1 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Identifying Mechanical Systems and Improving Duct Systems WEATHERIZATION INSTALLER/TECHNICIAN FUNDAMENTALS WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012

2 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Learning Objectives By attending this session, participants will be able to: Identify common mechanical systems, including combustion appliances and cooling systems. Discuss clearance to combustibles requirements for various vent pipe types. Identify various electrical, plumbing, and safety components of mechanical systems. Illustrate proper combustion vent system exhaust system installation.

3 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Learning Objectives By attending this session, participants will be able to: Explain how a home’s forced air distribution system works. Describe mobile home duct configurations. Identify and diagnose duct leakage problems. Fix leaky ducts using correct materials and techniques. Make other duct system improvements.

4 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Combustion, Distribution & Venting Return Air Main Burner Supply Air Vent Combustion Gases Dilution Air Heat Exchanger Gas Valve Combustion Air Graphic developed for the US DOE WAP Standardized Curricula

5 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Clearance to Combustibles Oil and WoodGas Single wall 18”Single Wall 6” Double Wall Super Six, Dura Vent 6” Double Wall B-Vent or B-W Vent 1” Manufactured Chimney 2” or per Manufacturer Instructions Photo Courtesy of NRCERT

6 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Unvented Space Heaters Unvented space heaters release all of their combustion byproducts into the home. In addition to carbon dioxide and water vapor, compounds of carbon monoxide, excess air, and sulfur dioxide will be present. Photos Courtesy of NRCERT

7 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Furnaces Furnaces heat air Photo courtesy of PA Weatherization Training Center Open ended duct Single wall flue for oil heat

8 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Atmospheric Furnace Furnace Test Locations #1 80+ Induced Draft Furnace Figures courtesy of Corporation for Ohio Appalachian Development (COAD) Draft CO CO & Draft

9 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS 90+ Condensing Furnace Furnace Test Locations #2 Floor Furnace Figures courtesy of COAD Draft CO CO & Draft

10 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Furnace Test Locations #3 Fuel Oil FurnaceBarometric Damper Figure courtesy of COAD Draft CO Photo courtesy of NRCERT

11 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Non-retention head burner Typically 1,725 RPM Should be replaced Retention head burner Typically 3,450 RPM 10% more efficient Source: R. Karg Oil Burner Components #1 Fuel filter Overheat shutoff fuel valve Cutaway blast tube Burner air adjustment Retention head Source: R. Karg

12 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Source: Heating with Oil, Natural Resources Canada, Oil Burner Components #2

13 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Oil Burner Components #3 Electrode springs (thousands of volts) Electrode springs (thousands of volts) Open transformer Burner fan Electrodes for burner ignition Oil line to nozzle Oil line to nozzle Inside the burner blast tube Cad cell Source: R. Karg

14 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Oil-Fired Boiler Source: Natural Resources Canada, Boilers heat water

15 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Natural Draft Boiler and Water Heater Source: R. Karg

16 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Forced Draft Boiler Forced Draft Unit This boiler has a high static pressure burner. It vents through the wall and its combustion supply air is vented directly to the burner from the outdoors. The burner has a special cover that allows the outdoor air to flow directly to the burner. Photo courtesy of R. Karg

17 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Chimney and Vent Connectors Chimney Combustion gases mixed with room air Vent Gas heating appliance Draft hood Water heater Draft diverter Dilution air Graphic developed for the US DOE WAP Standardized Curricula

18 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS A typical mobile home downflow distribution system Forced Air System Operation #1 Graphic developed for the US DOE WAP Standardized Curricula

19 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Forced Air System Operation #2 Furnace Duct Vents Return Air Graphic developed for the US DOE WAP Standardized Curricula

20 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Duct Components Fabricated Ducts Photo courtesy of PA WTC Furnace plenum Main duct run

21 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Duct Location Crosswise Floor Joist System Lengthwise Floor Joist System Images courtesy of PA WTC

22 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Problems and Opportunities Photos courtesy of PA WTC New factory installation includes duct tape Failed duct tape

23 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Visual Checks #1 Photos courtesy of PA WTC Duct registers are common leakage sites.

