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Residential Ducts

Residential Ducts. Bruce Wilcox, BSG John Proctor, PEG Ken Nittler, Enercomp. Changes for Duct Systems. Increase prescriptive duct insulation from R-4 to R-8 in climate zones 1 through 5 and 9 through 16 Improved treatment of air conditioning air flow and fan energy:

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Residential Ducts

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  1. Residential Ducts • Bruce Wilcox, BSG • John Proctor, PEG • Ken Nittler, Enercomp

  2. Changes for Duct Systems • Increase prescriptive duct insulation from R-4 to R-8 in climate zones 1 through 5 and 9 through 16 • Improved treatment of air conditioning air flow and fan energy: • fan flow measured using 3 methods • optional credit for measured fan Watts • focus TXV credit on charge only • Prohibit porous inner core flex duct

  3. Prescriptive Duct Insulation • Currently R-4.2 • Proposed • R-8 in climate Climate Zones 1 through 5 and 9 through 16 • remains at R-4.2 in Climate Zones 6, 7 and 8 • Based on lowest life cycle cost

  4. Cost of Duct Insulation

  5. Life Cycle Energy Cost Savings R-4.2 to R-8 for Crawl Ducts

  6. Revised Measurement Techniques • To field verify adequate air flow • Flow Capture Hood (current) • Plenum Pressure Matching (current) • Flow Grid (new) • New product • Slides into air handler filter slot • Fast and Accurate • To field verify fan Watts (new) • Portable Watt meter • Utility Revenue Meter

  7. Air Flow Measures

  8. Indoor Air Handler Fan Energy • Current: • not accounted for in performance compliance • defaulted, not realistically tested in ratings • New: • Standard Design set to field measured average • 0.51 W/cfm • 0.25 CFM/Btu rated capacity (300 cfm/ton) • Proposed defaults to Standard Design • optional significant credit for verified reduced Watts with adequate air flow

  9. TXV and Air Flow • Current: • TXV assumed to partly compensate for low air flow • New: • PG&E tests show no effect • TXV effect on air flow removed

  10. PG&E Test Results

  11. Proposed AC Efficiency Factors

  12. Current AC Efficiency Factors

  13. Comparison of Air Conditioning Energy Savings

  14. Porous inner core flex duct • Outer plastic is only air barrier • Any damage becomes a leak • Prohibited in Florida Energy Code • “Flexible ducts having porous inner cores shall not be used.” • Same language proposed

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