To save energy seal ducts. New code requirements will test ducts for air leakage. Find out the best way to seal your HVAC system whether it's a retrofit or a new system.

1. Quality HVAC System
Installation
The goal for a Heating, Ventilation and Air
Conditioning (HVAC) system is to provide proper air
flow, heating, and cooling to each room

2. Class Sponsors
Nevada Housing Division
Nevada State Office of Energy

3. Instructor
Barbara Collins
Energy Rated Homes
 Building Science Consultant
 Certified Green Building
Verifier
 Certified HERS Rater
 Energy Star Homes Partner

4. Class Objectives
 Understand IECC Duct Sealing and Testing
Requirements
 Learn How to Meet IECC and Energy Star
Homes Requirements
 Learn How to Avoid Common Installation
Problems
 Learn About IECC Requirement for Manual J
Load Calculation
 Learn About Proposed Retrofit Programs and
Rebates For Growing Your Business

5. HVAC System
 Poor design and installation increases energy
costs 10 –30%
 Sizing
 Design
 Installation

6. Ducts - IECC
 Insulation (Prescriptive)
 Ducts outside the building
envelope: R-8
 All other ducts: R-6
 Sealing (Mandatory)
 Joints and seams shall comply with IRC,
Section M1601.4.1
 Building framing cavities shall not be used as
supply ducts

7. Duct Tightness Tests
 All ducts, air handlers, filter boxes and building
cavities used as ducts shall be sealed (Section
403.2.2)
 Duct tightness shall be verified by testing
 Only Exception: Duct tightness test is not
required if the air handler and all ducts are
located within conditioned space
Mandatory Requirements

8. Current Code Requirements
 Must comply with all aspects of UL181
standards
 Fittings, joints & seams of duct system shall
be made substantially air tight by means of
tapes, mastics, gasketing or other means.

9. SEAL DUCTS,
SAVE ENERGY
Sealing ducts is a cost-effective
energy efficiency practice that gives
a high return on investment

10. Home Energy Use
 Residential energy use 22% of U.S. total
 25% of carbon emissions in U.S.
 Heating & cooling is 40 – 60 % of home
energy use

11. Why seal ducts
 Leaks waste energy and money
 Average system leakage
 New construction 20%
 Existing homes 30%
 Duct sealing reduces heating and cooling
energy losses and saves money

12. Other Problems
 Duct leakage reduces air flow, conditioned air
isn’t delivered to rooms which can cause wide
temperature swings between rooms
 IAQ issues with return leaks drawing in air
from attics, garages, crawlspaces
 Pressure differentials can cause excess
building air leakage and backdrafting

13. Duct Tightness Tests
 Post construction tests
 Option 1
 Leakage to outdoors: ≤8 cfm/per 100 ft2
of
conditioned floor area
 OR
 Option 2
 Total leakage: ≤12 cfm/per 100 ft2
of
conditioned floor area
Mandatory Requirements

14. Duct Tightness Tests
Rough-in test Options
 Option 1
 Total leakage ≤6 cfm/per 100 ft2
of conditioned
floor area
OR
 Option 2
If air handler not installed at time of test total air
leakage ≤4 cfm/per 100 ft2
Mandatory Requirements

15. Exceptions: Duct tightness test is not required if
the air handler and all ducts are located within
conditioned space

16. Ventilation
Outdoor air intakes and exhausts shall have
automatic or gravity dampers that close when
the ventilation system is not operating
Mandatory Requirements

17. Tested at a pressure differential of 0.1 in
w.g. (25Pa) across entire system,
including manufacturer’s air handler
enclosure

24. Mastic Sealant
Non-toxic – Low VOC
Green credits
Dries to touch in about ½
hour
Recommended Set time
= 20 hours

25. More on Mastic
 High strength adhesive compound
 Usually applied by trowel, brush, caulking gun
or hand
 3 types- water-based; solvent-based; and
two-component curing systems
 Water-based is the safest and easiest to use
It performs as well and in some cases better
than the other 2

26. VOCs in mastics
 Volatile organic compounds
 In water-based mastics, the only volatile
compound is water which is inorganic
 VOCs are infinitesimally small (not
recordable)
 Water-based mastics pose a low health risk
compared to solvent-based and two-
component mastics
 Safer for the user, better IAQ, greener

27. How to apply mastic
 Step 1 - Clean Duct Surface
 Wipe dust oil and grease from the duct surface
 Step 2 - Apply the mastic
 Gaps less than 1/4″, load brush with mastic
and coat entire joint with a continuous strip
 Use brush end to work mastic into joint
 Spread mastic at least one inch on each side
of the joint.
 The mastic should be thick enough to hide the
metal surface of the duct.

