Question About Convection Cooling Of A Specific Power Supply Unit

Thread Starter

PGB1

Joined Jan 15, 2013
117
Good Day All!
Hopefully, I put this question in the proper section of the forum. Pardon me & feel free to move it if I goofed.

I have a 120 volt AC input power supply unit (PSU) which will provide 12 VDC outputrated for a maximum of 36 watts. The actual load will be 24 watts. The device to be powered is a strip of LEDs that come in a spool.
The 2 solid sides of the case are aluminum. The perforated faces are steel.

When I ask my question below, I mention 'Side 1' 'Side 2", etc. There is a photo with the sides named. Hopefully it will remove some confusion of what I'm trying to explain.

The PSU will be mounted to the vertical face of a floor joist in the basement. The joist will remain open to the floor. (No ceiling). At the top of the joist is the sub floor above. There will be spacers behind the PSU to leave a gap between it and the joist face.

Inside, there are two components mounted to heat sinks in a fashion I've never seen before. The components are vertical. There is one aluminum bar crossing the front of both. There is a screw that enters the bar between the components and clamps the components to the case wall (Called 'Side 1' in the photos. It's the face with the label.)

My question is: What is the best orientation for this unit for optimum convection cooling? There will be no fan forced cooling.

I studied around and learned that having the circuit board flat (parallel to the floor) is not a good idea, so I won't mount it upside down on the bottom of the sub floor. (Unless you all tell me that's the best plan.)

Referring to the photos, my guess is that I should mount this with Side 3 facing up. (Second to last photo) Air will (??) enter side 2 and exit Side 3.

Next guess was Side 1 faces up (last photo). Air enters Side 3 (facing the ground) and exits the large face of side 2. But will heat get trapped against Side 1, the one acting like a heatsink?

Thanks Very Much For Your Suggestions!
I appreciate your advice.
Paul
PaulA Main View of PSU.JPG Sides Of PSU Combined.jpg
B Guess 1.JPG
C Guess 2.JPG
 

wayneh

Joined Sep 9, 2010
16,399
I don't know the answer to your question, but just want to throw out there for you that a $5 computer case fan could render the question moot. These things draw less than 100mA and the forced air would eliminate any convection concerns. You would orient the fan to blow into a perforated side.
 

Thread Starter

PGB1

Joined Jan 15, 2013
117
Thank You Wayneh,
That's something to consider if I am not satisfied by natural convection. I suppose this project calls for some experimentation (always fun, if nothing else).
Enjoy Today!
Paul
 

Kermit2

Joined Feb 5, 2010
4,162
your next to last picture is the proper orientation.
operating the supply at less the max you shouldnt have any problem with overheating.
 

wayneh

Joined Sep 9, 2010
16,399
I agree with Kermit. A 24W load should not produce 24W in the PSU, and I wouldn't fear mounting a 24W bulb inside that box oriented that way.
 

Thread Starter

PGB1

Joined Jan 15, 2013
117
Thank You All for your help & ideas! I very much appreciate the guidance.

I re-read my post and see that I didn't explain very well at all. (Like usual)
The lights are actually going to be away from the box. I won't be putting any inside, although there is one LED on the terminal strip.

So, I'll orient it as per the second to last photo.

Thanks Again All!
Paul
 
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