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Discussion Starter · #1 ·
In order to avoid condensation, is it as simple as making sure the coolant temperature doesn't drop below the ambient temperature? I'm curious because I'd like to create a shroud, or cold-box, to place around my mora, and see if I can drop temps to near-ambient during overclocking, using a standing A/C unit that I have. Though I'm not entirely sure it will prevent condensation all together, because only the mora would be placed in the cold-box, and not the rest of my bench setup. Which means fittings and cpu/gpu blocks would be exposed to higher ambient temperatures than what would be inside the cold-box, right?
 

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In order to avoid condensation, is it as simple as making sure the coolant temperature doesn't drop below the ambient temperature? I'm curious because I'd like to create a shroud, or cold-box, to place around my mora, and see if I can drop temps to near-ambient during overclocking, using a standing A/C unit that I have. Though I'm not entirely sure it will prevent condensation all together, because only the mora would be placed in the cold-box, and not the rest of my bench setup. Which means fittings and cpu/gpu blocks would be exposed to higher ambient temperatures than what would be inside the cold-box, right?
Stay above ambient or liquid electrical tape the board then use art eraser pack it in and some liquid electrical tape on the back of the board. I can help you insulate it if you wanna go sub ambient.
If you are doing a cold box ambient temps would be whats inside the box.
 

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Ok i just reread your post if you wanna run a ac unit straight into your rad it will probably drop below ambient tbh as room temps will be higher than whats coming out of the ac .. i thought you meant by cold box is running your ac into a actual sealed box to actually create a separate low ambient enclosure.. that would not condensate.
 

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Condensation occurs at the dew point. Dew point is based on relative humidity and dry bulb temp IIRC.

Or in other words, when moisture latent warm air hits a cold surface, the water will condense.

You can do the calc pretty easily but the challenge is controlling humidity. Unless you have a well controlled environment, it could be difficult. So the dew point could change.

For instance, in Southern Ontario (Canada), RH is commonly around 80-90% during the summer and could be 30-40% or less during winter.

The AC unit will have to pull in ambient air to cool and exhaust the heat. It’s unlikely the AC unit will manage to get the air feeding the “cold box” below ambient and of course, you will be able to control it.

The overall risk is low but you’ll have to manage the AC unit carefully initially just to make sure it’s not getting your loop temp to like <15C.
 

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Correct me if I'm wrong but technically, temps have to stay above the dew point, not ambient.
 

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Correct me if I'm wrong but technically, temps have to stay above the dew point, not ambient.
Correct but they are pretty close depending on a few variables like humidity.
Its alot easier to just say stay above ambient while you technically could drop a few degrees lower it starts getting tricky.
 

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Gonna followup on my last comment. Your gonna have to do the math on dew point every time you crank that setup on and getting that close to dew point id honestly insulate anyways. All its gonna take is one screw up on that math and your condensating all over your rig. While condensation isnt a big deal if you catch it right away hit it with some denatured alcohol and let it dry its a pita and lethal to your pc id you dont catch it.
 

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^ Not necessarily.

Could you (OP) explain the cold box in further detail?

Keep in mind an A/C technically doesn’t provide cooling. It’s actually removing heat.

What you’re feeling is simply the absence of heat. I mention this because… to get below ambient (conditioned or unconditioned air) is likey very difficult for any standard residential, portable AC unit.

As once you approach ambient, the AC unit will not only have to remove the heat inside the box, but also the heat surrounding the box.
 

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Just a quick follow up to explain in more detail.

I have this portable AC unit. 10,000 Btu/H

Yellow = intake (ambient)
Blue = exhaust (cold air)
Red = exhaust (hot air)

Liquid Product Fluid Kitchen appliance Home appliance


Your cold box, I assume is just duct work from the BLUE to your rad? If so, keep in mind your A/C unit thinks its trying to cool the intake air (your ambient, conditioned or unconditioned air).

I’m not sure how the A/C reads the temp but likely it has a sensor near the intake.

So your A/C really isn’t trying to cool your radiator (cold box), it’s really trying to cool the air feeding the unit.

Meaning, keep in mind what I initially said. It’s unlikely the cold air to be less than ambient but monitor it closely when you first set it up.
 

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Just a quick follow up to explain in more detail.

I have this portable AC unit. 10,000 Btu/H

Yellow = intake (ambient)
Blue = exhaust (cold air)
Red = exhaust (hot air)

View attachment 2524280

Your cold box, I assume is just duct work from the BLUE to your rad? If so, keep in mind your A/C unit thinks its trying to cool the intake air (your ambient, conditioned or unconditioned air).

I’m not sure how the A/C reads the temp but likely it has a sensor near the intake.

So your A/C really isn’t trying to cool your radiator (cold box), it’s really trying to cool the air feeding the unit.

Meaning, keep in mind what I initially said. It’s unlikely the cold air to be less than ambient but monitor it closely when you first set it up.
A/C's are heat pumps. They just move the heat. What your picture is missing is ducting for exhausting the heat out the room/window. Without ducting, the A/C is actually a heater as the net air temps will actually go up due to waste heat from compressor and fan.
 
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Yes, the photo I grabbed from the internet didn’t have the exhaust pipe. I tried to draw the heat in a direct line to illustrate it.

Still the same principle. A/C unit will have the be placed near a window to exhaust (move) the heat out of the environment/room.

My point is… will the A/C unit cause the loop to get below ambient? I don’t think so but I’ve never tried this. Also seems insanely inefficient :)
 

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Yes, the photo I grabbed from the internet didn’t have the exhaust pipe. I tried to draw the heat in a direct line to illustrate it.

