Combustion Appliances

1. Combustion Appliances WEATHERIZATION ENERGY AUDITOR SINGLE FAMILY WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012

2. Learning Objectives • By attending this session, participants will be able to: • Explain the basic principles of combustion, distribution, and venting and be able to recognize safety-related problems. • Describe the health and safety issues related to combustion equipment. • List the basic steps of visual and diagnostic combustion appliance safety and efficiency inspection. • Cite test procedures for vented and non-vented appliances. • Summarize the relationship between combustion safety problems and poorly designed or non-code-compliant vent systems. • Describe worstcase combustion appliance zone testing.

3. Why Test Combustion Appliances? We test to assure: • Health and safety. • Building integrity. • Comfort. • Energy efficiency. Photo courtesy of New River Center for Energy Research and Training (NRCERT)

4. Combustion Basics Combustion appliances

5. The Combustion Triangle Combustion appliances Requirements for Combustion (Burning):

6. Triangle of Combustion Products Complete Combustion Results in:

7. Complete Combustion Complete Combustion Occurs… • When all the fuel is burned with sufficient oxygen to produce carbon dioxide and water vapor. Combustionby-products

8. Carbon Monoxide from Incomplete Combustion CO occurs when: • The ratio of fuel to oxygen is either too high to permit the complete formation of CO2 or... • The temperature is too low to permit complete burning to occur. It is caused by: • Too much fuel for the amount of oxygen. • Not enough oxygen for the amount of fuel. • Not enough heat (flame impingement).

9. Combustion, Distribution & Venting Vent Supply Air Combustion Gases Return Air Dilution Air Heat Exchanger Gas Valve Main Burner Combustion Air

10. What to Inspect - Visual What do we inspect on combustion appliances? • Chimney safety • Vent pipes • Wiring • Heat exchanger • Distribution systems • Combustion air Photo courtesy of PA Weatherization Training Center

11. Fuel Leak Testing #1 Use a calibrated gas leak detector to locate fuel leaks. Photo Courtesy of NRCERT Bacharach www.bacharach-inc.com

12. Fuel Leak Testing #2 Combustion appliances Photos Courtesy of NRCERT Test all joints, valves, and fittings. Use soap bubbles to confirm a leak.

13. Fuel Leak Testing #3 Photos Courtesy of NRCERT Gas leak detector forgas and propane. Visual inspection and the personal sniff test for fuel oil.

14. Inspection – Wiring • Is insulation on wiring missing or deteriorated? • Is the heating system on its own circuit? • Are wires properly clamped, connected, and enclosed? Photos Courtesy of NRCERT

15. Clearance to Combustibles Combustion appliances Photo Courtesy of NRCERT

16. Combustion Air • NFPA-54 states that combustion air must be provided for any combustion zone where the collective fuel input exceeds 1,000 Btu per 50 cubic ft. • Make-up air can be provided from outdoors or from other zones of the building. Photo Courtesy of NRCERT

17. Filter Replacement Combustion appliances Change out the furnace filter and educate the client about checking it periodically. Photo Courtesy of NRCERT Photo Courtesy of PA Weatherization Training Center

18. Blower Maintenance Combustion appliances Clean the blower. Photo Courtesy of PA Weatherization Training Center Photo Courtesy of NRCERT

19. Combustion Safety Problems Combustion appliances Photos Courtesy of PA Weatherization Training Center Rust on the draft hood of a natural gas furnace is evidence of severe spillage of flue gases. Soot stains at the inspection port of an oil fired boiler indicate the need for a tune up.

20. What to Test – Diagnostics What do we test on combustion appliances? • Fuel leaks • Fuel input rate • Sufficient combustion air • Worst case draft • Carbon monoxide • Combustion efficiency Photo Courtesy of NRCERT

21. Testing Equipment - Criteria Combustion appliances Combustion analyzers should be able to measure: • Flue gas oxygen content • Flue gas temperature • Ambient temperature • Flue gas carbon monoxide • Combustion efficiency • Flue gas carbon dioxide content • Flue gas air-free or as measured CO content Photo courtesy of Bacharach Inc.

22. Selected Testing Equipment Combustion appliances Draft gauge Smoke tester (for oil) Photo courtesy of Bacharach Inc. Photo courtesy of Bacharach Inc. Digital probe thermometer Inspection mirror Photo courtesy of Bacharach Inc. Photo courtesy of Omni Controls

23. Testing Equipment Combustion appliances Photo Courtesy of NRCERT If you’re not testing, you're guessing!

24. Unvented Space Heaters Combustion appliances Photos Courtesy of NRCERT 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.

25. Visual Assessment –Space Heaters Combustion appliances • WPN 11-6: Space Heater Policy • No weatherization work allowed where unvented gas or liquid fuel space heater is primary heat source. • Removal and replacement of such heaters with vented, code-compliant heating systems prior to weatherization is strongly encouraged. • Input rating must be at or below 40,000 BTU/hr. • WAP funds may only replace primary heating system, e.g. unvented with vented, code-compliant system. May not replace unvented space heaters left in home as secondary units with code-compliant unvented units. • Mobile homes must be vented outside. Photo Courtesy of NRCERT

26. Cook Stove Testing Why Test Gas Cook Stoves? • Elevated levels of CO are common. • People often use them as a heat source. • CO kills. • Knowledge implies action. Photo Courtesy of NRCERT

27. Gas Cook Stove Testing Mobile Home Assessment Photos courtesy of NRCERT Measure the CO content in ambient air and visually assess the flame and condition of the burners.

