I've been running two mining rigs in my basement for a few months now, with a total of eight high-end graphics cards (4x GTX 1080Ti, 3x GTX 1080, 1x GTX 1070). Back in July and August, it didn't bother me so much that my basement ambient temperature was regularly in the 85F (29C) range. It was uncomfortable, but I kept telling myself that winter was coming soon and once it did, I would be "heating my house with blockchain," and the temperature down there would get more comfortable. I've got a whole-house DC fan that runs 24-7 circulating air throughout my house, so I thought for sure everything would work out.
A couple weeks ago when outside temperatures reached 32F (0C) during the day and even colder overnight, I was extremely disappointed to find out my basement was still 85F ambient and while some of that heat certainly was making its way to the upstairs floors, it was clear that the circulation wasn't happening the way I had hoped. My gas furnace still kicked on from time-to-time, which bothered me because I had a literal sauna in my basement.
I tried various "easy" methods to fix this with box fans trying to force the air to circulate more efficiently but ultimately nothing cooled my basement off other than opening the windows and allowing the freezing air into my basement. Of course as soon as I'd do that, my gas furnace would kick on so that was no solution.
I obsessed over this issue until I found a solution, and I finally cracked the code.
Why is my HVAC circulating fan not working for this?
Even though my HVAC system has intakes in the basement, they are at floor level. This makes sense --by design-- because usually the air you're trying to circulate out of your basement is cold air. Since hot air rises and cold air falls, obviously the most efficient place to capture the cold air in your basement is on the floor.
But could this really be my problem? If the basement is 85F all day, wouldn't air near the floor be hot too? To test this, I decided to take a temperature reading at the floor.
79F was the reading. So while at desk height, the temperature measures 85F, the air near the floor that is getting sucked into the air vent and circulated around the house is actually 6 degrees cooler.
So what about the air at the ceiling level? I took my temperature probe out and sat it on top of a shelf near my ceiling. Five minutes later and....
90F was the reading at the ceiling. Wow! An 11-degree temperature difference between the ceiling and the floor. No wonder all this hot air was stuck in the basement.
Solution: Install a vent in the ceiling
After getting the 90F reading at ceiling level, I immediately knew what needed to be done: I need to install some sort of exhaust system that will intake from the ceiling and exhaust into my living room upstairs. I have drop-ceiling in my basement, so I didn't figure this would be a very complicated project.
After doing some research online, I found the AC Infinity Cloudline T6. It is a turbine-style fan that has many uses, but is most commonly sought-out as an exhaust fan for hydroponic grow operations.
I was drawn to this as a solution for a few reasons:
- It comes with a thermostat, so you can set it so that it lowers the fan speed or turns off entirely at a certain temperature.
- The reviews on the product indicated that the turbine-style fan was quieter than normal HVAC duct fans
- Honestly, it's a slick-looking fan
While waiting for the fan to ship, I tried an alternative
I had some free time over the weekend and my Cloudline T6 fan wasn't going to arrive for a few days. I needed to go ahead and install the extra floor vent in my living room and get the ductwork set up and ready for when it arrives. While I was at the hardware store, I thought I would try out one of the cheaper "HVAC duct booster fans" to at least test out my plan.
The duct booster fan was rated at half the airflow of the Cloudline T6, but I thought that really any amount of 90F air I can push upstairs would make a big difference.
I got the floor vent installed and I hooked up the cheap duct booster fan and fired it up. The air flowing through the vent upstairs was minimal (which was surprising to me --- you could barely feel any air flowing through) but I could feel that the air was very hot so I let the fan run for a couple days to see what happened.
The good news is that it helped, bringing the peak basement temperature down from 85F to about 81F. I wasn't going to balk at a 4-degree reduction and it was clearly making a difference upstairs with my gas furnace running less often. I was really crossing my fingers that the Cloudline T6 would be a significant improvement, though.
Cloudline T6 Arrives... Blows Me Away (Literally)
I got the Cloudline T6 mounted and hooked up to the ductwork. After reading the directions I found out the easiest way to get started is to put the thermostat in manual mode and just set the fan speed where you want it. I turned it on and quickly ratcheted up the fan to its maximum setting.
Whoah....
The fan itself was quiet, but the sheer amount of air flowing through the 6" ductwork was making a good bit of noise. I went upstairs to the floor vent in the living room and where before I could barely feel any air flowing out of the vent, now my window drapes were flapping like they were in the middle of a hurricane!
While the Cloudline T6 is rated at twice the airflow of the cheap HVAC booster fan I was using, it turns out the static air pressure was strong enough that the cheap HVAC booster fan wasn't even able to push that much air through. In laymen's terms, there was enough air resistance that the blades were spinning, but really not that much air was moving. So instead of seeing twice the airflow with the Cloudline T6, the efficient turbine-style blade was actually pushing out at LEAST 10x the airflow I was seeing with the other fan.
But does it work....
The moment of truth had arrived. I let the Cloudline T6 run on full blast overnight so it was time for me to go downstairs to see what the temperature was. Right away when I went down the stairs, the room FELT much more comfortable. As we established earlier, there are different temperatures at different height levels and even in different parts of the room. I got downstairs and it almost felt like I didn't have $10,000 worth of computer equipment buzzing away. I got to my desk and looked at my thermometer...
77F was the reading. Wow! The temperature in my basement office is finally tolerable for me to sit here and write this article! A week ago, there was no way I was sitting in this 85F hell-hole for longer than about 15 minutes. For about $150 worth of parts and a little bit of manual labor, I've been able to push this nasty hot air up to my main floor where it can be efficiently circulated by my HVAC system and I can actually comfortably hang out down here!
Final Thoughts: AC Infinity Cloudline T6
I had said earlier that the sound of the air being sucked through this fan is pretty loud when it's at 100% power, and that is true. It's not intolerable in my living room, but it certainly is not a sound you want 24-7. The good news is if you turn the power down even one bar on the fan setting (there are 6 bars), the noise is reduced by at least 50%. If you turn it down to 3 bars, it is almost silent and still moves probably 5x the air that the previous cheap fan was moving.
Otherwise, I can't say enough good things about this setup. Is it a little over-the-top? Sure, but I also don't want to put my entire basement floor out of commission so I can mine cryptocurrency. I also just hated to waste all that perfectly good heat! My furnace literally has not run since I installed this setup. I am finally heating my house with blockchain.
Do any of you have any weird/quirky things you've done to manage the heat your rigs produce?