New portable air conditioner already losing steam

[IndyColtsFan]

Yep! that is mine as well

As others have said, the window needs to be sealed.

My house has casement (ie, swing out) windows and I bought the unit for my office, where temperatures can get into the 80s even with my central AC cooling the rest of the house into the low and mid 70s. At first, I built a foam-board insert for the window so I could remove the screen and replace it with the foam board insert which had a hole for the duct hose. That worked, but the foam was just too flimsy and a strong gust really affected it.

So for now, I ordered an extra screen and put my foam insert over the top of that. It is much sturdier but even still, there are gaps that probably need to be sealed. I'm going to build an aluminum frame and have a polycarbonate insert made for it and on the outside-facing side of the frame, I'll put foam tape so when I press it into place, it will hopefully seal everything well.

 

[dave_the_nerd]

Get a window unit. I never had trouble with those.

7,000 BTU was enough to adequately cool a 400sqft studio.

'course, i don't know, maybe you live in Arizona or something.

 

[Hail The Brain Slug]

I have a portable 8k btu AC cooling my 650 sq foot apartment. It was very weak and didn't quite do the job so I went to Lowes and bought some foil lined cotton insulation and insulated the vent ducting, insulated the window seal, and blanketed all my windows. (its been over 100 in the last couple weeks here). Those did the trick, my apartment is regularly around 68 degrees when I have the AC going regardless of how hot it is outside.

 

[Sattern]

I don't think portable air conditioners are meant to be left on for too long, it wouldn't surprise me if they burned out. I'd suggest installing regular air until they revolutionize this technology.

 

[Red Squirrel]

With this type of vented AC unit, even that is a bit undersized. I used one in a 100 sqft office, and it simply couldn't get the temperature down below about 80 when outside was about 95.

This type of unit vents a HUGE amount of hot exhaust through the hose; of course, the air source for this is your already cooled air. The result is that hot, humid air will be sucked in from outside through any crevice and crack. This means you can delete about 50% of the rating, as 50% of the cooled air goes straight out the exhaust and brings in fresh, hot air.

If operated in a sealed room, they will generate a vacuum and any small draught will become a gale. Seal the room too much, and you'll put a lot of pressure on doors and drywall from the vacuum, and you'll stop the thing cooling as it won't be able to pull enough cooling air.

Yep pretty much. I solved that issue with mine but before I did it would actually open the door if it was not latched. Though even with the repairs I made there is still lot of radiant heat generated by the pipe and unit. I insulated mine but it's still not 100% as I had to keep in mind that it's not a permanent install so did not want to start taping up everything. These units are nice for a last resort setup such as crank windows where a window unit wont work and if you plan to eventually get central A/C and don't want to punch a hole through your wall for a through the wall unit or a mini split. If mini splits were not so damn expensive I'd probably go with that though as even once I get central A/C it never hurts to have a complimentary A/C unit for a room you may need it more and they don't require that big of a penetration through the wall. The key to any kind of penetration is to ensure a proper seal. You can't just go punching holes in the vapor barrier like a mad man and not tape it up properly after.

 

[Tiamat]

First off, thank you so much Tiamat for this very well thought out response. Maybe the AT gods bring you much favors. Unfortunately, the '1/3 down the longest wall' doesn't really exist-- my kitchen with the door frame juts outward and there aren't any windows along the way-- I could put the portable AC unit in the kitchen but I cook there, so I'm not sure the oven heat (when it's on) is a good idea. Also, the window that is in the kitchen tends to catch breezes that blow in-- I could probably direct the hot exhaust in a way that this wouldn't be a problem, but I haven't done that yet.

If you have any feedback on the idea, I'd love to hear it!

P.S., I slightly changed the exhaust angle on the window just now, and it seems to be circumventing some of that heat short circuiting you were talking about.

The problem with portable ac units is that much of the fixes for their lack of performance destroys the nature of their portability. If your hot air exhaust line is too long, heat will radiate from the flex tube. If there is any leak from the flex hose, heat leaks back into the room. The actual motor makes heat for your room too. If the duct at the window is not a good seal, any draft from outside will return the hot air back into the room. These ac units suck for electricity costs. You can put it on a timer and have it turn on 30 minutes before you get home and have it cool your computer desk or bed directly if you find it cannot circulate air throughout your room. Also get some good window shades to block out the sun if u don't already have some to minimize heat. With nonideal room geometry and furniture blocking some of the air paths, it is clear that some areas will not receive much cooling at all.

 

[Moonbeam]

The obvious answer is that it has gotten hotter than it was when you bought it. My car AC works fantastic in the winter.

 

[Ichinisan]

I would recommend buying a regular A/C unit and not one that runs on steam.

Came to say this.

 

[TehMac]

Came.

That's so hawt!

Btw guise, thanks for the tips, Ive been sealing my windows as much as I could have and I'm seeing improved results!

Now I just need to figure out how to stop vomiting in the parking lot...

 

[Tsavo]

I don't think portable air conditioners are meant to be left on for too long, it wouldn't surprise me if they burned out. I'd suggest installing regular air until they revolutionize this technology.

I have a portable something or other that gets really hot if left running for more than 15 minutes at a time. I took off the cover to the compressor, and that helped a bit, but it would still occasionally SCRAM and not start until cool.

 

[TehMac]

I have a portable something or other that gets really hot if left running for more than 15 minutes at a time. I took off the cover to the compressor, and that helped a bit, but it would still occasionally SCRAM and not start until cool.

weird, I haven't had that problem, although I still can't seal up the window all the way (improv'ing it with some of the packing styrofoam and the retard piece of plastic honeywell sends you for the task.

I did start hanging a towel on the blinds covering the window that gets hit hardest by the sun. Probably reduced the temp by 2* but a good start

 

[Red Squirrel]

Yeah my unit is actually cold to the touch except the compressor area is a bit warm but not that warm.

To seal it, this is what I did:



That piece of plywood is cut to fit where the screen goes. I then put weather stripping on the other side so it goes up against the frame and provides a more or less air tight seal. When I cut this I did not have the proper tools such as a straight edge or circular saw so it was actually cut with a jig saw so it's not perfect but it works fairly well. This is a temp solution till I get central air so have not bothered to put foam insulation or paint it. The insulated pipe is the hot air exhaust, the metal pipe is the outside air intake. I could technically insulate that too but never bothered.

My system is not 100% air tight but it works fairly well compared to running it stock. My windows are crank windows so I had to use the plywood setup, there was not really any other way to do it.

This is all a temp solution anyway. Whenever I decide to get central AC I will probably store this unit, and when it comes time to finish my garage and insulate/seal it I'll probably install it in the garage as the main source of heat and cooling. It has a heat pump mode as well which throws off a decent amount of heat.