24 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Desperate times call for desperate measures… …when the crawl space is the warmest room of the house! Photos courtesy of PA WTC Visual Checks #2

25 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Visual Checks #3 Photos courtesy of PA WTC Large holes Branch duct leakage

26 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Visual Checks #4 No heat? No wonder! Smashed boot Photo courtesy of PA WTC Main duct Bottom of the heat exchanger

27 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS The flashlight and mirror trick Visual Checks #5 Is that a squeegee down there? Photos courtesy of the US Department of Energy

28 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Furnace Connection Duct Termination Crossover Duct Branch Duct Register Boot TRUNK DUCT Visual Checks #6 Typical Air Leakage Locations Graphic developed for the US DOE WAP Standardized Curricula

29 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Depressurize the home to 50 pascals. Pressure pan each register location. Record pressure differences. Repair ducts and retest. Pressure Pan Testing The goal is to reduce pressure pan readings at each register location to less than 1 pascal. Remember this number Photo Source: US Department of Energy

30 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Duct repair and sealing techniques Inspect ducts and boots. Repair or replace ducts and boots. Clean ducts. Seal with mastic and fiberglass mesh tape. Seal ends of trunk line. Repair and seal furnace base. Duct inspection and modification tools Repairing & Sealing Ducts #1 Photo courtesy of the US Department of Energy

31 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Inspect for blockage and loose seams. Check the flanges and inspect for damage. Repairing & Sealing Ducts #2 Photos courtesy of the US Department of Energy

32 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Make sure to clean ducts before sealing. Repairing & Sealing Ducts #3 Photo courtesy of the US Department of Energy

33 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Repairing & Sealing Ducts #4 Repair or replace the boot. Photo courtesy of the US Department of Energy

34 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Aluminum coil stock and boot fabrication Photo courtesy of PA WTC Repairing & Sealing Ducts – Materials #1 Photo courtesy of the US Department of Energy

35 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Butyl-backed tape Repairing & Sealing Ducts – Materials #2 Photo courtesy of PA WTC Image Source:

36 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Repairing & Sealing Ducts – Materials #3 Mastic sealant Photo courtesy of the US Department of Energy Image Source:

37 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Use fiberglass mesh tape to span gaps larger than ¼ inch. Latex gloves are often your mastic brush. Sealing with Mastic #1 Photos courtesy of the US Department of Energy

38 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Seal the end of the trunk line by stuffing backer material into the duct past the last register and seal with mastic. Use screws to hold carpet up until mastic dries. Sealing with Mastic #2 Photos courtesy of the US Department of Energy

39 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Seal the duct, then patch the belly board. Mechanically fasten and seal with butyl-backed aluminum tape or mastic. Repairing and Sealing Ducts #1 Photo courtesy of PA WTCPhoto courtesy of WV GOEO

40 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Repairing and Sealing Ducts #2 Re-attach disconnected ductwork Photo courtesy of PA WTC

41 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS 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. Repairing and Sealing Ducts - Review

42 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Results! Post Pressure Pan Testing Photos courtesy of the US Department of Energy

43 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Pressure Balancing the System Measure room pressure imbalances Photo courtesy of PA WTC 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.

