22 September 2012

My Entertainment Cabinet Cooling Project

Since 2010, we've had a new entertainment cabinet and TV stand that we bought at Costco that has housed all our media equipment. It is a pretty nice wood cabinet, with 2 cabinets on either side, each with a slide-out shelf in the middle. The doors to each cabinet have replaceable panels, which we decided to have glass put in them. It fit our needs extremely well, but had one large downside: the back panels for each of the cabinets only had holes for the wires to go through and, thus, did not provide enough ventilation.
Now, for some time this wasn't such a problem but as we began to upgrade and get new equipment like a DVR and Logitech Revue Google TV unit, these always-on units produced a lot of heat, and so closing the doors wasn't an option. Closing the doors only trapped the heat in the cabinets, and it got so hot in the cabinets that you could feel the heat from inside the cabinet on the top of the cabinet. For over a year, we just kept the doors open, occasionally pointing small fans into the cabinets when it got particularly warm. But I was never satisfied with this "fix" as it looked messy, so I resolved to come up with a cost-effective solution.
At first, I wanted to go all-out and buy 4 PC case fans controlled by an Arduino which could monitor temperatures in each of the cabinet sections and independently control the fan speed for each.This seemed like a really great way to go, but without enough electronic engineering knowledge, it seemed like it would be a daunting task and a bit overkill for the basic problem that I wanted to solve: I just needed some fans to cool the cabinets. So I brought the problem back to its roots and began listing the requirements for my cooling project:

  • A minimum of 4 fans: 2 per cabinet, 1 per shelf.
  • Each fan needed to move as much air as possible in their sections
  • The setup needed to be low power
  • I needed to have a mesh filter for each fan to keep a) the cats from hurting themselves by sticking their paws into the fans, and b) to reduce dust.
  • I needed a way to control power to the fans, monitor temperature and optionally monitor or control fan speed.
Aluminum PC case fan mesh filter (left) and Cool
Master Turbine Master Mach 1.8 PC case fan (right)
In my research, I stumbled on the Cool Master Turbine Master Mach 1.8 PC case fans. These 120mm fans were large and moved more air than conventional PC case fans and seemed like the perfect fans to use. They were a little more expensive than other conventional PC case fans at $13 a fan, but for their size and power, it didn't seem so bad. I also found some aluminum PC case fan mesh filters for $3 a piece. These would be good to provide protection for the fan.
Finally came the question of providing power to the fans and controlling & monitoring them. I stumbled on the Thermal-Star 7 Fan Bus, an inexpensive power bus with fan speed and temperature monitoring. Though the unit could not control the fan speed based on the temperature, at only $20, I figured that this was not a huge loss as it could still power all 4 fans and monitor temperature and fan speeds. I figured I could still control the power to the whole setup using a simple outlet timer that I had lying around. Finally, since the fan bus required a molex power connector to power itself and the fans that were connected to it, I bought a $13 Coolmaster 12v Power Adapter.
Back panel with holes for the fans
Once the items finally arrived at my doorstep, I knew it was time to dig deep into my inner man and break out the power tools. I'm definitely not a handyman, so after some careful measuring and planning, I used a jigsaw to cut the fan holes and a drill to cut the screw holes to hold the fans into place into the back panels. There was a little bit of difficulty cutting and drilling the holes I needed as I wasn't aware that the panel was actually a laminate, so part of the wood stain began to splinter off the backing plate as I cut. This required the use of special laminate cutters and quick cutting to reduce the amount of scaring to the wood panel. But once the 4 fan holes and 16 screw holes were cut, it was time for the fun part: mounting the fans and wiring the whole rig up!
I love putting things together. It reminds me of my childhood with Legos and taking electronic things apart to see how they work, then figuring out how all the pieces fit back together. I even enjoy putting Ikea furniture together, though the amount of time it takes is a negative point for it. Thankfully this job was a lot easier than putting together an Ikea bed frame since all it took as putting small bolts with nuts through each of the holes to hold the fan and filter to the wood panels:
Mounted fan and filter facing outside the cabinet
The mounted fan on the inside of the cabinet
After all four fans were mounted, it came time to test all 4 fans to make sure there was no loose bolts and excessive rattling:
All the fans powered and spinning with the fan bus
Now came the time to disconnect the test and put the back panels back into the cabinet and connect it for permanent installation:
Fan panel installed into cabinet
Finally, I cleaned up and put everything back into the cabinets. I connected the fan controller to a power outlet timer so that the fans would not be running at the middle of the night - the least likely time we'd be actively using the equipment:
Fans running with equipment back in the cabinet
After having the setup running for the past week, I'm pretty impressed that everything came out pretty well. Though the setup is a little noisier than I had previously expected, it was no noisier than a regular PC. Before the fans, the cabinet with our DVR was the hottest and quickly reach 113F if the cabinet door was closed. Now, with the door closed and the fans running, the temperature in the cabinets usually stay around 88F. Though the major goals for this project have been completed, there are still some things that I have left to do:

  • Buy extension cables for the fans to the fan bus since the cables are just a tad bit to exact for the length of the cabinet.
  • Figure out how to reduce the noise of the fans further.
  • Build an Arduino controller to control the speed of the fans independently based on the temperature and time of day.

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