Brainstorming Further Cooling Improvements To The Linux Benchmarking Room

[Mark Rose]

Mark Rose makes some good points (especially the reminder that direct air exchange with outdoors is going to be a lot cheaper than any kind of air conditioning or heat pump in the summer), although I doubt Michael is going to be excited by the idea of moving the servers twice a year

The classic application of ground cooling (apart from root cellars, of course) seems to be the combination of a solar chimney with an air intake that flows underground, and the modern form of that seems to be an exhaust chimney plus an evaporative cooler at the top of an intake tower. The cooler air from the swamp cooler flows down into the conditioned area, and hot air flows up the exhaust chimney.

Of course you can ditch all the chimney stuff and just use fans these days, but you do want a fair amount of airflow and fans make for power bills too. Moving air from the server room into the rest of the house is good in the winter when you can get free heat, but IMO in the summer you want to exhaust directly outside and pull some air in from outside (on the shady side of the house) as well rather than running all the replacement air through the rest of the house which in turn cycles the A/C to keep the house temp down.

The problem with underground intake tubes is that critters like to make homes in them. Unless you live in a permafrost area, they are above freezing all year round.

It's kind of unfortunate that the heat is spread out throughout the basement, and not concentrated into a single spot that would be easy to exhaust. One option would be building some cardboard ducting for each rack, and installing air vents by each to exhaust air directly outside, but it seems the basement is completely subterranean (no windows). Even with doing the airflow idea I suggested, having the heat fill the room will still heat the floor above, increasing the A/C load.

People keep suggesting solar, but I believe they're going about it the wrong way. Instead of spending a fortune on solar electricity, a better idea would be to build a solar chimney, like you suggest, and solve the problem of too much hot air directly. I would build a tall black stovepipe tube in the sunniest spot and anchor it to the house with some standoffs. The black will absorb the sunshine and make the metal very hot. The air inside will warm up, and create a strong convective current. The bottom of the tube can then suck air out of the basement, near the ceiling. On cooler days when the heat is desired, shut the tube off, as the tube will siphon even -40 temperatures. Such a tube will get very hot in the summer, so care must be taken and space must be left between the tube and the house. I would go with 6"+ black stovepipe (lesser diameter pipe would restrict airflow). A few cinder blocks will serve as a foundation for the bottom of the pipe. This can easily be done for under a grand. The taller the pipe, the stronger the siphon. Also, a fresh air supply will be needed in the room. I wouldn't rely on pulling air from the rest of the house as new construction is pretty air tight, and the chimney would fight with the dryer, bathroom fan, etc. This idea might not be possible if an HOA is involved though.

[Mark Rose]

I'm coming to pretty much the same conclusions. If the underlayment has high thermal resistivity (is a good isolator), that could be a gain. Porcelain vs vinyl won't make a very big difference. (Porcelains thermal conductivity is about 6 times that of vinyl, so R-factors should be around 0.01) Most of the thermal resistivity of your floor would come from the concrete (or perhaps the underlayment or theoretical insulators below the concrete).

Given how deep his basement is, chances are he's well above the water table, and there will be no moving water to pull heat away from the basement. So I think the ground will warm up to near equilibrium, which will slow down any heat transfer, regardless of the ambient starting temperature. Given that the heat load for the last six months, this has probably largely happened. It would be different if in the cooler months the heat were used to warm up the basement. As you know, It's kind of like charging a battery: you have to discharge it if you want to store more energy. Yes, there's a little internal leakage, but it's slow. I think different tiles won't make a difference. I bet Porcelain would only feel cooler as it will transfer its latent coolth to the feet faster (once the underfloor is the same temperature, the tile different won't matter). Instead of tiles, I would spend the same money on more ventilation.

[Mark Rose]

ROI is the highest with Solar, no doubt, but on a budget, stupid question, what about a natural gas powered generator to moderate the cost until you can afford solar.

It's still cheaper to buy electricity from the grid than to run a small generator. Plus you have the noise and maintenance issues, like changing the oil weekly if you run it 24/7.

[kurly_b]

Not where I live. We are required by law to connect to the local utility. $400 a month for 600 square feet condo!

