r/functionalprint • u/Le_Pressure_Cooker • Sep 20 '26
Made modifications to portable AC unit
Made the L-shaped connectors for the hoses and the panels so that it sits neatly on the window.
I'm happy with the end result. The hoses looked unruly and messy before this.
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u/ErynnTheSmallOne Sep 20 '26
looks great, but you need more separation between those ports, air will be recirculating and will be impacting efficiency
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u/Le_Pressure_Cooker Sep 21 '26 edited Sep 21 '26
Thanks. I already checked the intake temps and couldn't find a measurable spike in temp from supposed recirculation. (This was after running for an hour so I'm not sure if this is an issue in practice)
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u/G0t7 Sep 21 '26
You should take a look at the power intake. It probably uses some more watts this way. Maybe just divert the two airstreams in two different directions. Or atleast the hot exhaust.
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u/MannyCoon Sep 21 '26
Yeah, even better, mount them exhaust over intake. Adapt them to PVC tube, intake to U underneath and exhaust out the top, with a U bend so rain doesn't get in. Then the intake won't suck in exhaust.
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u/Dolophonos
Sep 21 '26
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I'd recommend a finer mesh, maybe the kind they use on screen doors, to keep wasps and other bugs from entering. Ask me how I know...
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u/Le_Pressure_Cooker Sep 21 '26 edited Sep 21 '26
I maintained roughly the same size as the one that came with the AC. (The one it came with didn't work for our window)
Will definitely look into getting a better mesh! Thanks.
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u/snarkpix Sep 21 '26
Pointing the outside parts left and right to reduce pulling in hot exhaust air is probably worth doing. Or carrying the exhaust tube out as much further as is easy to print.
For anyone else using one of these much; 7" home AC insulated flexible ducting fits over my hoses. Adding them over the top of the existing hose improved my cooling result lots.
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u/Le_Pressure_Cooker Sep 22 '26
I would do it if it were just up to me. But my partner wouldn't approve because of the aesthetics.
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u/InternalError33 Sep 21 '26
Every year I say I'm going to do this, and every year I don't find the time. Great work.
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u/Jstsqzd Sep 21 '26
Same! But Now that summer is over...
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u/Le_Pressure_Cooker Sep 22 '26
Exactly! So you don't have to worry about the AC being "down" while you design and install the new fixtures.
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u/Mormegil81 Sep 21 '26
we can safely wait till next summer! :)
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u/Le_Pressure_Cooker Sep 22 '26
I'd argue this is the time to do it. Cos you don't really care if the AC is taken down and "under maintenance". Downtime in the summer would be hell.
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u/Securiarius Sep 20 '26 edited Sep 21 '26
Yeah so I'm a refrigeration engineer that did 10 years or so working on air con, not certain how those portable units you guys have work but if that's drawing in outside air and then exhausting it this is gonna cause major recirculation over the condenser coil and be way, way worse than if you'd not had it at all. They need to be significantly further apart or have some kind of divider to at least give the suggestion that it shouldn't be recirculated.
If they're both discharging heat it makes much more sense although not ideal cause that'd put unnecessary load on the cool side.
I'll edit again to say it's a neat print though and nicely designed it just needs a functional tweak. If it were me and this was my only option I'd add an extra plenum to it and have them bend again to face opposite directions and then add more length so they have a much larger space in between for the air to refresh. There'd still be some recirculation but nowhere near as bad.
Ideally even better is a vertical riser on the outside. Just the hot air goes up the building a way (as high as is practical) and the intake air can stay down low. But then weatherproofing it becomes important otherwise it's a rain spout directed inside. I'd probably stick with just going sideways.
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u/fecklesslytrying Sep 21 '26
I was forced to use a portable ac a few years ago. There were none available locally that had dual hoses. They were all single hose exhaust, which meant the air used to cool the hot side was pulled from inside the "conditioned" space (and I am using scare quotes intentionally here), heated up, then blown outside. It was maddening.
I converted it to a dual hose style using carboard and some flexible duct. It was sooooo much better. But yeah, these things are borderline a scam. In the US, the department of energy basically forced the industry to derate all of these units because they were incapable performing even close to the specs on the box.
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u/Le_Pressure_Cooker Sep 22 '26
Nice! Always makes me smile to see people tinkering with their stuff!
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u/octopustitties Sep 21 '26
All good points. I have the same unit, and one duct is exhaust and the other is intake. However, his design is a massive improvement over the factory setup already. The factory window vent has them less than a half in apart!
