Residential Ducts

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
• PGE tests show no effect
• TXV effect on air flow removed

10
PGE 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