Solar water heating


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Solar water heating

  1. 1. Solar Water Heating Jack Cowan Cowanhouse June 27, 2013
  2. 2. Objective: to provide a framework for determining solar thermal viability
  3. 3. Solar Water Heating Systems (Solar Thermal Systems) • Largest application is swimming pool heaters • Black box collector first patented in 1891 Integral Collector Storage (ICS) (also Batch) • Other collectors include flat plate and evacuated tube • Systems are either active or passive, direct or indirect • Expensive, but nearly free operation and most environmentally friendly
  4. 4. Batch Heater System • Source Arizona Solar Center
  5. 5. Closed loop drainback system • source Arizona Solar Center
  6. 6. Closed loop antifreeze heat exchanger system • source Arizona Solar Center
  7. 7. Prerequisites to Solar Thermal • Reduce hot water waste – conservation 1st • Evaluate your hot water needs • Compare solar to other water heating technologies
  8. 8. Reduce Hot Water Waste • Repair leaky faucets • Insulate pipes where possible • Use high efficiency shower heads and aerators • Select most efficient appliances that use water • Optimize hot water distribution (with new construction design) • Improve water use behavior
  9. 9. Evaluate Your Water Heating Needs
  10. 10. What can you tell about water heating requirements from utility billing data if this house has a gas fired furnace and traditional gas tank water heat? Source Jack Cowan 2006 utility data Annual Gas Consumption 0 20 40 60 80 100 120 140 160 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Therms
  11. 11. Compare Solar to other Technologies • Tank systems, gas and electric • Heat pump water heaters • Tankless systems, gas and electric
  12. 12. Tank Water Heaters GE 50 gal Marathon 85 gal traditional plastic lined
  13. 13. Tank Systems • Inexpensive to install • Stand by heat losses are biggest drawback...this is what we need to avoid • Most common in the US, but very uncommon in most of the world
  14. 14. Heat Pump water heaters Rheem GE Bosch
  15. 15. Heat Pump Water Heaters • More expensive to install than tank system • Very efficient in certain applications, i.e., basement located system in the south • Pulls heat from surrounding air to provide up to 50% reduction in energy usage compared to electric resistance heaters
  16. 16. Tankless
  17. 17. Tankless (Demand) Systems • More expensive to install than tank system • Eliminates standing tank heat losses • Only operates when hot water is running • Can be electric, but more commonly gas • Never runs out of hot water • May have to coordinate use when using multiple showers, laundry, etc.
  18. 18. Evaluate Costs (good generic reference, but location and conditions unknown)
  19. 19. Jeff and Karen Cowan’s Zero Energy Home, Atwood, TN
  20. 20. Solar installation ZEH • HTP stainless steel 80 gal primary tank • 4’x10’ flat plate collector • Kyocera 20w PV module for power • Backup electric resistance tank • 12v pump, expansion tank, pressure gage, valves, fittings, tubing, wiring, etc. • Source: Bill Ball,
  21. 21. A bunch of happy installers!
  22. 22. Solar Collector installed
  23. 23. PV Module Powering Circulation Pump
  24. 24. Solar Thermal primary and secondary tanks
  25. 25. Summary • Go through the process to ensure you’ve made the right decision...Is Solar for you? • If you choose Solar find a professional provider to oversee the product selection and installation • Thank you. Questions?