Chimney Physics Ashley Eldridge Chimney Safety Institute of America This session is designed to help technicians understand how pressures (air flowing in and out of the home) can cause fuel burning equipment to malfunction. There will be case studies and solutions. 2017 HPBExpo Education Sponsored by: 2/20/2017 Chimney Physics An Overview Brought to you by the Chimney Safety Institute of America © CSIA 2017 Today We Will Discuss How the Laws of Physics Affects Air Movement in the Home. We Will Cover: - The House As a System -Combustion Air Requirements -Indoor Air Quality -UiUsing t hThe Too ls o fhTdf the Trade -Troubleshooting Vented Appliances 1 2/20/2017 Course Content and Format The longer Chimney Physics class has; • More material to provide a thorough understanding of the issues. • Practical exercises to give you real world experience using the equipment necessary to complete the job. • Handouts and materials that can be used in the field. Who Should Be Taking the Course? • This course is perfect for chimney sweeps, hearth products installers, HVAC technicians, designers, architects, and building officials. • Anyone that is interested in having a better understanding of indoor air quality, house air flow and pressure issues, combustion air supply, vent design diagnosis of venting issues and implementation of solutions. What Will I Take Home From This Class? • Useful information that you can apply right away. • A hunger to learn more and a desire to sign up for the extended class. 2 2/20/2017 Chimney Safety Institute of America Reference Materials and Contributors “Venting Design Specialist Training Manual”, Hearth Education Foundation. “The Fireplace in the house as a system”, John Gulland. Magic Sweep Corporation, Jim Brewer Jack Pixley Sweeps, Inc., Jack Pixley National Fire Protection Association, NFPA 211 Standard for Chimneys, Fireplaces, Vents, and Solid Fuel-Burning Appliances, 2016 Edition Watch for This Image • This icon means there is a handout to discuss. Seminar Topics • Venting designs • Neutral pressure plane • Flue sizing • Venting problems • System location • Diagggnostic testing • Pressure • Sooting • Draft & flow • Ventilation • Combustion air • Blower doors • Air openings • Air flow 3 2/20/2017 Venting Designs Venting systems for Atmospherically vented appliances include; •B-vent •Direct vent •Factory built chimneys •Masonry chimneys Table of Contents Obvious Problems B-vent Approved for many gas-fired hearth appliances such as: •Gas inserts •Gas stoves •Gas fireplaces 4 2/20/2017 B-vent • B-vent is constructed of two walls separated by a small air space. – Inner wall is aluminum. – Outer wall is galvanized. • B-vent is inexpensive and easy to install. • Tested to UL 441 – gas vents. B-vent • B-vent is not approved for use with vented gas logs. • Flue gases could easily exceed the 470 degree temperature test of UL 441. B-vent – Outdoors ? • B-vent is not recommended for outdoor installation blbelow t he roo fline. • Low insulating value allows rapid cooling of flue gases. 5 2/20/2017 Direct Vent • Direct vent appliances draw their combustion air from the outdoors, and exhaust combustion ppyroducts directly to the outdoors. Co-linear Direct Vent • Co-linear DV systems use one pipe for exhaust and another fbiifor combustion air. • Practical for: – Inserts & Hearth stoves – HVAC systems Co-axial Direct Vent • Co-axial DV systems use a “pipe within a pipe” design. • Inner pipe is for the exhaust, and the outer pipe is for combustion air. © CSIA 2013 6 2/20/2017 Direct Vent Advantages • Obtains all combustion air from outdoors, making them an excellent choice for modern,,g tight homes. • Highly spillage resistant – up to 25 pascals negative. DV Installation Flexibility • Short horizontal termination (through the wall). • Vertical installations (through the ceiling). Factory Built Chimneys Factory built chimney can be used to vent many appliance types such as: – Fireplaces. – Wood/coal stoves. – Gas logs. •Tested to UL 103. 7 2/20/2017 Factory Built Chimney • Three “general” types of factory built chimney are: – Air cooled. – Air insulated. – Mass insulated. • Some designs utilize a combination of methods. Air Cooled • Sometimes called “thermosyphon”. • Three separate walls create two air channels. • Designed to circulate air through the channels. • Continuous convection cools the flue gases. • Originally intended for fireplaces. • Not recommended for “air-tight” stoves. Air Insulated • Three walls spaced apart to create two separate channels of dead air. • Dead air space is a relatively good insulator and helps keep the flue gases warm. 8 2/20/2017 Mass Insulated • Stainless steel inner liner. • Outer liner generally stainless but may be galvanized. • Has 1 to 2 inches of insulating material between the walls. • Insulation keeps the flue gases warm. Factory Built Fireplace Chimney – A Special Case Included in UL 127 as part of the fireplace Fireplace Chimney • A factory-built fireplace chimney can only be used with the specific mo de ls o f fireplaces with which they have been tested. 