Design Package Review and Pre-Installation Planning
This domain tests whether you can read a solar thermal design package critically before installation: collector and system ratings, load and storage sizing, freeze protection, expansion control, pipe sizing, pump head, controls, and permit/structural documentation.
Ratings and sizing
SRCC OG-100 certifies individual collectors; OG-300 certifies complete factory-built systems. Check collector area against the design load, and for domestic hot water verify storage near 1.5–2 gal per ft² of collector. Pool systems normally use no storage tank; the pool is the storage. Confirm design flow near 0.05 gpm/ft² and a pipe size that keeps velocity reasonable.
Freeze, pressure, and expansion
The package must state freeze protection: closed-loop glycol with concentration rated below the design low temperature, drainback, or another listed method. Verify a pressure-relief valve, expansion tank, check valve, vacuum relief, air elimination, isolation and drain valves, and a tempering valve on potable output. Expansion-tank precharge and volume must match loop volume and maximum temperature.
Controls and documentation
Confirm sensor locations, ΔT setpoints, freeze-protection logic, pump relay, and electrical disconnect. Check permits, structural calculations, wind/seismic design, and manufacturer installation manuals.
Worked example
A package specifies 64 ft² of collector, an 80-gal tank, 30% propylene glycol, a 2-gal expansion tank, and a 150-psi relief valve. The storage ratio is 1.25 gal/ft²-acceptable. The reviewer still checks that 30% glycol protects to the local design low and that the expansion tank is sized for the full loop volume.
Traps
Mistaking OG-100 for a whole-system rating; accepting a package with no vacuum relief; undersized expansion tank; no tempering valve; ignoring design flow.