The apparatus should consist of a heat exchange unit (possibly as simple as a metallic tube) which allows both air (at atmospheric pressure) and water to flow through it and also allows heat exchange between the apparatus and flowing air or water.
It is suggested that the aperture area be within the range of 0.75 m2 and 1.77 m2(Aperture area is as defined in 3.1.6).
A pipe of inner diameter 8mm and outer diameter 14mm will be provided at the venue for both water and air flow. The pipe provided will be approximately 1.5 m above the floor surface. It is advisable that participants use a flexible inlet pipe with appropriate dimensions to fit in the above mentioned pipe. Apparatus should be equipped with an outlet pipe so that flowing water can be collected in container kept on the ground.
Water should not accumulate or stagnate at any given instant inside the apparatus. Any apparatus found violating this rule will be disqualified.
It is recommended that apparatus should be equipped with a mechanism (manual or autonomous) which aids in setting up the apparatus to maximum possible exposure.
It should be noted that participants are not allowed to manually adjust their apparatus once the competition is declared to have started. However any autonomous system can continue to adjust the apparatus for maximum exposure.