44 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Replace damaged registers Remove obstructions Balance the system Other Duct System Improvements Photos courtesy of PA WTC

45 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Venting Systems should: Carry all combustion byproducts to outdoors. Establish draft quickly. Be properly sized with minimal restrictions. Have long durability (corrosion resistance). Protect surrounding materials from overheating. Have adequate make up air. Venting Systems

46 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Chimneys and Vents Photo courtesy of PA Weatherization Training Center From hot water tank Chimney Single wall vent From furnace

47 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Masonry chimneys Type B-vents – double wall, round Type BW-vents – double wall, oval Type L-vents – more heat, corrosion resistant Single wall metal – interior only Plastic pipe vents – low temperature condensing furnaces Vent Types Photo courtesy of NRCERT Masonry Chimney and B-Vent

48 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Vent gas temperature Heat loss from the vent Height of the venting system Capacity of the venting system Restrictions in the venting system Ambient temperature Negative pressure in the combustion appliance zone (CAZ) Factors That Affect Vent Operation See a problem here? Photo courtesy of NRCERT

49 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Chimney Specifications Masonry chimney is too short Photo Courtesy of PA Weatherization Training Center

50 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Check for: Connections, obstructions Holes Sound liner Slope of horizontal runs Extend 3’ above roof penetration Appropriate type and size for the appliance Proper diameter Chimneys and Vents #1

51 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Chimneys and Vents #2 Chimneys and vents must not be blocked and must have no holes in the chimney or vent. Missing cleanout Blocked chimney Photos Courtesy of PA Weatherization Training Center

52 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Hole in Vent ConnectorImproper Slope Chimneys and Vents #3 Hole in vent connector Photos Courtesy of PA Weatherization Training Center Improper slope

53 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS No vent connectorReduced vent connector out of compliance with code Chimneys and Vents #4 Reduced vent connector Photos Courtesy of PA Weatherization Training Center No vent connector

54 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Water Heaters Burn marks above the burner compartment are evidence of flame roll out. Spillage of flue gases or insufficient draft is often a result of an improper installation such as this. Photo courtesy of PA Weatherization Training Center Photo courtesy of NRCERT

55 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Testing Water Heaters #1 Atmospheric Hot Water Tank Test for draft above the draft diverter. Figure courtesy of COAD Test for CO on both sides of the baffle. Photo courtesy of NRCERT

56 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Test for CO directly into the breech of the unit on both sides of the baffle that runs up through the center of the tank. On start up, time the amount of spillage. Then test draft above the draft diverter. Spillage should not exceed one minute. Testing Water Heaters #2 Photos courtesy of NRCERT Draft diverter

57 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Photos courtesy of NRCERT Chimney Liner

58 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS CONDENSER AIR HANDLER Air Conditioning Units Packaged Heat Pump Central System Often mounted on roof or concrete slab outdoors Includes Room A/C units (most common in low- income homes) Air Conditioning Systems Split System Condenser outdoors A/C coil indoors, often in furnace, heat pump, or supply duct Mini-split ductless systems place the condenser outdoors, air handler indoors. * All A/C need clean filters and coils to allow good air flow and efficient heat transfer.

59 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Outdoor Cleaning frequency depends on levels of dust and pollen in area High levels: Clean annually Low levels: Every 3 years Indoor Should be protected by well-fitting clean filter Keeps blower and coils clean Easier to replace or clean filters than blowers or coils Indoor and Outdoor Coils Outdoor coils Indoor coils Adapted from image on

60 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Parts of Room A/C housing outdoor coil compressor condensate drain indoor coil controls filter removable grill Photo courtesy of Energy Out West Weatherization Field Guide. Copyright Saturn

61 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Central A/C Components The outdoor condenser and coils dissipate collected heat to the outdoor air. In dusty climates, the coils should be cleaned annually to maintain efficient performance. Adapted from image on

62 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Photo courtesy of The U.S. Department of Energy Covering the unit during periods of disuse prevents clogging with leaves and other debris.

63 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – July 2012eere.energy.gov IDENTIFYING MECHANICAL SYSTEMS & IMPROVING DUCT SYSTEMS Furnaces heat air and use ducted distribution systems. Boilers heat water and transport heat through the living space through pipes connected to radiators. Cooling systems can be packaged or split systems. If the condenser and coils are in separate locations, it is a split system. Most ducts are very prone to leakage. Diagnosing and repairing duct leakage is the single, most cost- effective measure you can apply to many 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. Summary