Moisture in air will condense on an evaporator surface over a wide range of operating conditions. Evaporators can be positioned horizontally or vertically or on any angle in between. Tubes must be arranged so that refrigerant migration and drainage can occur. A frequent problem is that drains are not located properly. They may be provided at different locations depending on the exchanger's orientation. A vertically mounted coil with tubes in the horizontal plane often has its drain located in the evaporator's lower side channel. This is ideal from a drainage point of view. The drawback is that if the drain should plug for any reason, there may be no reasonable way to clean it. In some buildings evaporators are located above the ceiling. The same problem can occur if the coil is installed horizontally. An evaporator drip pan beneath the coil has a drain at its center. When it is plugged water will collect in the pan and eventually spill, staining anything beneath it. In many applications no reasonable way for unplugging this drain is provided.