28. Gas Cook Stove Testing Mobile Home Assessment Photos courtesy of NRCERT Prepare the oven for a test by removing stored items, aluminum foil, etc. Insert the probe of the analyzer into the oven vent and read the CO content after the oven has warmed.

29. Furnace Testing Protocol Furnaces must be tested to assess: Safety (fuel leaks, clearances, etc.). Flue gas temperatures. Oxygen (O2) or Carbon dioxide (CO2). Carbon monoxide (CO) levels. Draft. Condition of the heat exchanger. Combustion appliances Single wall flue for oil heat. Open-ended duct Photos Courtesy of PA Weatherization Training Center

30. Furnace Testing Methods - Visual Combustion appliances Check for: • Dirt and debris. • Burner alignment. • Soot, evidence of flame roll-out. • Heat-exchanger condition. • Vent pipe and roof termination. • Gas or oil leaks. • Wiring condition. • Condition of air filter. Cracked heat exchanger Photo Courtesy of NRCERT

31. Heat Exchanger Leakage Testing Combustion appliances Test methods: • Look for flame damaged areas on the heat exchanger. • Look for rust on the burner ports. • Measure flue gas concentration before and after blower starts. • There should be no more than 1% oxygen change when the blower starts. • Observe change in draft, CO or flame when blower turns on. • Look for flame damaged areas on the heat exchanger. Damaged area of heat exchanger Photo Courtesy of NRCERT

32. Inspection – Heat Exchanger • Use a strong light and an inspection mirror. • Is the heat exchanger rusty? • Are there cracks? Photo courtesy of Bacharach Inc.

33. Worst Case Combustion Safety Testing • Find the worst case depressurization in the CAZ. • Under worst case conditions conduct: • Spillage test • Draft test • CO test • Perform at the time of the audit and at the end of each work day. • Deactivate appliances until hazard is fixed • Conduct these tests for vented systems only!

34. Setting Up Worst Case Conditions • Record outdoor temperature. • Clean dryer lint filter and furnace filter. • Deactivate all combustion appliances. • Close all exterior doors and windows. • Open interior doors containing exhaust fans. • Close all other interior doors.

35. Conducting a Worst Case Test • Record the pressure difference of the CAZ with respect to outdoors using a manometer. • Operate all exhaust devices. • Record the pressure difference of the CAZ with respect to outdoors. • Conduct CO and spillage tests under worst case conditions. • Open and close interior doors (including door to CAZ). • Repeat for all other vented appliances. • Return dwelling, exhaust fans, and combustion appliances to normal settings.

36. Test for Spillage Combustion appliances No spillage after two minutes of operation Smoke stick at draft diverter Photo Courtesy of PA Weatherization Training Center

37. Spillage, Draft and CO Spillage • Test at vent openings, i.e., dilution air openings and barometric damper with smoke. CO • Test at appliance breech between appliance and first opening in vent connect or directly above heat exchanger. • Condensing gas appliances – Test at vent termination.

38. CO, Draft and Steady State Efficiency Combustion appliances Atmospheric Furnace 80+ Induced Draft Furnace CO & Draft Draft CO Illustrations courtesy of Corporation for Ohio Appalachian Development (COAD)

39. CO and Draft Test Locations #1 Combustion appliances 90+ Condensing Furnace Floor Furnace CO & Draft CO Draft Illustrations courtesy of Corporation for Ohio Appalachian Development (COAD)

40. CO and Draft Test Locations #2 Combustion appliances Fuel Oil Furnace Barometric Damper CO Draft Photo courtesy of NRCERT Illustration courtesy of Corporation for Ohio Appalachian Development (COAD)

41. Carbon Monoxide Action Levels Combustion appliances

42. Combustion Safety Problems - Fixes Solve excessive depressurization or inadequate draft: • Repair chimney obstructions, disconnections, or leaks. • Properly size the vent, connector, or liner. • Install a metal chimney liner and/or a wind-rated chimney cap. • Seal leaks in the return ducts of the CAZ. • Balance supply and return air by adding new returns or by adding passive return air openings to the main body of the house. • Reduce capacity of large exhaust fans. • Provide make-up air for dryers and exhaust fans. • Provide combustion air inlet to CAZ.

43. Open Returns Combustion appliances Open return Disconnected draft hood Photo Courtesy of PA Weatherization Training Center

44. Measuring BTU Input Combustion appliances Clocking the Gas Meter Time one revolution of smallest dial • Turn on only the unit to be measured. Others should be off. • Time one revolution of smallest dial, and compare to a calibration chart. • Any discrepancy with the rated input should be within 10% of the input rating. Photos courtesy of NRCERT

45. What’s Wrong with this Picture? Combustion appliances From hot water tank To chimney From furnace Photo Courtesy of PA Weatherization Training Center

46. Chimney and Vent Connectors Combustion gases mixed with room air Draft diverter Vent Chimney Dilution air Draft hood Water heater Gas heating appliance

47. Venting Systems A venting system should: • Carry all combustion byproducts to the outdoors. • Establish draft quickly. • Be properly sized with minimal restrictions. • Have long durability (corrosion resistance). • Not overheat surrounding materials. • Have adequate make-up air.

48. Chimneys and Vents From hot water tank Single wall vent Chimney From furnace Photo Courtesy of PA Weatherization Training Center

49. Vent Types Masonry chimney and B-vent • Masonry chimneys. • Type B vents – double wall, round. • Type B-W vents – double wall, oval. • Type L vents – more heat, corrosion resistant. • Single wall metal – interior only. • Plastic pipe vents – low temp condensing furnaces. Photo courtesy of NRCERT

50. Factors That Affect Vent Operation • 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 CAZ See a problem here? Photo Courtesy of PA Weatherization Training Center