HVAC Install  - Trust But Verify
Upcoming SlideShare
Loading in...5
×
 

HVAC Install - Trust But Verify

on

  • 1,927 views

2009 IECC, Air Leakage Testing Requirements, How to seal an existing leaky duct system,

2009 IECC, Air Leakage Testing Requirements, How to seal an existing leaky duct system,
HVAC System Sizing

Statistics

Views

Total Views
1,927
Views on SlideShare
1,927
Embed Views
0

Actions

Likes
2
Downloads
169
Comments
0

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment
  • No Trade offs allowed for duct insulation. Exception: - ducts completely inside the building envelope Building framing cavities shall not be used as supply ducts.
  • Equipment sizing is a direct reference to the IRC. Oversized equipment has a higher initial cost, a higher operating cost, provides less comfort, and the short-cycling reduces the equipment life expectancy. Any one of these is a good reason not to oversize. Heating and cooling system design loads for the purpose of sizing systems and equipment shall be determined in accordance with the procedures described in the ACCA Manual J or an equivalent computation procedure.
  • Equipment sizing is a direct reference to the IRC. Oversized equipment has a higher initial cost, a higher operating cost, provides less comfort, and the short-cycling reduces the equipment life expectancy. Any one of these is a good reason not to oversize. Heating and cooling system design loads for the purpose of sizing systems and equipment shall be determined in accordance with the procedures described in the ACCA Manual J or an equivalent computation procedure.

HVAC Install  - Trust But Verify HVAC Install - Trust But Verify Presentation Transcript

