Why do "portable" air conditioners get a bad rap?

[StaggeringGoat]

I'm trying to cool my office in my shop as cheaply as possible. (about 300 sq ft) I've thought about installing a window and an A/C unit into the wall between the office and shop, but I don't really like that. (more heat in the shop) I have no other walls/windows/doors where I can install an air conditioner.

Thus, that leads me to the "portable" air conditioner. I don't know much about them, but I do know people are always complaining that they don't work very well.

Question is...why? If I got a 10k BTU portable air conditioner how would it be different from a 10k BTU window unit? I would have to cut a small hole in my office for the hot air vent, but I think I could direct that outside through my shop quite easily.

 

[Gary S]

I'm no expert on A/C. I have a window unit in my garage and love it. I know of no reason a portable unit shoudn't work just as good and make you just as happy.

 

[RKA]

The reason they get a bad wrap is they are exhausting hot air. Where do you think the make up air comes from? They make 2 tube units to get around this issue.

 

[pseudorealityx]

...in addition to what RKA said, the 2 tube versions are crappy because now you're trying to duct hot air out somewhere, and you're losing that heat to the space the whole time. In addition, you're limiting airflow to the condensing side.

Think of a portable A/C like a window A/C where the outside part is a box, and you're trying to bring outside air into the box, heat it up, and then pump it back outside. It's just a crappy way to do things.

 

[JimVonBaden]

...in addition to what RKA said, the 2 tube versions are crappy because now you're trying to duct hot air out somewhere, and you're losing that heat to the space the whole time. In addition, you're limiting airflow to the condensing side.

Think of a portable A/C like a window A/C where the outside part is a box, and you're trying to bring outside air into the box, heat it up, and then pump it back outside. It's just a crappy way to do things.

But the window air works pretty well, so I don't get the problem with the two tube portables.

Jim

 

[mayday0017]

We used a portable at my last job to keep the calibration room at a set temp. You could walk in there any time and it was 68 degree's room was about 15x15. That thing worked perfect year round in the wonderful Texas heat...

 

[pseudorealityx]

But the window air works pretty well, so I don't get the problem with the two tube portables.

Jim

You know how a dog pants to get rid of heat?

Now imagine that instead of 'regular' panting, each time the dog breathes in, he has to breathe through a straw. Then he had to blow out of another straw.

 

[guy48065]

Lot of compromises in portable AC units. The 1-hose units take the conditioned room air & flow it over the hot condenser, then up the hose & out the window. Disadvantage is you're using some of the cool air you just paid $$ to treat. 2-hose units take outside air in & flow it over the condenser & out the other hose. Is it more efficient to use hot outside air to cool a hot condenser--or to use conditioned cooler air to do the job? I don't know but I bought the best-rated (Friedrich) 2-hose unit to cool my 600SF cottage and it doesn't do as good a job as the window unit in my 800SF workshop. Noisier, too. It takes a long time to drop the inside temp, then runs constantly on a hot day trying to keep up. If your room is well insulated & you don't expect to hang meat in there you might find it adequate.

 

[SiGmA_X]

If you don't have an outside wall that you can pop a hole in and mount a through-wall or window (as a through-wall) I suggest a 2 hose. Buy some insulated duct cover from HomeDepot/etc and install on the exhaust hose, and have at it. If you have a long run, perhaps install a duct fan. They work, they just are less efficient than a window or through wall (or mini split by a long shot) due to the air flow over condenser. As guy48065 said - they don't do as good of a job as a window, and are louder due to the fan/ducting. But if its your only option, its a damn good option.

Maybe you could install a through wall or window unit through the wall, and then put a duct on the exhaust off the condenser? IIRC the intakes are on the wall/window-side (comes in 3 ways usually) and then the exhaust is straight out the back. Take some sheetmetal, cut up a duct, rivet it to the back of the AC unit, tape it up, and run a 6-8" duct out of the building, with a booster fan to cycle on with the AC unit. That could work and perhaps be better than a portable, and for damn sure cheaper than a 2 hose. Those things aren't cheap.

