraints in that room ... like a knee wall with a sloped ceiling, so I really can't have a table much higher than the one I purchased.

 

[Adam]

Three inches isn't too shabby. I'm assuming that your temperature measurement of 111 was in Fahrenheit, and that's not overly hot. If the unit isn't shutting off on you, I wouldn't worry about it.

 

[darlinsk]

Yes, farenheit. I would have 3rd degree burns if it were celsius. ;-) So, if I'm understanding you correctly, the unit will turn itself off if it overheats. So I can assume if it keeps on working, then all is OK? That's very helpful; thank you. Now I can agonize over speaker placement.

 

[Adam]

I don't know for sure if that unit has a thermal protection system, but the receivers with which I'm familiar do (and they aren't any more expensive than that Denon). The owners manual might mention it somewhere.

The fact that you have it open to air flow from all sides is a good thing. You'll get some heat build-up because you have a surface directly above the receiver, but I'll bet that most people who own that receiver probably have it in a more constrained space. My Pioneer (and Yamaha before it) is in an enclosed cabinet with about three inches on top, but only about an inch on either side. Mass market gear like ours is designed for mass market people, and a lot of those people are putting them into enclosed areas with doors on the front ("honey, I don't want to have to look at that all of the time!"), so you should be just fine.

 

[MDS]

As a frame of reference, Onkyo manuals for the larger receivers like the 805 and 875 suggest 8" above, 4" on each side, and 4" at the rear. I don't know anyone that has that much clearance.

When I had my wall unit built, I tried to split the difference and make the top area 11" tall and 20" wide, figuring that would leave 4" for airflow above and roughly 2" on each side. The problem is that it doesn't look that great IMO because all of the other components are tiny (a typical DVD player is 3" tall). So you have one shelf almost fully occupied by the receiver and the other shelves look barren with way too much space above the dvd player, cable box, etc.

I now think 8.5-9" is sufficient (leaving 2" above) as long as there is adequate ventilation otherwise - like cutouts in the back or open in the front. I've never really had an issue with receivers overheating or shutting down but they will get quite warm if played loud for long periods of time.

 

[hemiram]

Well, my Yamaha RX-V659 receiver has (approx) 4 feet above it, 2 feet on one side, and about 9 feet on the other. There are advantages of having it on top of the rack!

3 inches is probably ok, with the sides and back open, there should be enough airflow around it. Was the 111 degrees measured when it was idling, or was during or right after you played a movie at high level? You got me curious, and I took my temp gun out, and my 659 runs about 86 at idle, and about 120 at pain level. That's just pointing it at the top of the grill in the top rear. It jumps around quite a bit. Basically, if you can touch it as long as you want to, it's ok. If it's touchable, but only for a few seconds, it's borderline. And if it sizzles, well, that's too hot!

You can always put a couple of those little fans in the shelves to blow air around, if you get good ones, and don't run them full speed, they are very quiet. I've had to do this a few times due to cramped shelves. One decent sized one is usually enough. I had one on each side of the receiver I used for my PC audio playback, one pulled air in from the left, and the right one pushed it out. Dropped the temp almost 40 degrees. Even then, it wasn't pleasant touching the heat sinks if you had it turned up. It lasted for almost 20 years, so I guess it was ok. Main filter caps shorted and exploded one day, and it smoked the PC board to the point it wasn't worth fixing.

 

[mike c]

i'd stick with 4" on top at least ... that would give you space to at least put one of those 80mm PC fans blowing across the top if the other sides are enclosed.