  • Quality HVAC System Installation Trust But Verify
  • 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
  • Instructor
    • Barbara Collins
    • ERH West
    • Building Performance Consultant
    • Certified NAHB Green Building Verifier
    • Certified RESNET HERS Rater
    • Energy Star Homes Partner
    • Certified Environments for Living Verifier
  • Class Objectives
    • Understand HVAC system air leakage testing requirements in the 2009 IECC
    • Recognize the benefits of sealing ducts for savings, system performance and indoor air quality
    • Understand how ducts are tested for leakage
    • Identify resources for local building departments
    • Identify the best techniques to seal duct systems; what inspectors should see on inspections
    • Understand the IECC requirements for sizing of HVAC equipment
  • 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.
  • 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
  • 2009 IECC 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
    • SEAL DUCTS,
    • SAVE ENERGY
    • Sealing ducts is a cost-effective energy efficiency practice that gives a high return on investment
  • HVAC System
    • Poor design and installation increases energy costs 10 –30%
    • Sizing
    • Design
    • Installation
  • 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
  • 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
  • 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 back drafting
  • Duct Tightness Tests
    • Post construction tests
    • Option 1
        • Leakage to outdoors: ≤8 cfm/per 100 ft 2 of conditioned floor area
        • OR
    • Option 2
        • Total leakage: ≤12 cfm/per 100 ft 2 of conditioned floor area
    Mandatory Requirements
  • Duct Tightness Tests
      • Rough-in test Options
      • Option 1
        • Total leakage ≤6 cfm/per 100 ft 2 of conditioned floor area
        • OR
      • Option 2
      • If air handler not installed at time of test total air leakage ≤4 cfm/per 100 ft 2
    Mandatory Requirements
        • Exceptions: Duct tightness test is not required if the air handler and all ducts are located within conditioned space
        • Thermal Boundary is also used to define whether testing is required.
          • Insulation installed on underside of roof sheathing, AHU and ducts in attic, can be considered within thermal boundary
  • Ventilation
    • Outdoor air intakes and exhausts shall have automatic or gravity dampers that close when the ventilation system is not operating
    Mandatory Requirements
  • Test Protocol
        • Pressurize the HVAC system, measure CFM of air required to reach pressure
        • Test at a pressure differential of 0.1 in w.g. (25Pa) across entire system, including manufacturer’s air handler enclosure
  • Test Equipment
  •  
  •  
  • Testing at rough-in
  • Testing Post Construction
  • Testing leakage to outside
  •  
  • Testing leakage to outside
  • Mastic Sealant Non-toxic – Low VOC Green credits Recommended Set time = 20 hours
  • 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
  • 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
  • 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.
  • 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.
  •  
  •  
  • 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
  •  
  •  
  •  
  • FLEX DUCT TO METAL
    • 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 draw band to hold outer sleeve (vapor barrier)
    Vapor barrier should be complete. All holes, rips, and seams must be sealed with mastic or approved tape
  •  
  • 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
  • Ts Ys & Ls
    • Use mesh tape to strengthen the joint where ducts of different shapes meet.
    • Seal all seams, even manufactured ones.
  •  
  •  
  • Seal Gores
  •  
  • Sealant applied, still leaks
  • FABRICATION & INSTALLATION GUIDELINES
    • The air handler box should be air-tight
  • 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.
  • Air Handler Leaks
  • Mechanical Systems & Equipment
  •  
  •  
  •  
  • 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
  • Boots
    • Seal all joints, including manufactured seams.
    • The transition between the duct and boot may require mesh tape.
  •  
  • AIRTIGHT DUCT SYSTEM
    • All Duct Types
    • Register boxes should be sealed to the drywall or floor with caulking or mastic
  • AIRTIGHT DUCT SYSTEM
    • All Duct Types
    • Register boxes should be sealed to the drywall or floor with caulking or mastic
  •  
  •  
  •  
  •  
  •  
  •  
  • SHEET METAL CONNECTIONS
    • Start the inner fitting into the outer fitting
    • Apply a 2” wide band of mastic 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 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
  •  
  •  
  • Locating ducts within thermal boundary
    • Within thermal boundary means within insulated space and within the air barrier boundary.
    • Attics and crawlspaces can be but are usually not conditioned space
    • Critical that space is truly indoors and sealed from unconditioned areas
    • Multi-level dwellings more easily accommodate ducts in conditioned space
  • Ducts in Unconditioned Space
    • Usually ducts are located in attics and crawlspaces
    • Big temperature differences increase conduction losses and loads
      • Long duct runs in attics lose 15%+ of cooling capacity before end
    • Convection losses by leakage
  • 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
    • Improve comfort
    • No Testing in 09 IECC
  •  
  •  
  •  
  •  
  •  
  •  
  •  
  • EXISTING HOMES
    • In existing homes, not unusual to find disconnected duct components, takeoffs loose from ducts or ducts disconnected from register boots
  • For Sealing Existing Systems
    • 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
  • 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.
  • 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
    • 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
    • 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
  •  
  •  
  •  
  •  
  •  
  • Oversizing
    • What do you get when you combine cognitive bias with inaccurate information?
  • Oversizing
    • Old Rules of Thumb
    • One Size Fits All
    • US Department of Energy
      • Most systems are oversized, increasing installation cost for every house
  • Oversizing
    • Sizing example
    • 2000 SF House with standard metal windows w/ .75 U-Value and .88 SHGC and 20% duct leakage
    • Calculated Sensible cooling load = 58880 Btu
  • 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
  •  
  • Oversizing
    • Sizing example
    • Same 2000 SF 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
  • Oversizing
    • Installation cost is higher
    • Operating cost over life of equipment is higher
    • Can cause comfort problems
    • Improvements in building envelope reduce loads
  • 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
  • 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.
  • 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
    • “ It’s tough to make predictions, especially about the future.”
    • - Yogi Berra
    • U.S. Dept of Energy
    • 30/30 Vision
    • 2012 IECC 30% More Stringent 2006 IECC
    • More verification testing
  • 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
  • Verifying Charge
  • 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
  • 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
  • Learn from the mistakes of others. You can't possibly live long enough to make them all yourself --Sam Levinson
  • Thank you for participating
    • Any questions
    • Please complete your evaluation sheets so we can plan future events