Many older systems have had problematic histories due to improper array layouts. Thermal expansion in some systems has caused damage to the piping, while excessive flow rates have led to erosion of the piping in others. A properly laid out array is one that brings the performance of each collector in the array to or above design conditions while maintaining the physical integrity of the fluid circuit. There are a few key areas to pay attention to in laying out the array:
- Keep flow velocities below 5 fps. This means no row longer than eight 4 x 10′ collectors with 1″ headers or twelve collectors with 1.5″ headers.
- Allow for thermal expansion within the array. You should always allow for some ‘swing’ in the joints between the header for the row and the supply and return piping. If you pin the joint then something will fail.
- Plumb the rows in a reverse-return manner or allow some other method of balancing flow within the array.
- Insulate all lines and protect from UV damage with either a latex coating or jacketing.
- Consider installing isolation valves that allow any row to be brought down for service while the remaining rows are allowed to function.