Overview
System type: Self-pumped closed-loop antifreeze
Location: Washington, DC
Solar resource: 4.6 average daily peak sun-hours
Production: 1,231 kBtu per month, average
Domestic hot water produced annually (estimated): 70%
Solar Equipment
Collector: Alternative Energy Technologies AE-40, 4 x 10 ft.
Collector installation: Roof-mounted, 45° tilt
Heat-transfer fluid: 45% propylene glycol & 55% water: rated to -22°F
Storage
Domestic hot water storage tank: Bradford White, 80 gal.; with electric backup
Performance Monitoring
Thermometer: Pasco, dial; maximum 240°F
Pressure gauge: Ashcroft, dial; range: 28 mm Hg (negative pressure) to 30 psi (positive pressure)
Pressure & temperature gauge: P&T dial gauge in brass well