AIO cooling. Why is it done backwards?

Don B. Cilly

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Rather than flipping the unit (easier said than done, what with cables and all), what I think I'll try is make some holes at the top (sides) to at least let some hot air out when the fans aren't running.

[EDIT] This is pretty much what my main unit looks like. Sides and top are completely closed, hot air just accumulates there.

Screenshot_0621_123447.png
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Bobert

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Yeah, this is very common. Pretty much all of them are like this. They are designed to work that way, and it confused me for a long time.

I talked to a bitcoin miner who designed large scale systems, and he says that convective flow would contribute very little benefit here. The air will go where you tell it to. The amount of air that the fans push through the unit is plenty for dissipating the heat. Whether you add convective flow into the equation or not will not change performance by any noticeable amount.

You can run your own experiment. Hang the unit upside down and put a heat camera on it. If there is a huge difference, let us know.
Somehow last night when I started to respond to this post and realized I was to tired to give a coherent response I somehow posted a blank response. I guess I really was to tired. I wonder if part of the reason why victron is used successfully in tight spaces is partly because they don’t throw away any advantage no matter how small. It seems to me that in a relatively confined space were a small
Vent hole is below the unit and a small vent is above the unit that the space would force the recycling of very hot air. An absorption fridg disapates dramatically more heat than a AIO unit using convention alone and most of these fridges are installed improperly. A severely bad installation will require multiple fans to make up the difference and sometimes that doesn’t even work. Let’s say ay you have a AIO mounted in a shallow 32”’closet whither a 1” gap at the top and bottom of the door. It seems to me that the natural convection that would normally be more than adequate to keep the space nearly the same temperature as the adjoining room except that the reverse fans from the AIO would disrupt natural convection.

Since my unit cools fine I’m not going to sweat it but it seems to me that “It would contribute very little” would not cause a designer to not incorporate an advantage no matter how small unless there’s some other advantages from the reverse flow ie some sort of cost savings or more advantageous placement of internal components or something like that. My question was is the reverse flow an engineered design or just a random decision at assembly because the engineer says “it doesn’t matter that much”. Nobody seems to know.
 

sunshine

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Why don’t the fans blow up into the unit instead of sucking down?
Probably the real reason is that were originally based on standard inverter designs where the inverter lays on a flat surface rather than vertically with the air coming in from the front and out the back where all the wires are and out the window.
Maybe it would not be a good idea to reverse the fan as the original designers may have prioritised which parts get the flow first.
 
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Will Prowse

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Somehow last night when I started to respond to this post and realized I was to tired to give a coherent response I somehow posted a blank response. I guess I really was to tired. I wonder if part of the reason why victron is used successfully in tight spaces is partly because they don’t throw away any advantage no matter how small. It seems to me that in a relatively confined space were a small
Vent hole is below the unit and a small vent is above the unit that the space would force the recycling of very hot air. An absorption fridg disapates dramatically more heat than a AIO unit using convention alone and most of these fridges are installed improperly. A severely bad installation will require multiple fans to make up the difference and sometimes that doesn’t even work. Let’s say ay you have a AIO mounted in a shallow 32”’closet whither a 1” gap at the top and bottom of the door. It seems to me that the natural convection that would normally be more than adequate to keep the space nearly the same temperature as the adjoining room except that the reverse fans from the AIO would disrupt natural convection.

Since my unit cools fine I’m not going to sweat it but it seems to me that “It would contribute very little” would not cause a designer to not incorporate an advantage no matter how small unless there’s some other advantages from the reverse flow ie some sort of cost savings or more advantageous placement of internal components or something like that. My question was is the reverse flow an engineered design or just a random decision at assembly because the engineer says “it doesn’t matter that much”. Nobody seems to know.
Ok, set up an experiment and show us your results. Or ask the engineers at voltronic and let us know their response.
 

BiduleOhm

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I think you're both right @Bobert and @Will Prowse :

Bobert is talking about natural convection with fans not running. In that case, yes, hot air will rise and escape at the top/sides and pull cold air from the bottom.

But, as soon as you have the fans running then any natural convection is totally overpowered by them, that's what Will was trying to say.
 

Bobert

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Bobert is talking about natural convection with fans not running. In that case, yes, hot air will rise and escape at the top/sides and pull cold air from the bottom.
Absolutely I get no fan operation until I reach around 300w solar in and at the same time 300 ish watts of inverter output. Solar input seems to require much less fan than the inverter
 

Skinny76

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My Growatt seems to pull in from the bottom and blows out the top left side. No vent holes on top, which I like so maybe dust doesn't fall though when the fans are off. I will say, when I'm maxing out the mppt or the ac to dc charger, it blows pretty warm.
 
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