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Duct Sealing for Efficiency, Health, Durability and Safety. 2007 National Weatherization Training Conference Orlando, Florida. Building Performance & Comfort, Inc. Doug Garrett, CEM, CDSM Assoc. of Energy Engineers, Certified Energy Manager ACCA Certif. Instructor, Manual J, D, S
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Duct Sealing for Efficiency, Health, Durability and Safety 2007 National Weatherization Training Conference Orlando, Florida
Building Performance & Comfort, Inc. • Doug Garrett, CEM, CDSM • Assoc. of Energy Engineers, Certified Energy Manager • ACCA Certif. Instructor, Manual J, D, S • IECC Energy Code trainer for 4 years • Several IAQ/Mold Certifications • Former contractor • Consulting, diagnosing performance problems in homes and commercial buildings, training
How Much Does Air Weigh? • Standard air weighs 0.075 lbs./ft3 or 1.2 ounces • Standard Air (70° F, 50% RH, Sea Level) • A 5 ton A/C unit moves 2,000 cfm
How Much Does Air Weigh? 5 TON A/C UNIT: 2,000 CFM X 0.075 lbs/ft3 = 150 lbs/min. 150 lbs/min x 60 min = 9,000 lbs/hr 4.5 TONS/HR
How Does Air Move? • All natural air motion is due to a difference in pressure, air moves from points of high pressure to points of low pressure • Another answer would be that based on the duct designs and installation I’ve seen I can’t believe that it does move as well as it does in most homes!
Like the Crew This Duct Has Had to Chinch Up Its Belt A Bit 3”?
Just So You’ll Realize They do It to Rich Folks Houses Too!!
Leaky Supply Ducts and Panned Stud Bays/Floor Joists. Don’t worry, this is only a $2 Million dollar home!
Air Tight Ducts • Amount of Duct Leakage • Impacts of Duct Leakage on EER and Capacity • Impacts of Duct Leakage on Moisture and IAQ • Safety Concerns Related to Duct Leakage
How Much Do Ducts Leak? • Studies by utilities, cities and universities found leakage averaging 30% of rated airflow! • U.S. Dept. of Energy research found the same leakage across the nation. • This costs us all a fortune, as in Billions of dollars each year!
What Types of Ducts Leak? • All ducts were found to leak about the same amount. • Flex duct and metal ducts leak at connections. • Duct board can leak at any unsealed seam. • All building chases used as ducts leak like cheese cloth!
What Are the Impacts of Duct Leakage? • Forces contractor to increase tonnage to compensate for unknown loss of capacity. • Slashes efficiency of equipment! • Costs builders, home owners billions. • Increases peak demand for electricity. • Worst impacts when conditions outside are worst! • Back Drafting of Combustion Appliances!
Duct Sealing • UL-181-A for metal ducts and duct board. • UL-181-B for flex ducts. • Tapes and mastics are both listed and available. Much better performance than “duct tape.” • Cloth Duct Tape is illegal!
HVAC System: • In a 3 Month Accelerated Aging Test simulating 30 Years in the field, U.S. DOE found Failure in: • Cloth Duct Tape = 7 Days • UL-181B-FX Tape = 10 Days • UL-181 B-FX Foil Tape = 10 days • UL-181-A and BMastic = No Failures!!
Where and How to Seal Ducts: • Seal the fitting to the plenum or drywall with UL181 mastic. • Seal the inner liner to the fitting with UL 181 mastic and a tie strap. • Seal all connections, fittings, seams, joins and the air handler with mastic. • Never ever use a building chase as a duct!
Duct Leaks • Seal all connections, start collars, boots etc with latex water based mastic like RCD #6 • Seal all sides of the return with sheetrock, and then paint mastic on all cracks, seams, joints, etc. • On Up flow return platforms seal the platform from underneath or inside.
Are you Pooky challenged? Contributed by: Tom Turner Last week I went on an inspection at 9:30 am and in the process managed to smear pooky (mastic) over two legs and the seat of my jeans. As I work for the City and live in Cedar Park (too far away to go home and change), I just worked the rest of the day letting the mastic set up figuring I had ruined a pair of pants.
That evening at about eight o'clock I put the pants in a full tub of washing machine water and let them soak about 45 minutes. I then added a sample packet (one wash load) of Oxyclean and ran the pants through one wash cycle. Immediately afterthe wash cycle ended and drained (no rinse) I then ran the washer full of water again and added my normal detergent. The washer went through the normal wash and rinse cycles and the pants came out clean. I tried this a second time and it worked on a second pair of old pants. This may be a help to those who install on a daily basis in saving some money replacing pants and shirts.
That Concludes Today’s Program, Thanks for Listening!