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MOBILE HOME TRAINING

Duct Diagnostics and Repair

1 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.govWEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010

Learning Objectives

By attending this session, participants will become aware of:• How a mobile home’s forced air distribution system works

DUCT DIAGNOSTICS AND REPAIR

• 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

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Forced Air System Operation #1DUCT DIAGNOSTICS AND REPAIR

A typical mobile home downflow distribution system

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Forced Air System Operation #2DUCT DIAGNOSTICS AND REPAIR

Furnace DuctVents

Return Air

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Duct Components

Furnace plenumFurnace plenum

DUCT DIAGNOSTICS AND REPAIR

Main duct runMain duct run

5 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Photo courtesy of PA WTC

Fabricated Ducts

Duct LocationDUCT DIAGNOSTICS AND REPAIR

Lengthwise Floor Joist System

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Crosswise Floor Joist System

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Problems and OpportunitiesDUCT DIAGNOSTICS AND REPAIR

New factory installation includes duct tape

New factory installation includes duct tape

Failed duct tapeFailed duct tape

7 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Photos courtesy of PA WTC

Failed duct tapeFailed duct tape

Visual Checks #1DUCT DIAGNOSTICS AND REPAIR

Duct registers are common leakage sites

8 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Photos courtesy of PA WTC

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Visual Checks #2DUCT DIAGNOSTICS AND REPAIR

9 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Desperate times call for desperate measures…

Photos courtesy of PA WTC

…when the crawl space is the warmest room of the house!

Visual Checks #3DUCT DIAGNOSTICS AND REPAIR

Large holesLarge holes

Branch duct leakageBranch duct leakage

10 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Photos courtesy of PA WTC

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Visual Checks #4

Bottom of the heat exchangerBottom of the

heat exchanger

DUCT DIAGNOSTICS AND REPAIR

Smashed bootSmashed boot

11 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Photo courtesy of PA WTC

No heat? No wonder!

Main ductMain duct

Visual Checks #5DUCT DIAGNOSTICS AND REPAIR

12 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

The old flashlight and mirror trick

Photos courtesy of the US Department of Energy

Is that a squeegee down there?!

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Visual Checks #6DUCT DIAGNOSTICS AND REPAIR

Typical Air Leakage Locations

Furnace Connection

DuctTermination

Branch Duct

Register Boot

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Crossover Duct

Pressure Pan Testing

• Depressurize the home to 50 pascals

Remember this number!

DUCT DIAGNOSTICS AND REPAIR

• Record pressure pan reading at each register location

• Repair ducts and retest

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The goal is to reduce pressure pan readings at each register location to less than 1 pascal.

Photo Source: US Department of Energy

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Duct repair and sealing techniques

• Inspect ducts and boots

Repairing & Sealing Ducts #1DUCT DIAGNOSTICS AND REPAIR

• Inspect ducts and boots

• Repair or replace ducts and boots

• Clean ducts

• Seal with mastic and mesh tape

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• Seal ends of trunk line

• Repair and seal furnace base

DUCT INSPECTION AND MODIFICATION TOOLS

Photo courtesy of the US Department of Energy

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Repairing & Sealing Ducts #2DUCT DIAGNOSTICS AND REPAIR

Inspect for blockage and loose seams

Photos courtesy of the US Department of Energy

Check the flanges and inspect for damage

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Repairing & Sealing Ducts #3DUCT DIAGNOSTICS AND REPAIR

Make sure to clean ducts before sealing

17 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Photo courtesy of the US Department of Energy

Repairing & Sealing Ducts #4

Repair or replace the bootRepair or replace the boot

DUCT DIAGNOSTICS AND REPAIR

18 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Photo courtesy of the US Department of Energy

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Repairing & Sealing Ducts – Materials #1

DUCT DIAGNOSTICS AND REPAIR

19 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Photo courtesy of the US Department of Energy Photo courtesy of PA WTC

Aluminum coil stock and boot fabrication

Repairing & Sealing Ducts – Materials #3

DUCT DIAGNOSTICS AND REPAIR

20 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

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 #1DUCT DIAGNOSTICS AND REPAIR

21 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Use mesh tape to span gaps larger than ¼ inch

Photos courtesy of the US Department of Energy

Latex gloves are often your mastic brush

Sealing with Mastic #2DUCT DIAGNOSTICS AND REPAIR

22 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

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

Photos courtesy of the US Department of Energy

Use screws to hold carpet up until mastic dries

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Repairing and Sealing Ducts #1DUCT DIAGNOSTICS AND REPAIR

f Cf GO O

23 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Seal the duct, Mechanically fasten and seal then patch the belly board with mastic and mesh tape

Photo courtesy of PA WTCPhoto courtesy of WV GOEO

Repairing and Sealing Ducts #2DUCT DIAGNOSTICS AND REPAIR

24 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Photo courtesy of PA WTC

Re-attach disconnected ductwork

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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

N d t t

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• Never use duct tape

• Mechanically fasten components where necessary

Post Pressure Pan TestingDUCT DIAGNOSTICS AND REPAIR

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Results!

Photos courtesy of the US Department of Energy

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(i l di th i t

DUCT DIAGNOSTICS AND REPAIR

(including the regist

f l t d

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furnace closet d

Belly Return System Conversion #2

Seal belly return registers in the furnace closetSeal belly return registers in the furnace closet

DUCT DIAGNOSTICS AND REPAIR

28 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Photos courtesy of PA WTC

Belly Return System Conversion #1

• Permanently seal all return registers

er in the floor of the furnace closet)

• Create a hallway return system

• Add a louver to the oor

• 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 #3DUCT DIAGNOSTICS AND REPAIR

29 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Photos courtesy of PA WTC

Return may extend behind Aluminum coil stock was the furnace cabinet and fastened to the floor with

must be sealed hex-head screws

Belly Return System Conversion #4DUCT DIAGNOSTICS AND REPAIR

30 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Photos courtesy of PA WTC

Permanently seal all return registers

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Belly Return System Conversion #5

Leave 2 square inches of Leave 2 square inches of

DUCT DIAGNOSTICS AND REPAIR

qfree vent area per 1,000 BTUs of furnace input

qfree vent area per 1,000 BTUs of furnace input

31 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010 eere.energy.gov

Photo courtesy of PA WTC

Install a return louver in the furnace closet door

Pressure Balancing the System

Measure room i b l

DUCT DIAGNOSTICS AND REPAIR

pressure imbalances

• Room pressure imbalances over 4 pascals should be remedied by adding supply or return air, then retesting

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• 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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•• Remove obstructions

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–

Photos courtesy of PA WTC

provement measures, such as cleaning,

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Other Duct System ImprovementsDUCT 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 registerEnhance airflow by removing obstructions, replacing damaged registers, and shortening unneeded duct runs

SummaryDUCT 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.

• Other duct imremoving obstructions, and system balancing can improve comfort and lower fuel bills.