Cassandra.org
Story
Server and storage closet.
Ten years earlier, I had converted what was previously a sewing closet off our kitchen into something more useful. Half of the upper portion would host all the networking and computer equipment while the other upper half would store our games and media. In the the lower portion I put in a cabinet drawers I had built for that purpose. See the Server Closet Project Page or Closet Cabinet Project Page for more details on those projects.
The electronic equipment consisted of a couple of servers, the cable modem, WiFi router, a bunch of network switches, battery backups (UPS) and the media receiver. This would all generate a fair amount of heat, so I had to design it accordingly.
My original solution sort of worked, but had some problems. Five years later I tried to improve the ventilation. This helped a bit, but not as much as I hoped and I still had issues. The third time is a charm, and this is about how I finally solved the issue.
Previous Solutions
Original fan outflow.
Original fan inflow.
When I original built the closet, I had an intake and outtake fans on a controller that monitored the temperature inside the closet. This worked, but the fan would come on too frequently. The fans were also a bit loud, despite my purchasing the quietest fans I could find. They were not all that loud, but loud enough that you could hear them, and I think it was just my being conscious of them cycling that was the most bothersome. I did not want to have to continually, actively cool the closet.
There was also the risk of burning out equipment should my fan controller fail without my noticing it or while we were away.
Original closet lower vent.
I found that if I just left open the closet door a crack (just an inch or two), that was enough to keep the closet cool enough and the fans would almost never cycle. I did not like keeping the door open, and many times it would be inadvertently closed and I would only notice when I was around and would hear the fans running again.
Since it seems to take a very little more air flow to keep it cool, I decided to install a vent in the lower half of the door. This custom-made vent turned out nice, but it did not improve the situation and cracking the door was still required. See the Server Closet Vent Project for how I built that vent.
The Solution
My theory on why the door vent did not work was due to the convention: hot air rises. The lower vent would be good at pulling in cool air, but there was only a very small outlet vent at the top for the hot air to escape. So the lower vent was only really pulling in as much cool air as could escape from the top vent and that was not enough. What I needed was an upper outlet vent with surface area equal to the lower vent. Then I could get a natural convention cycle flowing and likely not even need any fans.
My theory seems to be right. After finishing this project, we can now keep the door closed and the temperature-controlled fans (which I retained for safety) have never come on.
Preparation
I did not want to remove all the computer equipment from the cabinet because that is a complex project. The wiring in pretty intense and I still needed all the equipment to be running. I used a painting tarp and some support poles to cover everything. There would be sawdust, drywall dust, spackle and paint all involved in this project. I then removed the upper fan, its grill and moved the fan controller out of the way.
Masking off computers with tarp.
A small part of the network wiring.
Support pole for tarp (closeup).
Original fan vent hole (from inside closet).
Original fan vent hole (from outside).
Temperature and fan controller.
Exploratory Holes and Demolition
At this point, I only knew that I needed as much surface area as the door vent, but what size vents and how to space them would depend on what I found after tearing the upper wallboard off. In the end I would also need something firm to screw the vent grills into (maybe a wall stud).
Original vent hole support structure.
Original fan vent hole and initial cuts.
I started by demolishing the area around the original fan outlet since that had some extra plywood pieces I added for support that would have to go away. I then used a series of conservatively chosen exploratory holes to I could poke inside the wall to locate where the existing wall studs were.
Original and exploratorey hole.
Expanded original hole.
After all exploratory holes.
Front wallboard removed.
No matter what vent grill configuration I used, I did want it to be symmetrical and centered over the closet. I found the existing studs were neither evenly spaced, nor was the middle one centered on the door. I would need remove these studs and install new ones.
What was serendipitous was the space between the door header wood and the wall header wood. It was almost exactly 6 inches. This was serendipitous because it meant I could use standard, off-the shelf vent grilles as 6 inches is a very common vent height. It was possible I would need to make custom grills if the geometry did not cooperate. That would have expand the scope of this project considerably.
Repositioning Studs
What was even more serendipitous was the width I had to work with. A 6x12 inch vent grill is super common, and 4 of these not only gave me slightly more surface area than I needed, but they would fit comfortably along the upper wall area. Thus, now I knew what size vent grills I would use and I set about moving the wall studs so they would fit evenly between them.
Shimmed new studs.
New stud support before removing old studs.
The existing studs were probably not load bearing, but I did not want to take any chances. I cut the new studs and inserted them with shims before I cut out the old ones.
To remove the existing ones I used a jigsaw cut in the middle, then hammered them to pull them away from the nails.
Finishing
New studs with blocks for screws.
Wallboard and block pieces for new studs.
The way the vent grills were spaced, one stud was not wide enough to screw two adjacent grill into. I had to create some additional blocks to extend the area I had for screwing in the vent grills.
I also needed to fill in the wallboard over the studs to make them even with the rest of the wall.
Initial spackling pass.
New studs with wallboard and blocks.
With all the studs moved, extra support block and drywall patches, it was time to spackle and paint.
I used the spackle that is pink until it dries.
None of the paint we had lying around matched well enough, so I went to Home Depot and had the best experience ever in buying paints there. Super helpful, knowledgeable and stickler for details. The match was perfect.
Installing Fans
New fans installed (closeup).
After fans installed (from right).
Although I hoped I would have enough of a convention flow to not need active cooling, since I already had the controller, the fans and it was all wired up, I decided I would install them as a safety measure.
Having them installed also allow me to know if this project was a success: if they never come on, then problem solved.
Installing Vent Grills
Aligning vent grills.
Vent grills ready for installation.
Given the very common 6x12 inch size, I had a wealth of choices when I bought the vent grills. I found some that were more visually attractive than most and were of a decent quality.
The vents were white, which would have look OK, but by painting them the same color as the wall, they would not draw the eye as much and look more pleasing.
Final Result
Final view (from right).
Final view (from left).
I was very happy with the final result and not just because it solved the heat problem, but because I think it wound up looking visually pleasing too.