NEX ARC-1030WN Portable Air Conditioner

Get a dual hose. Home Depot had a nice Whynter one on sale, for like $389 which is a dual hose which means it takes air from outside and not inside and is far far more efficient. So far, so good. It blows so cold I had to cover up. Edit: link here https://www.homedepot.com/p/Whynter-NEX-10-000-BTU-12-000-BTU-ASHRAE-Portable-Air-Conditioner-Cools-500-Sq-Ft-with-Dehumidifier-Wifi-Enabled-in-White-ARC-1030WN/318926897

I have whynter portable two duct large size, it's noisy but cools well. I would never buy a single duct portable, they pull their coil cooling air from the room, so every other room gets hot air pulled in. No bueno.

If you have the money, buy a dual hose Whynter portable AC. Otherwise - the design and construction of single hose units is such that you won’t be able to get it to not pull vacuum, even by adding a second hose to provide it with outside air. There will be leakage inside the unit itself that will prevent you from getting a perfect loop from outside to outside. But that’s still going to be much more effective than running it with the stock single hose, so it’s worth doing, and will be your best short term solution if money is tight.

I have a whynter dual hose and it has worked for multiple years. Sort of expensive, but efficient and not very loud.

The 12K BTU portable units work fine for even a large bedroom. I have three, all Whynter two hose. One even keeps a 600 sf finished attic with seemingly no insulation in the roof at an okay temperature on hot days. When it is over 100F out, it struggles but still the attic is tolerable if not ideal.

Had a wynter dual hose on my sunroom last summer (250sqft, all window, no significant insulation) and it handled the space very well. It didn’t have an inverter, was only 12k BTU, so my expectation is the zafro will absolutely crush it. The inverter is also significantly more quiet, so if you use in bedroom, it may be a great option.

I’ve got two Whynter dual hose portable ACs and they work great for me. There is a good comparison sheet on the ‘Air Conditioner Lab’ website, which covers all brands and models. I used this to compare Whynter models and get the right coverage area, BTU etc.