WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 1 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010
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Learning Objectives DUCT DIAGNOSTICS AND REPAIR
By attending this session, participants will become aware of: • How a mobile home’s home s forced air distribution system works • Mobile home duct configurations • Duct leakage problems and how to diagnose them • Materials and techniques to fix leaky ducts • How to modify a belly return system • Other duct system y improvements p
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August 2010
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Forced Air System Operation #1 DUCT DIAGNOSTICS AND REPAIR
A typical mobile home downflow distribution system 3 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010
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Forced Air System Operation #2 DUCT DIAGNOSTICS AND REPAIR
Return Air
Furnace
Vents
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Duct
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Duct Components DUCT DIAGNOSTICS AND REPAIR
Furnace plenum
Main duct run
Photo courtesy of PA WTC
Fabricated Ducts 5 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010
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Duct Location DUCT DIAGNOSTICS AND REPAIR
Lengthwise Floor Joist System
Crosswise Floor Joist System 6 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010
August 2010
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Problems and Opportunities DUCT DIAGNOSTICS AND REPAIR
New factory installation includes duct tape
Failed duct tape Photos courtesy of PA WTC
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Visual Checks #1 DUCT DIAGNOSTICS AND REPAIR
Duct registers are common leakage sites
Photos courtesy of PA WTC
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Visual Checks #2 DUCT DIAGNOSTICS AND REPAIR
Photos courtesy of PA WTC
…when the crawl space is the warmest room of the house!
Desperate times call for desperate measures…
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Visual Checks #3 DUCT DIAGNOSTICS AND REPAIR
Branch duct leakage Large holes
Photos courtesy of PA WTC
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Visual Checks #4 DUCT DIAGNOSTICS AND REPAIR
Bottom of the heat exchanger Smashed boot
Main duct Photo courtesy of PA WTC
No heat? No wonder! 11 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010
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Visual Checks #5 DUCT DIAGNOSTICS AND REPAIR
Photos courtesy of the US Department of Energy
The old flashlight and mirror trick
Is that a squeegee down there?!
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Visual Checks #6 DUCT DIAGNOSTICS AND REPAIR
Typical Air Leakage Locations Register Boot Furnace Connection
Branch Duct
Duct Termination
Crossover Duct
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Pressure Pan Testing DUCT DIAGNOSTICS AND REPAIR
Remember this number!
• Depressurize the home to 50 pascals • Record pressure pan reading at each register location • Repair ducts and retest
The goal is to reduce pressure pan readings at each register location to less than 1 pascal. Photo Source: US Department of Energy 14 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010
August 2010
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Repairing & Sealing Ducts #1 DUCT DIAGNOSTICS AND REPAIR
Duct repair and sealing techniques • Inspect ducts and boots • Repair or replace ducts and boots • Clean ducts • Seal with mastic and mesh tape • Seal ends of trunk line • Repair and seal furnace base
Photo courtesy of the US Department of Energy
DUCT INSPECTION AND MODIFICATION TOOLS 15 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010
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Repairing & Sealing Ducts #2 DUCT DIAGNOSTICS AND REPAIR
Photos courtesy of the US Department of Energy
Inspect for blockage and loose seams
Check the flanges and inspect for damage
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Repairing & Sealing Ducts #3 DUCT DIAGNOSTICS AND REPAIR
Make sure to clean ducts before sealing
Photo courtesy of the US Department of Energy
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Repairing & Sealing Ducts #4 DUCT DIAGNOSTICS AND REPAIR
Repair or replace the boot
Photo courtesy of the US Department of Energy
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Mastic sealant Photo courtesy of the US Department of Energy
Image Source: http://www.rcdmastics.com/pd6.asp
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Sealing with Mastic #1 DUCT DIAGNOSTICS AND REPAIR
Photos courtesy of the US Department of Energy
Use mesh tape to span gaps larger than ¼ inch
Latex gloves are often your mastic brush
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Sealing with Mastic #2 DUCT DIAGNOSTICS AND REPAIR
Photos courtesy of the US Department of Energy
Seal the end of the trunk line by stuffing backer material such as coarse furnace filter scraps into the duct past the last register and seal with mastic
Use screws to hold carpet up until mastic dries
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Repairing and Sealing Ducts #1 DUCT DIAGNOSTICS AND REPAIR
Photo courtesy off WV GOEO GO O
Seal the duct, then patch the belly board
Photo courtesy off PA WTC C
Mechanically fasten and seal with mastic and mesh tape
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Repairing and Sealing Ducts #2 DUCT DIAGNOSTICS AND REPAIR
Photo courtesy of PA WTC
Re-attach disconnected ductwork 24 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010
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Repairing and Sealing Ducts - Review DUCT DIAGNOSTICS AND REPAIR
Concentrate on the following locations: – – – –
Risers Ends Branch ducts Furnace plenum
• You may need to cut the rodent barrier to access some leaks • Never N use d ductt ttape • Mechanically fasten components where necessary
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Post Pressure Pan Testing DUCT DIAGNOSTICS AND REPAIR
Photos courtesy of the US Department of Energy
Results! 26 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010
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Belly Return System Conversion #1 DUCT DIAGNOSTICS AND REPAIR
• Permanently seal all return registers (i l di th (including the regist i ter in the floor of the furnace closet) • Create a hallway return system • Add a louver to the f furnace closet l t door • Undercut doors to adjacent rooms or provide louvers • Verify good air flow with a pressure balancing test
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Belly Return System Conversion #2 DUCT DIAGNOSTICS AND REPAIR
Seal belly return registers in the furnace closet
Photos courtesy of PA WTC
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Belly Return System Conversion #3 DUCT DIAGNOSTICS AND REPAIR
Photos courtesy of PA WTC
Return may extend behind the furnace cabinet and must be sealed
Aluminum coil stock was fastened to the floor with hex-head screws
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Belly Return System Conversion #4 DUCT DIAGNOSTICS AND REPAIR
Photos courtesy of PA WTC
Permanently seal all return registers 30 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010
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Belly Return System Conversion #5 DUCT DIAGNOSTICS AND REPAIR
Leave 2 square inches of q free vent area per 1,000 BTUs of furnace input
Photo courtesy of PA WTC
Install a return louver in the furnace closet door 31 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010
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Pressure Balancing the System DUCT DIAGNOSTICS AND REPAIR
Measure room pressure imbalances i b l • Room pressure imbalances over 4 pascals should be remedied by adding supply or return air, then retesting • Make sure that doors to interior rooms are sufficiently undercut to allow air to return to the furnace
Photo courtesy of PA WTC
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Other Duct System Improvements DUCT DIAGNOSTICS AND REPAIR
• Replace damaged registers • Remove obstructions • Balance the system: – Install baffles to enhance airflow to distant rooms – Shorten the end of duct runs beyond the last register – Enhance airflow by removing obstructions, replacing damaged registers, and shortening unneeded duct runs Photos courtesy of PA WTC
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Summary DUCT DIAGNOSTICS AND REPAIR
• Mobile home ducts are very prone to leakage. • Diagnosing and repairing duct leakage is the single most cost-effective measure you can apply to mobile homes. • Effective duct sealing is possible through the use of innovative duct sealing materials. provement measures, such as cleaning, g • Other duct imp removing obstructions, and system balancing can improve comfort and lower fuel bills.
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