9 2/20/2017 Masonry Chimneys Masonry chimneys, like factory built chimneys, can be used to vent many appliance types such as: – Fireplaces – Wood/coal stoves – Gas logs – Oil & gas appliances Masonry Chimneys Masonry chimneys can be built of; –Brick. – Block. – Stone. They are not tested or listed, but should be built according to local code. Masonry Chimneys • Modern masonry chimneys should be lined with a liner suitable for thlihe appliance. • Liners can be: – Fireclay tile. – Cast-in-place. – Stainless. – Aluminum. Vitreous tile liner 10 2/20/2017 Chimney Liners - 1777 • Chimney liners listed to UL 1777 can be used for all residential type appliances. • This would include: – Solid fuel. – Oil. –Gas. Chimney Liners - Oil • Chimney liners tested to the temperature limits of UL 641 can only be used with appliances app roved for use with L-vent or B-vent. • This would include: – Some oil appliances – Most gas appliances Chimney Liners – Gas • Chimneys liners tested to the temperature limits of UL 441 can only be used with gas appliances app roved for B-vent. • This would include: – Gas stoves –Gas inserts – Gas Furnaces or boilers 11 2/20/2017 What Does It Mean, The “House As a System”? • The house as a system refers to how air moves in, out and aroundhd a house. • Air moves in and out of a house through the building envelope. Building Envelope The “building envelope” or “thermal envelope” of a house is made up of the surfaces that enclose conditioned (heated or cooled) space. Tighter Homes Have Caused Indoor Air Quality Problems • Because homes are built tighter, there is less natural “air leakage” througggh the building envelope. Less air movement allows pollutants to be trapped inside the house. Less air exchange also means less make up air available for combustion appliances. 12 2/20/2017 Why Is Indoor Air Quality an Issue? • Studies show that Americans spend 80-90% of their time indoors. • The number of people suffering from asthma and other respiratory diseases are on the rise. • Homes are being constructed with tighter building envelopes. • There is a legitimate concern about off-gassing from construction products. Major Contaminants Affecting Indoor Air Quality • Radon • Carbon Dioxide (CO ) • Formaldehyde 2 • Carbon Monoxide • LdDtLead Dust (CO) • Soot - Particulates • Nitrogen Dioxide • Tobacco Smoke (NO2) • Ozone • Sulfur Dioxide (SO2) • Asbestos • Biological Contaminants Regulations on Pollutants for Homes • There are none!!! • As of today, there are no enforceable codes or standards that outline what are acceptable levels of indoor air pollutants. • Some organizations have developed guidelines for various pollutants. 13 2/20/2017 Chart of What Different Organizations Allow Flue Sizing Requirements • Good venting systems rely on properly sized flues. •Manyygyp venting system problems are the result of improper sizing. • Sizing recommendations can be found in manufacturers information or building codes. Table of Contents Masonry Fireplaces • General “rule of thumb” says area of the fireplace flue should be at least 1/10th of the firepppglace opening. • New requirements (NFPA & ICC) – Round flues should be 1/12th – Square or rectangle should be 1/10th – Rectangles greater than 2 to 1 aspect should be 1/8th 14 2/20/2017 Code Language Round Square 1/12th 1/10th Rectangle Long Rectangle 1/10th 1/8th Factory Built Fireplaces • Flue sizing for factory built fireplaces should be in accordance with the manufacturers installation instructions. • Most factory built fireplaces use an 8” round flue, but some may be larger. Fireplaces With Gas Logs • Follow the gas log manufacturers’ directions for flue sizing. • Many manufacturers will use NFPA 54 (National Fuel Gas Code) recommendations based on BTU input and chimney height. 15 2/20/2017 Sample NFPA 54 Table Height Minimum Permanent Round Opening of 8 in 13 in 20 in 29 in 39 in 51 in 64 in Flue Appliance Input Rating (BTU X 1000) (()Ft) 6 7.8 14 23.2 34 46.4 62.4 80 8 8.4 15.2 25.2 37 50.4 68 86 10 9 16.8 27.6 40.4 55.8 74.4 96.4 15 9.8 18.2 30.2 44.6 62.4 84 108 20 10.6 20.2 32.6 50.4 68.4 94 122.2 30 11.2 21.6 36.6 55.2 76.8 105.8 138.6 Solid Fuel Appliances • Minimum area of the flue should be at least as large as appliance flue collar outlet. • Maximum area of the flue should not exceed three times the area of the appliance flue collar outlet for interior chimneys. • For exterior chimneys it should not be more than twice the area. Gas Hearth Appliances • Flue sizing should be in accordance with the manufacturer’s recommendations. • Generally they will range from 3 ” to 8”. 16 2/20/2017 Chimney or Vent Location • The location of the venting system will have a dramatic effect on appliance performance.