Not up to the job

I was very dissatisfied with my purchase of a SUNPENTOWN WA-1010H portable air conditioner. The cooling rating of 10,000 Btu/hr is misleading or wrong. We purchased it to cool a bedroom of only 150 sq. ft. and on a hot day in the mid 90's it will only cool the room to the high 70's or low 80's, which is not comfortable enough for sleeping. This room is well insulated and the unit is correctly installed with an exhaust port to the outside. We have a Whirlpool window mounted unit in the living room downstairs which is only rated at 8,000 btu/hr and on the same day it will easily cool a room of 300 sq. ft to the hi 60's or low 70's.

Also my wife thought it too noisy for sleeping.

The cooling rating is misleading in some way. I'm trying to understand were I went wrong. We live in a very dry climate, avg. humidity 24% in summer, whereas the spec of 10k btu/hr is for 81% humidity. Maybe something in its design requires the higher humidity to operate at full capacity. Also this unit has a single exhaust line for the hot air. This means it creates negative pressure in the room which draws in more hot air that then needs to be cooled. This must effectively cut its real cooling capacity. Probably should have bought a dual tube unit which draws air from ouside then exhaust heated air out. Problem is this makes the unit less easy to install and move.

Additionally I find that NewEgg will not accept a return, even with a 15% restocking fee ( my paying shipping each way). So I am stuck with a $500 unit that will not do the job for which it was purchased.