28. Mesh for Gaps
 If gap is larger than 1/4
inch use fiberglass
mesh too
 If mesh is sticky on
one side, cut enough
to cover joint, press in
place, then completely
cover it with mastic.
 If mesh does not have
a sticky side, apply a
thin layer of mastic,
press mesh into the
mastic, then apply a
finish layer of mastic.

30. Tools & Materials
Head lamp, hat with light, or flashlight
A work board to span joists in attics
Gallon pail and 2-3 caulk tubes of mastic
Caulk Gun, mastic brush, fin and plenum brush
Roll of mesh
2-3 pairs of latex gloves
2-3 cloths, can of coil and fin cleaner to wipe joints
clean before applying mastic and clean up
Utility knife and telescoping mirror
Pliers, screw driver and tin snips
For Sealing Existing Systems

31. Sealing Priorities
1. Disconnected components
2. Connections between the air handling unit
and the plenums
3. All seams in the air handling units and
plenums, takeoffs, boots, and other
connections, especially site-built items.

32.  Remove tie holding duct
to connection
 Roll back insulation and
outer cover
 Seal inner core with
mastic and band
 Roll insulation down
and vapor barrier/outer
cover
 Put band and seal with
mastic

33.  Wrap Ducts with insulation
 Insulation may be installed over wet mastic
but do not move the ducts too much or mastic
seal could be damaged.
 All duct support work should be done before
applying mastic
 Wait 2 -4 hours and water based mastic will
be dry to the touch

34. AIRTIGHT DUCT SYSTEM
Boots and Cans
 Seal seams with
mastic
Thin mastic will crack
Make seal permanent
Plug Don’t Paint
Thick as a Nickel = .077 in
1/16 inch = .0625 in

37. AIRTIGHT DUCT SYSTEM
Flexible Ducts
Seal inner sleeve & outer
sleeve
 Plastic strap holds the
inner liner firmly to the
duct or fitting.
 Mastic seals liner to
connection and covers the
end of the liner
 Use drawband to hold
outer sleeve (vapor
barrier)
Vapor barrier should be complete.
All holes, rips, and seams must be
sealed with mastic or approved tape

39. AIRTIGHT DUCT SYSTEM
Metal Ducts and Plenums, Duct Board
Boxes
 Openings greater than 1/4 inch should be
sealed with mastic and mesh
 Openings less than 1/4 inch should be
sealed with mastic
 Special attention to collar connections to
duct-board and/or sheet metal; seal around
the connection with mastic

40. Ts Ys & Ls
 Use mesh tape to
strengthen the joint
where ducts of different
shapes meet.
 Seal all seams, even
manufactured ones.

47. Sealant applied, still leaks

48. FABRICATION & INSTALLATION
GUIDELINES
 The air handler box should be air-tight

49. Air Handler Leaks

51. Mechanical Systems & Equipment

52. AHUs & Plenums
 Fill all openings for
wiring, plumbing and
refrigerant lines.
 Seal all seams in the air
handler and plenums.
 Tape around access
panels, so they can be
opened for service.

56. AIRTIGHT HVAC SYSTEM
Air handlers on platforms
 May be located in a closet indoors
 Framers must be told not to put plywood top
on before walls are sheetrocked (or duct
board) to underside of platform floor
 All wall surfaces must be sheetrocked next to
and in platform
 Seal all joints

62. Boots
 Seal all joints, including
manufactured seams.
 The transition between
the duct and boot may
require mesh tape.

64. AIRTIGHT DUCT SYSTEM
All Duct Types
Register boxes should be sealed to the drywall or floor
with caulking or mastic

65. AIRTIGHT DUCT SYSTEM
All Duct Types
Register boxes should be sealed to the drywall or floor
with caulking or mastic

73. SHEET MEATAL CONNECTIONS
 Start the inner fitting into the outer fitting
 Apply a 2” wide band of mastic 20 – 30 mils thick to
the exposed part of the inner fitting
 Fully seat the joint and mechanically fasten with
sheet metal screws or rivets
 Apply a 2.5” wide band of mastic 20 – 30 mils thick to
the outside of the joint covering the screws or rivets
and joint gap
 Allow at least 12 hours drying time before starting
system
 Temperature and humidity conditions can vary,
longer dry times may be required

74. Locating ducts within conditioned
space
 Within conditioned space means within
insulated space and within the air barrier
boundary.
 Attics and crawlspaces are not conditioned
space
 Critical that space is truly indoors and sealed
from unconditioned areas
 Multi-level dwellings more easily
accommodate ducts in conditioned space

77. Ducts in Unconditioned Space
 Usually ducts are located in attics and
crawlspaces
 Conduction losses are amplified by big
temperature differences
 Convection losses by leakage
Long duct runs in attics lose 15%+ of cooling
capacity before end