 

[2Tailfins]

I have a small home in Las Vegas (The Hottest place on earth) and our local HOA has kittens if you have the wrong window coverings so a window a/c is out of the question for my garage- I think a portable unit is all I can use- Any suggestions for a unit to cool a 20'x20 garage?

 

[Warrenator]

I've owned two of the portable units, neither one was worth a darn. Also they make such a racket. I currently use (in my master bedroom) what I call "Redneck Central Air" which is a regular Sharp window unit (8000 BTU I think) with ductwork taped to the front so I can attach 2 of those floppy 6" insulated ducts, which I then tee into the regular ductwork for my heater. The window unit sits outside under the deck and I turn it on with the convenient remote that came with the window unit. IT WORKS GREAT! And is very quiet inside the bedroom. Total expenditure $200. Costs maybe $10 a month to run it continuously because Sharp makes a pretty good window unit.

I did spray some of the Great Stuff! insulating foam on the ductwork where it was sweating. Also, I put round foam plugs in the tees where my flexible ducts join the house's heater ducts, and slide them to either leg of the tee for winter/summer changeover.

We can't have a window unit in the bedroom because that side of the house has neighbors who occasionally berate each other loudly, and you could hear everything.

 

[bobadame]

For every cubic foot of hot air that exits the unit, there is an equal cubic foot of air that enters the room. What is the temperature of that air? It's a bit like a dog chasing it's tail.

 

[2Tailfins]

I've owned two of the portable units, neither one was worth a darn. Also they make such a racket. I currently use (in my master bedroom) what I call "Redneck Central Air" which is a regular Sharp window unit (8000 BTU I think) with ductwork taped to the front so I can attach 2 of those floppy 6" insulated ducts, which I then tee into the regular ductwork for my heater. The window unit sits outside under the deck and I turn it on with the convenient remote that came with the window unit. IT WORKS GREAT! And is very quiet inside the bedroom. Total expenditure $200. Costs maybe $10 a month to run it continuously because Sharp makes a pretty good window unit.

I did spray some of the Great Stuff! insulating foam on the ductwork where it was sweating. Also, I put round foam plugs in the tees where my flexible ducts join the house's heater ducts, and slide them to either leg of the tee for winter/summer changeover.

We can't have a window unit in the bedroom because that side of the house has neighbors who occasionally berate each other loudly, and you could hear everything.

You know thats a good idea!- Instead of the portable unit- Just use a good window unit- in another location and duct it to the area-that gets around the whole HOA problem

 

[carhunter]

OP, I had a shop setup similar to yours with an enclosed office within the work area. We installed a window unit through the wall about 6' up and it worked great. Didn't even notice the exhaust air as it exited into the shop.

We also had 12 or 14' ceilings in the main building which probably helped.

 

[pseudorealityx]

You know thats a good idea!- Instead of the portable unit- Just use a good window unit- in another location and duct it to the area-that gets around the whole HOA problem

Be careful because window units don't have the static pressure to push much through ductwork. If you block it off enough, you'll end up freezing the coil. Same idea as if you let the filter get too nasty. You drive down the airflow, coil gets colder and colder, etc.

 

[gatchel]

I have a small home in Las Vegas (The Hottest place on earth) and our local HOA has kittens if you have the wrong window coverings so a window a/c is out of the question for my garage- I think a portable unit is all I can use- Any suggestions for a unit to cool a 20'x20 garage?

HOA...Time to move...

 

[Sp2Pilot]

Warrenator,
You have any pics of your setup? I'm also in Vegas and am looking for cooling solutions. I've got 910 sq ft that I need to cool, and I dunno if I want to mount something on the wall.

 

[Mike007]

I had no idea they make 1 pipe portable units.

That is really a stupid design.

 

[RKA]

I was in a sandwich shop in central NJ yesterday afternoon and noticed there was a lot of air moving around (along with the noise that goes with it). I looked around and found a mini split on a back wall, which by all accounts should have been able to cool the shop on it's own. But evidentally it was not operating efficiently, so the owner added a portable AC (1 pipe as far as I could see) on the other side and two high CFM fans in front of each of the AC units. I wanted to say something then decided to keep my mouth shut. The point is...as long as it's cheap enough and you can feel cold(er) air coming out of the vents, people will buy it without thinking about efficiency, running costs or cleaning the filters on the units they already own!