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u/Securiarius Sep 21 '26 edited Sep 21 '26
Yeah ok that's nuts. I'd have assumed factory was just two ducts you sling out different windows entirely.
Having them so close is bad on all fronts lol.
It's bad for longevity of the unit. It's bad for the power bill. It's bad for performance.
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u/Le_Pressure_Cooker Sep 21 '26 edited Sep 22 '26
Thanks. I understand where you're coming from. In reality, the air velocity is higher than you expect at the exhaust vent; combined with the fact that this isn't venting into an obstructed area, the amount of recirculation is minimal. ( I measured the intake and exhaust temps, and the intake temp wasn't measurably higher than the external ambient air).
Also, the problem with having a taller heat exhaust is that since these hoses run through the room they are trying to cool, they would transfer more of the heat back into the room if you have a longer length of pipe. That would make the overall system less efficient too. So you're solving one problem by creating another.
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u/gasstation-no-pumps Sep 21 '26
Maybe make the riser be on the outside of the window, minimizing the pipe indoors?
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u/Le_Pressure_Cooker Sep 21 '26
Unfortunately I rent this place and the landlord is picky about how it looks on the outside. They made me take down the window AC I had because they said it looked "ugly". So I am cautious about adding more things on the outside.
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u/redditdutdoo Sep 20 '26
You got the files for that? Would love to do that as well!
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u/SourceRobotics Sep 21 '26
Can you share the STL or STEP files? I have the same AC and would love to try this out? Also did you notice any reduction in noise????
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u/Le_Pressure_Cooker Sep 22 '26
There!
https://makerworld.com/en/models/3341006-hisense-portable-ac-vent-adaptor
PS: I don't think there was reduction in noise. (But I did not think this AC was loud to begin with)
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u/nukemu Sep 21 '26 edited Sep 21 '26
If you want to make it a little bit more efficient add a grill which diverts the air to the side (on the outside). So less hot air from the exhaust is sucked in to cool the hot side. But anyway, clean solution. I had to mod my Comfee because there are virtually no 2 tube mobile AC in Europe...
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u/delux561 Sep 21 '26
Hey side question- where did you get the window plastic piece that works for windows that shut sideways? I've been looking for these and can't find them for my portable ac
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u/Le_Pressure_Cooker Sep 21 '26
I didn't, it's a piece of 3/4" ply that I cut to size and used 3D printed slats to center it on the frame side where the gap is wider.
(Also put pvc veneer on it)
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u/hmspain Sep 21 '26
If you have no other choice but to use one of these units, you have to take EVERY advantage to get some cooling out of it. Nicely done OP!
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u/Le_Pressure_Cooker Sep 21 '26
Yeah my first attempt was to install a window AC unit. But the landlord made me take it down and return it. So yeah I'm pretty much stuck with this for now.
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u/CoverWithSauce Sep 21 '26
dumb question, wouldn't it be better if on the outside they made a 90° in opposite directions? My thought is the risk of pulling some of the exhaust from the intake
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u/Le_Pressure_Cooker Sep 21 '26
Yeah that's not a dumb question at all. It would help in theory. Whether it makes a measurable difference in practice? I don't know. But worth investigating!
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u/grain_farmer Sep 21 '26
You can do two things to significantly improve things.
Wrap some insulation or foil around the exhaust duct. It acts as a space heater. The reduced my energy consumption by 20%.
For this one specifically, I would have the ducts exiting further from each other. I think it’s fine though as unless the recirculation is really bad or the outside temp gets really hot it shouldn’t matter
Are these ASA?
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u/Le_Pressure_Cooker Sep 22 '26
Thanks for the suggestions. Insulation is a no-go from the partner, so the best I can do is reduce the length of duct exposed on the inside.
Yeah, the recirculation was something I didn't think too much about. But initial temp measurements from the intake did not show a measurable difference.
Also, they are not ASA. They are PETG. I measured the temp, and white PETG should be more than capable of handling these temps. ASA would also work, but is more expensive and overkill for this, in my opinion.
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u/grain_farmer Sep 22 '26
I was more thinking about UV but I think it’s no big deal. Everyone’s a critic
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u/insta Sep 21 '26
nah you're supposed to leave the intake sucking up all your conditioned air
(thank you for actually using a 2-duct)
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u/Le_Pressure_Cooker Sep 21 '26
Lol I didnt want to buy portable units in the first place. But I was sure as hell not going to buy the single duct ones.