Still the same principle. A/C unit will have the be placed near a window to exhaust (move) the heat out of the environment/room.

My point is… will the A/C unit cause the loop to get below ambient? I don’t think so but I’ve never tried this. Also seems insanely inefficient :)
It really is. If you have a spare window unit for this just pull the fan off of it and put the condensor in a ice chest filled with glycol.. phasechange water chilling is pretty efficient and the route im probably going for benching.. thats if i dont go full singlestage phase.
 

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Meaning, keep in mind what I initially said. It’s unlikely the cold air to be less than ambient but monitor it closely when you first set it up.
If the A/C unit cools the intake air down at all, won't it be below ambient? It won't cool the room below ambient in that configuration, but it will cool the exhaust below ambient.

I have seen the exhaust from an A/C unit cool down metal objects in front of it low enough to condense water when exposed to ambient air. It is pretty common for the outside of the box to condense if you trap the exhaust somewhere. The exhaust can get pretty cold in my experience.
 

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If the A/C unit cools the intake air down at all, won't it be below ambient? It won't cool the room below ambient in that configuration, but it will cool the exhaust below ambient.

I have seen the exhaust from an A/C unit cool down metal objects in front of it low enough to condense water when exposed to ambient air. It is pretty common for the outside of the box to condense if you trap the exhaust somewhere. The exhaust can get pretty cold in my experience.
This was exactly what i meant. And the temp of the ambient air around his rad isnt what hes worried about. The temp around the tubing in his pc is. Thats where condensation is gonna matter. If the water temp drops below dew point its gonna condensate.
@op you are gonna have to monitor water temps
 

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If the A/C unit cools the intake air down at all, won't it be below ambient? It won't cool the room below ambient in that configuration, but it will cool the exhaust below ambient.

I have seen the exhaust from an A/C unit cool down metal objects in front of it low enough to condense water when exposed to ambient air. It is pretty common for the outside of the box to condense if you trap the exhaust somewhere. The exhaust can get pretty cold in my experience.
You’re probably correct as I simply don’t know what is the temp of the cold air being exhausted from the unit. If its like 20c lower than the intake air, of course you will quickly run into issues. As the A/C is technically trying to lower the ambient of the room (intake).

Has anyone measured what temperature that air (typically) is?
 

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You’re probably correct as I simply don’t know what is the cold temperature being exhausted from the unit. If its like 20c lower than the intake air, of course you will quickly run into issues. As the A/C is technically trying to lower the ambient of the room (intake).

Has anyone measured what temperature that air (typically) is?
Ok so i have a window unit taken apart to build a chiller. My ambient in my room is normally 70-72 with my main unit cooling the room. I put the thermostat in the vent to see how cold the air was getting and the thermostat on the unit dropped 15 degrees very quickly. I had the unit set on 65 and it went below that i couldn't exactly measure how far as i dont have a laser thermometer but the acs thermostat showed roughly 60 degrees when the compressor kicked off and it was still trying to drop.

Ik with a water chiller made with a 7k btu unit you can get water temps around -30c so id believe the air coming out is well below ambient
 

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Discussion Starter · #17 ·
Thank you for all the responses!

My idea was to use the A/C unit to drop the temps as close to ambient without getting to ambient or lower. As far as efficiency, it wouldn't exactly be a priority since this wouldn't be a daily driver kind of thing. It would just be used during the 3-5 minutes of benchmarking, depending on what I'm using to benchmark at the time. And at this point, with all the good points and information posted here, I feel like I could probably just run the A/C unit so that it is blasting cold air into the intake fans on the rad, and that may allow me some amount of drop in coolant temp, but most likely wouldn't approach ambient so I wouldn't need to worry too much about condensation. So I guess the question at that point would be, would the drop in coolant temp allow me to push the processor another few hundred megs. I would need to first see how far I can push the processor without the aid of the A/C unit.
 

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Thank you for all the responses!

My idea was to use the A/C unit to drop the temps as close to ambient without getting to ambient or lower. As far as efficiency, it wouldn't exactly be a priority since this wouldn't be a daily driver kind of thing. It would just be used during the 3-5 minutes of benchmarking, depending on what I'm using to benchmark at the time. And at this point, with all the good points and information posted here, I feel like I could probably just run the A/C unit so that it is blasting cold air into the intake fans on the rad, and that may allow me some amount of drop in coolant temp, but most likely wouldn't approach ambient so I wouldn't need to worry too much about condensation. So I guess the question at that point would be, would the drop in coolant temp allow me to push the processor another few hundred megs. I would need to first see how far I can push the processor without the aid of the A/C unit.
Possibly. Your gonna need a 30c temp drop on your processor roughly as voltage is gonna scale horribly depending on how close you are to the limit. Remember colder the chip better it clocks.
Honestly ambient overclocking you wont really notice too much of a difference. When you get down to -20/30c is when it starts to get interesting
 

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Just put the whole pc in a box that is connected to your AC that blows through the box into the room, the air coming out of the AC has no chance of condensing water as the coldest point was the evaporator just before it go's out. so long as that outlet for the AC is taped up good your pc is safe!

edit: to be on the safe side run the pc for awhile after the ac is turned off to warm it back up to room temps. (also when your turn off the AC you want to turn off the fan on the AC as well at least for a few min until the pc has warmed up a fair bit.)
 

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Just put the whole pc in a box that is connected to your AC that blows through the box into the room, the air coming out of the AC has no chance of condensing water as the coldest point was the evaporator just before it go's out. so long as that outlet for the AC is taped up good your pc is safe!
This a chiller box is the way to go.
 
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