 

[guy48065]

There's a nice little bar up by my cottage where I like to wheel in during a hot day of trail riding for a couple cold ones. The place WAS sometimes objectionably cold but now under new owners it's hot & stuffy. The whole seating area is now "cooled" with a single portable 1-hose unit

I need to find a new watering hole.

 

[StaggeringGoat]

I've owned two of the portable units, neither one was worth a darn. Also they make such a racket. I currently use (in my master bedroom) what I call "Redneck Central Air" which is a regular Sharp window unit (8000 BTU I think) with ductwork taped to the front so I can attach 2 of those floppy 6" insulated ducts, which I then tee into the regular ductwork for my heater. The window unit sits outside under the deck and I turn it on with the convenient remote that came with the window unit. IT WORKS GREAT! And is very quiet inside the bedroom. Total expenditure $200. Costs maybe $10 a month to run it continuously because Sharp makes a pretty good window unit.

I did spray some of the Great Stuff! insulating foam on the ductwork where it was sweating. Also, I put round foam plugs in the tees where my flexible ducts join the house's heater ducts, and slide them to either leg of the tee for winter/summer changeover.

We can't have a window unit in the bedroom because that side of the house has neighbors who occasionally berate each other loudly, and you could hear everything.

I like this idea! I too would love to see some pics if you have any. Did you have to install any kind of booster fan in the ductwork, or does the A/C fan do all the work?

I could mount the A/C unit right next to my roll up door in the shop, which is usually open when it's hot. I'd much rather cut a small duct size hole in the wall than one big enough for an A/C.

 

[Warrenator]

Thanks SP2Pilot, StaggeringGoat, no pics of the "Redneck Central Air" as I just started a trip and won't be home for a while, but it's really easy - I bought 2 rectangular "register box" ducts that transitioned into 6" round outlets. They were about the same size as the front of the AC unit if they were taped together side by side. I got busy with the tinships and silver foil tape and taped them to the front of the window unit I bought. Now I have a window unit with 2 round metal outlets instead of the wide plastic front. I did not block off the controls or the air inlet.

I sprayed a thin layer of insulating foam onto the metal ductwork so it wouldn't sweat. Then just layed a few pieces of tinfoil on top of that to keep it looking nice, more silver tape. Connect 2 long pieces (10', 25') of Masterflow insulated flexible duct to the outlets then connected them to the house ducts. Did not add any duct booster fans, they weren't needed, although you can get them from Amazon for $15 each. The A/C unit sits outside on a shelf, it is turned on and off with the remote control from the deck.

Obviously the thermostat senses the outside temperature so it will not turn off automatically, my wife likes to sleep in a 65 degree room so I just let it run. The coldest it has gotten our 18' X 15' bedroom is 64 degrees, and this system does not recirculate the air, just continuously adds cold air, so the dogs will congregate at the doorways where the cold air seeps out. Please try not to step on the dogs. On very hot days (95 degrees is about as hot as it gets where I live) the system keeps it at 74 degrees.

If you have any questions shoot me a PM. This is a fun "Well that looks close enough" sort of back of the envelope engineering project, and if it doesn't work at all you could always throw it all away and only be out $300, the window units and ductwork are pretty cheap. Walk down the aisle where the A/C ductwork lives at your local hardware s megastore and get some ideas ---- one big 12" duct might work better for you than 2 6", etc.

 

[StaggeringGoat]

On very hot days (95 degrees is about as hot as it gets where I live) the system keeps it at 74 degrees.

Very good to know. I vaguely thought of hacking up a window unit before but wasn't sure how well it would work. About the same temps here (well, it's 100 today but that's really rare) and mostly in the low 80s. I can probably get an ugly used A/C on craigslist cheap...

 

[Kevin C]

Living in Portland OR I dont really need AC all that often. I have three units. One is a 8000 BTU window unit in the bedroom. Another is a 10,000 BTU Maytag portable i have in the office. The office is 12 x 14 and the portable unit keeps it nice and cool, despite us having one of our rare hot days ( 100°f out).

