MOBILE HOME TRAINING Duct Diagnostics and Repair WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 1 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov Learning Objectives By attending this session, participants will become aware of: How a mobile 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 improvements 2 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 1
Forced Air System Operation #1 A typical mobile home downflow distribution system 3 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov Forced Air System Operation #2 Return Air Furnace Vents Duct 4 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 2
Duct Components Furnace plenum Main duct run Photo courtesy of PA WTC Fabricated Ducts 5 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov Duct Location Lengthwise Floor Joist System Crosswise Floor Joist System 6 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 3
Problems and Opportunities New factory installation includes duct tape Failed duct tape Photos courtesy of PA WTC 7 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov Visual Checks #1 Duct registers are common leakage sites Photos courtesy of PA WTC 8 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 4
Visual Checks #2 Photos courtesy of PA WTC when the crawl space is the warmest room of the house! Desperate times call for desperate measures 9 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov Visual Checks #3 Branch duct leakage Large holes Photos courtesy of PA WTC 10 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 5
Visual Checks #4 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 eere.energy.gov Visual Checks #5 Photos courtesy of the US Department of Energy The old flashlight and mirror trick Is that a squeegee down there?! 12 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 6
Visual Checks #6 Typical Air Leakage Locations Duct Termination Furnace Connection Register Boot Branch Duct Crossover Duct 13 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov Pressure Pan Testing 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 eere.energy.gov August 2010 7
Repairing & Sealing Ducts #1 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 eere.energy.gov Repairing & Sealing Ducts #2 Photos courtesy of the US Department of Energy Inspect for blockage and loose seams Check the flanges and inspect for damage 16 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 8
Repairing & Sealing Ducts #3 Make sure to clean ducts before sealing Photo courtesy of the US Department of Energy 17 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov Repairing & Sealing Ducts #4 Repair or replace the boot Photo courtesy of the US Department of Energy 18 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 9
Repairing & Sealing Ducts Materials #1 Photo courtesy of the US Department of Energy Photo courtesy of PA WTC Aluminum coil stock and boot fabrication 19 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov Repairing & Sealing Ducts Materials #3 Mastic sealant Photo courtesy of the US Department of Energy Image Source: http://www.rcdmastics.com/pd6.asp 20 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 10
Sealing with Mastic #1 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 21 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov Sealing with Mastic #2 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 22 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 11
Repairing and Sealing Ducts #1 Photo courtesy of WV GOEO O Photo courtesy of PA WTC Seal the duct, then patch the belly board Mechanically fasten and seal with mastic and mesh tape 23 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov Repairing and Sealing Ducts #2 Photo courtesy of PA WTC Re-attach disconnected ductwork 24 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 12
Repairing and Sealing Ducts - Review Concentrate on the following locations: Risers Ends Branch ducts Furnace plenum You may need to cut the rodent barrier to access some leaks Never use duct tape Mechanically fasten components where necessary 25 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov Post Pressure Pan Testing Photos courtesy of the US Department of Energy Results! 26 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 13
Belly Return System Conversion #1 Permanently seal all return registers (including the regist er in the floor of the furnace closet) Create a hallway return system Add a louver to the furnace closet door Undercut doors to adjacent rooms or provide louvers Verify good air flow with a pressure balancing test 27 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov Belly Return System Conversion #2 Seal belly return registers in the furnace closet Photos courtesy of PA WTC 28 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 14
Belly Return System Conversion #3 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 29 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov Belly Return System Conversion #4 Photos courtesy of PA WTC Permanently seal all return registers 30 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 15
Belly Return System Conversion #5 Leave 2 square inches of 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 eere.energy.gov Pressure Balancing the System Measure room pressure imbalances 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 32 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 16
Other Duct System Improvements 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 33 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov Summary 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. Other duct improvement measures, such as cleaning, removing obstructions, and system balancing can improve comfort and lower fuel bills. 34 WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM August 2010 eere.energy.gov August 2010 17