But your point is well taken.

I agree that the solution is to exchange the air and remove the heat.
Do the math and figure out the exchange rate need to turn over enough air to keep the servers running.
I personally don't have my dual xeon's even in a case. And they are not in an air conditioned environment, running 24/7. I just keep moving the air, with 8 120mm fans.

[bridgman]

with 8 120mm fans.

With 8 120mm fans you could build one of these:

[kurly_b]

LOL.
That looks like home to me.... I am Florida Boy, after all.
I had a choose between air conditioning the living room or my dual xeon's..... Both were equal in price, and power usage, server one.

Oh... BTW, my wife just informed me that the power bill for the condo is almost $800 a month now.
I had know idea.....

[Michael]

The problem with underground intake tubes is that critters like to make homes in them. Unless you live in a permafrost area, they are above freezing all year round.

It's kind of unfortunate that the heat is spread out throughout the basement, and not concentrated into a single spot that would be easy to exhaust. One option would be building some cardboard ducting for each rack, and installing air vents by each to exhaust air directly outside, but it seems the basement is completely subterranean (no windows). Even with doing the airflow idea I suggested, having the heat fill the room will still heat the floor above, increasing the A/C load.

It's below ground but two glass block windows that are within window wells for some ventilation. I installed glass block windows for greater security but unfortunately only very small air windows.

The heat doesn't have much of an impact on the floor above since before drywalling the ceiling I had installed Roxul stone wool insulation with R15 value. Additionally, above that area is kitchen and for that I have the subflooor plus 1/2-inch cement board and then porcelain tile atop that. So it's pretty well sound proofed and didn't notice the room above it getting hot short of having the exhaust fan blowing out of the basement.

People keep suggesting solar, but I believe they're going about it the wrong way. Instead of spending a fortune on solar electricity, a better idea would be to build a solar chimney, like you suggest, and solve the problem of too much hot air directly. I would build a tall black stovepipe tube in the sunniest spot and anchor it to the house with some standoffs. The black will absorb the sunshine and make the metal very hot. The air inside will warm up, and create a strong convective current. The bottom of the tube can then suck air out of the basement, near the ceiling. On cooler days when the heat is desired, shut the tube off, as the tube will siphon even -40 temperatures. Such a tube will get very hot in the summer, so care must be taken and space must be left between the tube and the house. I would go with 6"+ black stovepipe (lesser diameter pipe would restrict airflow). A few cinder blocks will serve as a foundation for the bottom of the pipe. This can easily be done for under a grand. The taller the pipe, the stronger the siphon. Also, a fresh air supply will be needed in the room. I wouldn't rely on pulling air from the rest of the house as new construction is pretty air tight, and the chimney would fight with the dryer, bathroom fan, etc. This idea might not be possible if an HOA is involved though.

Fun idea, but wife wouldn't approve of an 8-inch stove pipe running the height of the house.

[Michael]

I got an estimate for (26) 200 watt transparent panels to go over an outdoor living space, including mounting assembly's for $15k, needed to add inverters and such.
CAT 5 Hurricane specs were meet also.
Something like these guys - http://www.solar-constructions.com/w...-solar-panels/

Does that $20K include installation, batteries, inverters?

Hell you can buy a pallet of panels (24) 250 watt on Amazon for $6k.
Need to fabricate the mountings yourself, but you seam pretty handy. Stainless Steel Unistrut is a wonderful thing......

Enough with the pie in the sky, solar.
If you rip up the floor to put in tile, run a floor radiate piping under it. Instead of hot water, circulate cold water through it.
Then run wye off your existing duct mounted fan, put damper in it, to redirect it from exhausting upstairs and route it outside, get another duct fan for make up air, duct to the bottom..

It was just a quick quote, but I believe it included anything. Maybe within a few years of saving extra will be able to afford solar.

[bridgman]

It's below ground but two glass block windows that are within window wells for some ventilation. I installed glass block windows for greater security but unfortunately only very small air windows.

How small are we talking ? You just need to be able to get ducts in and out...

[feydun]

.....