The garage unit is a 13,000 BTU portable. Since the garage isn't insulated yet and I dont have the eve vents isolated its not going to keep very cool. The LG unit throws enough cool air towards you so you can work. After an hour of being on it dropped the temp 6 degrees in a 625 sq foot shop. I suppose it helps that all the air leaks are up high and cool air settles.

Both of my portables are very quite. On the older GE unit I did put some dynamat in it to deaden vibrations. The LG was very quite out of the box. I got the GE unit for short money, all it needed was a new bearing on the fan.

They are not perfect, but for some situations they get the job done. In the case of my office the large casement window wont take a AC unit, so a portable is fine. For the shop I just aim it where I'm working and its great.

Typically I use the AC unit less than 20 days a year.

 

[Dick in Wisconsin]

We used a portable at my last job to keep the calibration room at a set temp. You could walk in there any time and it was 68 degree's room was about 15x15. That thing worked perfect year round in the wonderful Texas heat...

How did they get rid of the waste heat? out to the air? or water?

 

[StaggeringGoat]

Well, I did a little experiment tonight and duct taped a bathroom vent fan to the cold air output of a 5000 BTU window A/C. With 80 degree air in I got 55 degrees out of the hose. (and that was with a bunch of leaks) Not sure if the 5k BTU would be enough for my office, but this is definately the way I want to do it....

 

[ejmick]

I had to weigh in on this because every year I struggle to decide whether or not this is the year to move away from my portables.....
I have used two portable AC's to cool my house for the last 7 years and they have worked fine. I have one in the living room area and one in a bedroom, and together they keep the upstairs area of our 1500 sq ft rambler cool enough.
The two reasons I went this route is because of the options I had with my budget at the time:
1. Adding ductwork throughout the house with traditional forced-air furnace w/central air= ~$10k. Not in the budget.
2. Add a dual zone mini-split system ~$3k (DIY install). Not outrageous, but still pricey.
3. Purchase two portable 12k BTU AC units for a total of ~$650. Good enough.

Couldn't use window units because my house has the horizontal slider windows, and narrow window AC units designed for these windows double the price of a regular window unit for some silly reason...
I like the fact that during periods of cool weather I can wheel them away and store them in about 3 minutes, and I don't have the ugly boxes hanging out of my windows and taking up the outside view all summer. BUT, they are noisier, they are less efficient, and they do not cool as quickly as a window unit. In the future, I would like to budget for a mini-split system with a heat pump as I think this would be the best option to supplement my electric heat, but for now, I'll probably just wait at least until one of the portables dies.

 

[theoldwizard1]

In the future, I would like to budget for a mini-split system with a heat pump as I think this would be the best option to supplement my electric heat, ...

This solution could actually save you quite a bit on your electric bill !

 

[5lima30]

They get a bad rap because they don't work well!

 

[jeanjean]

Lot of compromises in portable AC units. The 1-hose units take the conditioned room air & flow it over the hot condenser, then up the hose & out the window. Disadvantage is you're using some of the cool air you just paid $$ to treat. 2-hose units take outside air in & flow it over the condenser & out the other hose. Is it more efficient to use hot outside air to cool a hot condenser--or to use conditioned cooler air to do the job? I don't know but I bought the best-rated (Friedrich) 2-hose unit to cool my 600SF cottage and it doesn't do as good a job as the window unit in my 800SF workshop. Noisier, too. It takes a long time to drop the inside temp, then runs constantly on a hot day trying to keep up. If your room is well insulated & you don't expect to hang meat in there you might find it adequate.

That's right, the advantage of a portable air conditioner over other air conditioners is that it is easy to move. But considering its size, it does not necessarily have all the advantages of ordinary air conditioning. For example, it will be more noisy, and cooling will take longer. These defects are being overcome. In short, portable air conditioners can now be made almost as good as ordinary air conditioners. In many review article of portable air conditioners, you can see its progress very well.

 

[Marctrees]

We used a portable at my last job to keep the calibration room at a set temp. You could walk in there any time and it was 68 degree's room was about 15x15. That thing worked perfect year round in the wonderful Texas heat...

But continue and tell the rest of the story - The Calibration room was WITHIN and surrounded by a larger AC'd building so the load was quite small.

That's how the portable was able to do that.

Marc