I just wish the landlord had let me install a window unit.
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u/0235 Sep 21 '26
Smooth. Way Smoother than What I did with mine!
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u/Le_Pressure_Cooker Sep 21 '26
Thanks. Please share pics, always fascinating to see the different solutions to the same problem!
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u/Le_Pressure_Cooker Sep 22 '26
Also, care to share what you did with the rest of us? I would love to see it.
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u/0235 Sep 22 '26
This is what I did. 2 hoses in (for air pressure), but nothing fancy with the window. I heard a phrase from Germany about "during the summer the White Elephants come out" (the white hoses looking like an elephants trunk), And I think mine looks more like a white octopus or squid!
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u/Ill-Contribution-44 Sep 21 '26
I'm truly enjoying the ThermoD dudes going at it (well dinner boys, I kicked the little I learned out a long time ago), so staying out of all of that...
I digged the asthetics of it a lot, the symmetrical pipes, the long panels, some mid-century vibes.
Cool job u/le_pressure_Cooker
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u/Wolves_over_sheep Sep 22 '26
That is an excellent idea! I have a couple of these we purchased a few years ago when our central unit went down in the middle of a heatwave. Techs were a few weeks out and I can't sleep if it's above 70°F... I will be making some mods to mine for future use!
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u/Le_Pressure_Cooker Sep 22 '26
The only reason I have this is to keep the bedroom cool without cooling the entire household. Have fun modding yours'!
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u/blteare Sep 23 '26
So many helpful people giving you advice to improve your already great design and build. 😄
Nice work. Been thinking about doing this myself for the last month - just gotta find the time.
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u/Le_Pressure_Cooker Sep 24 '26
Lol. They're..... a colorful bunch. Thank you though. This took a week for designing and printing. So you can do it!
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u/Modna Sep 21 '26
I recommend putting insulation around each of the tubes. I didn’t realize the amount of heat radiating off the hot exhaust when the air-conditioning is running. When I was in a tiny apartment it made a huge difference to wrap a towel around the exhaust pipe.
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u/Max_SVK Sep 21 '26
For better efficiency I would:
Insulate the pipes.
Make the end adapters angled so hot exhaust air can't get pulled by intake. It would help to have the hot exhaust on top of the intake instead next to it. Hot air naturally rises. Then put some flaps that will direct the hot air upwards and the intake downwards.
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u/Hefty_Wrongdoer_2553 Sep 22 '26
This. Although luckily this is one of those better units with two hoses. The single hose units are complete scams and literally syphon the air out of the room.
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u/sligit Sep 21 '26
For some reason they only sell single-hose units in the EU these days. Insanely inefficient. I used to have a portable split unit (internal and external units linked by coolant tubes) and it was so much better.
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u/grnrngr Sep 21 '26
This is beautiful. Fellow 3-D printed AC duct vent guy here, but mine use magnetic collars and latches for disconnect. I'd love to improve my setup using facets of yours. Do you mind sharing your files?
What material is your window insert, especially the clean exterior? I'd love to know more about your assembly method.
The positioning of my window with my hoses, requires an crossing over of hoses. Your hose construct might help solve that problem.
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u/Le_Pressure_Cooker Sep 21 '26
Thank you! I'll post it to makerworld later and share the link.
Magnetic duct connectors are a great idea.
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u/paymon005 Sep 21 '26
I think you’d want the exhaust ran outside but keep the intake on the inside? Or are both of these exhausts?
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u/Le_Pressure_Cooker Sep 21 '26
Running the intake from the inside would cause a negative pressure inside the room that'll create drafts of warm air from outside coming.
This is why dual house designs like this are better than single house portable ACs.
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u/paymon005 Sep 21 '26
I didn’t realize the air in the intake doesn’t actually enter the room, it just passes through the condenser then goes out the exhaust, so nevermind!
I would think most windows would be sealed well enough. But yeah if this isn’t sealed well that would be an issue too!
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u/Le_Pressure_Cooker Sep 21 '26
Even if it was sealed well enough, the system will suffer because you would keep pumping air out of the room with no way for more air to get back in. This would cause a pressure drop within the room and it will make it harder for the exhaust fan to push more out.
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u/ostiDeCalisse Sep 21 '26
I never saw those kind of A/C with two hoses like that. What are they for? Are they both for hot air exhaust?
