>>105655444>The thing is that dual pipe has the bonus of not actually dragging in outside air unnecessarily.No it's not. A/Cs have two main parts - the condenser (hot part) and evaporator (cold part, aka "the coil"). The compressor compresses the refrigerant causing it to become a liquid, which then flows through the evaporator where it is exposed to the hot air in the room. As the refrigerant passes through the evaporator it...evaporates, turning back into a gas, and in doing so takes the heat from the air with it as it continues flowing to the condenser.
A fan cools the condenser, releasing the heat that was inside into the air outside, prior to the cycle repeating - where the refrigerate hits the compressor again and goes from gas to liquid.
Now you can see what a dual-hose unit is actually doing. It is not sucking air in from outside and releasing it into your room, it is using the outside air to cool the condenser, and then immediately exhausts it back out the other tube. The air flowing through a dual-hose unit never leaves the inside of the unit.
A single-hose unit will be drawing the air inside the house to cool the condenser, blowing it outside. This is why single-hose units fail.