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Modifying window AC units for in-room operation?

G

Guest

Have any of you modified a window A/C unit to operate as a "portable" unit, to be run indoors without sticking out of a window? They're considerably cheaper than the portable units, and I don't really see any real advantages of the portables (unless you need to move it around, which I don't).

Wouldn't it be possible to simply build an enclosure for the unit, and run ducting to exhaust / draw air to / from the outside? Seems quite easy and straight-forward, but I'm asking because just about every single "money saving" DIY project I've done (which initially seemed like a great idea) eventually ended up costing more and performing worse than the more expensive, pre-built option. So in preparation / research for this project, I have a few questions:

  • How do most low-end (5-6k BTU, 110/120V) window A/C units work? Do they draw in and exhaust air from the outside? Or does it draw air in from the inside? In other words, is it more or less operationally equivalent to a dual-house portable unit? Home Depot didn't have any open units to check out, and I've never really paid much attention to them before today... A quick glance seems to indicate that the hot air is drawn from the inside of the room through the front (user control side), exhausted out the back, and the cooled air also through the front via different set of vents / grille.
  • How do the "analog" controls work (Lo, Med, Hi, etc)? Are they controlled by a thermostat (i.e., Lo = 80F, Med = 70F, ...)? Those seem a bit cheaper than the ones with the digital LEDs. I've also noticed that the portable units have dehumidifying capability... how about the window units?
  • Would this generate too much noise for an indoor, apartment situation? Are the portable ones any quieter? I'm trying to run this in a small studio apartment.
 
rasputen

rasputen

Member
Yes! I have 2 running inside the "Attic Igloo".

They have an enclousure built around the back side (condenser) that is extracted up to my hot plenum and extracted by a roof top exhaust fan. NOTE: The air is taken near the floor and extracted UP to the roof area...using CONVECTION along with a 500 CFM fan. The system works fine. I have utilized the "Hot Plenum"/extraction fan as an general extractor and exhaust the flower room as well as the veg room and the heat of the AC's.

The system MUST extract all the heat generated by the AC!

Window AC units just recirculate the inside air and ONLY the heat is pushed out the back. What I mean is the heat is remooved internally by the freon and pumped out the back but the air is never moved from inside to outside or outside to inside.

The 8000 BTU GE AC I have is very quite, the 5000 BTU unit is a noise maker.
 
J

JDOG6000

Active member
Veteran
A friend of mine borrowed my AC unit once.
He fastened a rubber made tub around the ac with the back cut off.
The back was sealed(sort of) to the open window. And sealed shut.
It worked to my suprise.
 
BCboy

BCboy

New member
I had a setup that worked fine but I was scared away by the amount of heat the a/c produces. I had 6" 449cfm fan sucking the air through my contraption. Being in an apartment I decided to err on the side of caution... the last thing i need is smoke or fire. I going to get a portable instead. Here are some pics.


Cat helping

Styrofoam spacers for air channel

Rear vent

Used silicon to stick it together (stinky)

Exhaust hose installed

All installed... top 6" fan for lights bottom venting a/c
 
billbob

billbob

Member
BCboy- I like your invention! The exaust is a bit small i think though. Probably hard on the AC.

Go to a metal shop that makes Ducting and have them make a piece out of sheet metal that will screw on the back of the AC (or make your own if skilled). The sheet metal piece should have a 12" vent (elbow if going up) that once you connect ducting will have an axial fan at the other end (10" works well). You will need to cut a hole to vent the ducting out in the ceiling or????. The vents of the AC will be open on the outside of your room and the exaust exausted. Will work great, just keep the fresh air tab on the AC closed if you are running a sealed room. The metal shop should cost you less than $40 and be well worth it. You can make one out anything (box, plastic tub, etc.) but the metal will be the safest. A box will get wet and crumble, Plastic can melt (hot air exausting), etc. The metal will last the life of the AC.
 
BCboy

BCboy

New member
Metal is a great idea. I decided on the 6" duct and fan for the 10,000btu a/c because the 12,000btu portable I was looking at only had 5" intake/exhaust thus i figured 6" should be fine. To change to a 10" fan now would cost me another $200+cnd. although i might bite my tongue and do it lol. I would have bought a portable in the first place but I wanted the a/c to turn on /off using a computer controlled relay. I couldn't find a portable that would auto reset after a power interruption. I have however found a thread where a guy talks about easily rewiring a portable a\c to auto reset... waiting for him to post the how too. Thanks for the ideas.
 