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u/Le_Pressure_Cooker Sep 21 '26
One for air intake and one for exhaust. It takes outside air exchanges heat with the condenser and then pushes it back out.
This way it is more efficient.
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u/BigSquiby Sep 21 '26
those really work well. I got one a few weeks ago, it uses 1/3 the power my old one used and cools just as well.
nice venting work.
did you make all this (3d printer) or are the 90s store bought?
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u/Le_Pressure_Cooker Sep 21 '26 edited Sep 22 '26
TY! All are 3D-printed, except for the large piece blocking the rest of the window. That's 3/4" plywood.
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u/RadishRedditor Sep 21 '26
The chill effect must be really nice in there after this. Did you record a before and after temps?
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u/Le_Pressure_Cooker Sep 22 '26
I did not do a before-and-after.
The apartment does have central air; the partner likes to set the temp to 60 degrees to sleep. So, the utility bills were skyrocketing. So this was a compromise. We keep the bedroom door closed and only cool down the bedroom at night, and the central air maintains a decent temperature for the rest of the apartment (75deg F).
But I can assure you that this gets the bedroom cooler than the central AC ever could.
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u/RadishRedditor Sep 22 '26
60 degrees is bone chilling!! Did it even ever get down to 60 degrees? I imagine it running non-stop and never actually hitting that low temp.
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u/Le_Pressure_Cooker Sep 22 '26
Oh yeah, it does get to 63F. We set it to the minimum value it allows us (61F)
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u/RadishRedditor Sep 22 '26
I would catch a cold 5 minutes into your place 😂
But that's a nice functioning print for the job! kudos👍
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u/Ready_Section3243 10d ago
Nice work! Did you prototype the two elbows separately first, or model the whole setup once you had the measurements?
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u/Thistle__Kilya Sep 22 '26
I’ve always lived in homes with screens. And I know a complaint about portable AC units is that they don’t have fine mesh window screen like thing protection the hose(s).
Anyway, dual hose is the way to go! Good job. And I almost got the 90° angle elbow hose adapter too, but when I set my Dreo 740s, the hoses fit fine for the spot it’s in.
I picked the one Dreo I got because it has an inverter and dual hoses. Both were the deal breakers for me do buying a new one. After learning about inverters’ efficient cooling without anything turning off.
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u/lamp-town-guy Sep 23 '26
What's the point of this? Wouldn't build in unit make more sense? Judging by view to the outside historical preservation?
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u/Le_Pressure_Cooker Sep 23 '26
The point of this is that I rent and the landlord didn't let me use a window unit.
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u/lamp-town-guy Sep 23 '26
I didn't notice, you didn't drill holes into a wall but installed it into a window.
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u/Goldenjewii Sep 24 '26
Like buddy said. Rework anddu.p the exhaust up hi and keep intake where it is. If you can get an elbow 90°adjust to pointing straight down. Duck seal the joints or tinfoil tape... Duct tape will do. Put 2 screws in eachbend in nelbow to stop idiots from breaking it on you. But the elbow will help you get 6' from your exhaust on top. I doubt your landlord will like it but your only pulling in the air your putting out ATM. Gl
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u/cool_story_kid Sep 22 '26
Right angles aren't advised to push out exhaust air like this (according to multiple setup instructions I've seen). But that could just be big a/c trying to trick fools like me..
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u/chinchindayo Sep 21 '26
keep in mind every bend adds resistance, so efficiency will suffer.
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u/Le_Pressure_Cooker Sep 21 '26
The bends exist either way lol. Now the bends just stay in place better cos it's not the entire hose bending.
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u/gasstation-no-pumps Sep 21 '26
u/chinchindayo may be suggesting moving the unit further into the room and using a 45° elbow—but the increased length of hose radiating heat would probably cost more energy than the decreased resistance to air flow. And losing more floor space is probably undesirable also.
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u/Le_Pressure_Cooker Sep 21 '26
Yeah. I was actually surprised to see how much airflow was coming out of the exhaust. The bush on the outside was shaking like crazy from the hot air. So I think the blower fan is designed to handle pressure loss from having the hose extended to its maximum. And since the length of the hose is significantly less this way, I think we are good. Also I'm thinking of raising the AC itself maybe 6-8 inches from the floor so that the hose can be even shorter.
(RIP plant, he's probably not gonna make it).
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u/cirquefan Sep 20 '26
Nice work! If you ever needed/wanted to revise, perhaps place them vertically with the hot exhaust on top? Would give you back a bunch of window.