A roof plan is a scaled drawing or diagram of a proposed roof development containing dimensions of the entire roof structure, including shape, size, design and placement of all materials, ventilation, drainage, slopes, valleys and more.
In a "close-coupled" SWH system the storage container is horizontally mounted immediately above the solar collectors on the roof. No pumping is required as the hot water naturally rises into the container through thermosiphon flow. In a "pump-circulated" system the storage container is ground- or floor-mounted and is below the level of the collectors; a circulating pump moves standard water or heat transfer fluid between the container and the collectors.
SWH systems are designed to deliver hot water for most of the year. However, in winter there sometimes may not be enough solar heat gain to deliver sufficient hot water. In this case a gas or electric booster is used to heat the water.