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billbob

billbob

Member
10" axial fan from grainger.commm about $70us. The fan does not need to be a heavy duty blower. Just so that it keeps the air moving. Also depends how far the ducting runs.
 
clowntown

clowntown

Active member
Veteran
I never thought about needing a fan to move the exhaust air. I can just picture the unforseen parts / costs stacking up and this whole thing blowing up in my face (figuratively; although wouldn't be surprised if literally) yet again! For some reason somehow I considered myself some DIY superstar with these ideas, but quickly found out that I suck!

Thanks all for the responses. I think I'll just bite the bullet and go for the portable. *cringe* That way I'm sure not to have any regrets or have something go horribly wrong (again).
 
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clowntown

clowntown

Active member
Veteran
Yeah, that's what I plan on getting now... a portable AC. I thought I would just try and save a little money by doing a DIY project, but with fan (which I didn't even take into consideration when I originally posted), fittings, etc, it just doesn't seem to be worth saving a little money with the risk of it not working too well, being ugly / in the way of things, etc.
 
Buzzsmirk!

Buzzsmirk!

Active member
portables are the way to go for stealth and functionality!
make sure u get a TWO HOSE design or u will have to deal with some stank odor issues!!in addition to your current problems that tax ur budget
good luck
BUZZ!
 
G

Guest

Buzz how does the dual hose help with stank issues?I hope I'm looking at this correctly for my co2's sake.A single hose unit simply has an exhaust hose that's normally run up through the ceiling to an attic,the intake is inside the unit itself.With the dual hose again the exhaust is run through to the attic but the intake hose is put through a wall to another room.The only difference here is with one unit the intake is in the same room,with the dual hose the intake is in an adjoining room.Thats how I figured these things worked,thats why I got one for a sealed room with co2,so as not to take the co2 through the unit and out through the exhaust hose.Either way the exhaust is the exhaust no matter the intake,so how does a dual hose help with stank?Maybe I have been looking at this all wrong.
 
stonewall

stonewall

Active member
I believe you have it figured correctly SKELETOR.


Here are a couple of pics of my 5K btu modified window unit. It is a bit undersized for 2K lof light, but only struggles on the hottest days. Otherwise it works great. The key to modifying a window unit with out affecting its performance is to make sure you give the condenser plenty of moving air. Make sure not to cover the inlet louvers with your exhaust box or duct tape. Make the box so there is atleast 6 inches between the back of the coil and the box wall. Add a fan to exhaust the box, mine is 250 cfm, this I believe is a minimum for 5K btu. Luckily mine has a slinger wheel on the condeser fan blade, so all the condensate water from the evaporator is used in the process, otherwise you will have to collect it someway.


 
Buzzsmirk!

Buzzsmirk!

Active member
SKELETOR said:
Buzz how does the dual hose help with stank exhaust is the exhaust no matter the intake,so how does a dual hose help with stank?Maybe I have been looking at this all wrong.
Click to expand...

in theory the single hose draws air from the cooled space(bloom area) thru the condenser coil and out the hose. this config has obvious stink/odor hazards becuzz ur pulling air from the space and putting it outside
some folks run this airstream thru a scrubber but if ur unit dispenses of the water condensate from the evaporater pan onto/into the condenser airstream
your carbon's "pores" will clog and hurt the scrubbers performance.

the TWO hose config (in theory) has the simalar benifit of aircooled lights using the outside air source to "cool" the unit you eliminate the "stink/stank"
issue by design.
however i used to use a two hose portable and it sucked my co2 and i supose stank odor too.
i now use a small split system and have no problems with odor or co2 loss
BUZZ!
 
G

Guest

I see what you're sayin,I have the hose run through the wall to the "cure room" so it only transfers smell to the attic when I have something hangin,which is like all the time lol.I really havent had to many odor issues,and I plan on having zero here shortly I already have my vaportek optimum 4000 in the box I'm just waiting for the flowering plants to stank a bit.How did you lose co2 using a dual hose system?You didnt have the intake hose in the same room as the plants and unit did you?
 
Buzzsmirk!

Buzzsmirk!

Active member
SKELETOR said:
I see what you're sayin,.How did you lose co2 using a dual hose system?You didnt have the intake hose in the same room as the plants and unit did you?
Click to expand...

i am geussin that it still was able to "mix" within the unit's enclosure i took it apart and was not pleased with the way they built it.
so i bought a small split the next week and have never looked back.
BUZZ!
 
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