Two stage evaporative coolers are basically new addition to the household of alternate cooling appliances. The advantage 2 stage coolers have over conventional, single stage models is the generation of air which is cool with 10%-30 % much less humidity (depending on your climate).
The steps of a 2 point cooler are called "indirect" best portable ac for camping (try %domain_as_name%) the first point, and "direct" for the next stage.

A conventional swamp cooler, by the nature of its, gives additional moisture to the air it cools. To address this, a pre cooling, or perhaps indirect stage, was added.
In the indirect stage, warm, air which is dry is pre-cooled by passing by having a heat exchanger cooled by evaporation on the outside. As the air supply to the next stage evaporator is pre cooled, the end result is cool air with 50% 70 % relative humidity compared to eighty % humidity from a conventional individual stage cooler.
An extra advantage of first phase pre cooling and decreased humidity is extending the product's usefulness into hotter and many more humid conditions.
2 stage evaporative coolers are most often installed right to an outside wall and at ground level supported by a tiny concrete pad. The devices need a 115 VAC electrical connection, a source water connection as well as, in case they've a water bleed off mechanism to minimize mineral deposits, a way for water disposal.
The largest devices enjoy a cooling capacity of 3 tons, a source air flow of 1,400+ cubic feet a minute and take in around 3 gallons of water every hour. This's enough cooling capacity for up to 1,700 square feet of living room.
Since a two stage evaporative cooler brings exterior air into the home in a relatively high rate and doesn't recycle indoor air, good air pressure builds up inside the home. In order for the system to work effectively, the stress should be relieved by opening a handful of windows a couple of inches, or perhaps putting in an exhaust duct or perhaps pressure operated damper in the attic or perhaps an outside wall.