The unit has a heat mode where the thermostat can be adjusted to temperatures between 61 and 77 °F. It operates as a heat pump that basically does reverse air conditioning.
The AC's cooling capacity is a whopping 14 000 BTU, meaning that it can efficiently cool large spaces up to 500 sq. ft. And it can do it rather quickly, if the initial conditions aren’t too drastic.
This air conditioner can be pre-programmed to operate without supervision. You can simply set the desired working intervals, during which it will adjust the ambient temperature to match the pre-set one.
The Whynter ARC-122DHP is efficient in spaces of up to 400 square feet - it offers 12 000 BTU cooling and 10 000 BTU heating output. The angle of the deflector on this unit is adjusted so that the air shoots forward, going up at about 40 degree angle - this way the cool/warm air gets spread evenly around the room.
The ARC-122DHP is one of the quietest portable AC units available - it does not exceed 52 dB, approximately the level of a calm conversation at home. The loudest part is when the compressor cycles on and off, but it is mostly not audible over the fan. However, if installed in the bedroom, it can still wake you up if you're a light sleeper.
This unit self-evaporates most condensate under average conditions, but if it's really humid, an automatic internal condenser pump for continuous drainage kicks in. You can connect the drain tube to the exhaust tube and direct the water outside, or just put a bucket beside the unit and let the water drain there. This way the water tank never gets full, which means that the compressor won't shut off on its own.
The window kit comes in two lengths - 26''-28'' and 36''-38''. It rarely fits the window perfectly, most people need to cut the plank and add air conditioner foam weather stripping, used for window units. The instruction manual doesn't help much, because it's poorly written (lacks some information on how to connect the hose and how to detach connector from the window kit).
When in AC mode, the fan is on continuously, there is no way to set it to turn off automatically after a while. The condenser cycles on and off, but the fan doesn't, and it can emit a high-frequency sound when set on medium or high speed.