78. Benefits of locating ducts in
conditioned space
 Ducts can be smaller
 May have shorter runs reduce pressure drop
and improve efficiency
 Can reduce HVAC system costs by reducing
loads
 Reduce conduction losses
 Improve comfort
 No Testing in 09 IECC

79. EXISTING HOMES
 In existing homes, not unusual to find
disconnected duct components, takeoffs
loose from ducts or ducts disconnected from
register boots

80. EXISTING HOMES
 Leaks connected to the outdoors are more
important than leaks inside home’s thermal
envelope
 Holes near the air handler are more important
than distant holes with relatively low
pressures
 Supply system leaks waste more energy than
return system leaks
 Furnaces

81. Equipment Sizing
 Load calculations determine the
proper capacity (size) of equipment
 Goal is big enough to ensure
comfort but no bigger
 Calculations with ACCA Manual J
protocol or other approved methods
Mandatory Requirements

82. Oversizing
What do you get when you combine cognitive
bias with inaccurate information?

83. Oversizing
 Old Rules of Thumb
 One Size Fits All
 US Department of Energy
 Most systems are oversized, increasing
installation cost for every house

84. Oversizing
 Sizing example
House with standard metal windows w/ .75 U-
Value and .88 SHGC and 20% duct leakage
 Calculated Sensible cooling load = 58880 Btu

85. Oversizing
 Sizing example
 Same house with Low-E windows and tight
duct system @ 5% leakage
 Sensible cooling load = 43877 Btu
 Average of 1-2” decrease in duct diameter
sizes

86. Oversizing
 Installation cost is higher
 Operating cost over life of equipment is
higher
 Can cause comfort problems
 Improvements in building envelope should
reduce loads

87. Right Sizing
 Costs less to install – saves builder money
 Costs less to operate - not starting and
stopping all the time
 Short cycling can cause bigger swings in
supply air, less comfort
 Better humidity control

88. DESIGN HVAC SYSTEM
Loads and CFM Calculation
 ACCA Manual J Load Calculation or
equivalent required
 Calculate heat loss and heat gain for each
room
Total room loads to determine system
requirements.

89. Manual J –Load Calc
 The local climate – ASHRAE 30 year average
 Size, shape, and orientation of the house
 Insulation levels
 Window area, location, and type
 Air infiltration rates
 Number of occupants
 Types and efficiencies of lights and major home
appliances (which give off heat)
 ACCA - Air Conditioning Contractors of America
www.acca.org

90. A Quality HVAC System
 Be properly sized to provide correct air flow, and
meet room-by-room calculated heating and cooling
loads.
 Have sealed ductwork that will provide proper air
flow.
 Be installed with a return system designed to provide
correct return air flow.
 Have balanced air flows between supply and return
systems to maintain neutral pressure in the home.
 Be properly charged with refrigerant

91. “It’s tough to make
predictions,
especially about
the future.”
- Yogi Berra

92. U.S. Dept of Energy
30/30 Vision
2012 IECC 30% More Stringent 2006 IECC
More verification testing

93. Ductwork
 Single most important energy measure for
most homes- low hanging fruit
 Locating inside conditioned space is optimal
 Seal joints with mastic not duct tape

94. Equipment Size
 Oversizing is common and expensive –
upfront and during life
 Sizing properly can reduce cost and help pay
for increased cost of other efficiency features

97. HOME STAR Program
 $6 Billion Residential Retrofit
 SILVER STAR
– $3.6 Billion
 GOLD STAR
- $1.8 Billion
 Financing / QA / Admin
– $600 Million

98. Recovery Through Retrofit
 Construction
24.7% unemployment in construction industry
38% drop in employment since 2006
 Manufacturing
24.5 % drop in construction related manufacturing
Construction-related manufacturing at less than
62% of capacity
 Construction Retail
14% drop in employment since 2006

99. SILVER STAR
 Up to a $1,500 rebate per measure
 Not to exceed $3,000
 Not to exceed 50% of project cost
 Rebate delivered to customer at time of
purchase, but paid to installer
 All retrofits must be installed by a certified
contractor

100. SILVER STAR
 Eligible Measures
 Air Sealing Duct Seal / Replacement
 Heating & Cooling Equipment
 Attic Insulation
 Wall Insulation
 Domestic Hot Water
 Floor Insulation
 Windows and Doors

101.  $3,000 incentive for a 20% savings based
on assessment by building performance
professional
 • $1,000 for each additional 5% savings
 • Not to exceed 50% of project cost or
$8,000

102. HOME STAR Financing
 Creates up to $1.5 Billion in low interest consumer
financing
 Allows American families to achieve cash flow
positive results on most HOME STAR projects from
day one

103. Learn from the mistakes of others.
You can't possibly live long enough
to make them all yourself
--Sam Levinson

104. Thank you for participating
 Any questions
 Please complete your evaluation sheets so
we can plan future events