COMBUSTION SAFETY BASICS

Transcription

1 COMBUSTION SAFETY BASICS Joe Konopacki Why Combustion Safety? Hydrocarbon fuels are hazardous Explosion or fire is possible Poor indoor air quality Exhaust byproducts are harmful or deadly Safe and efficient combustion Proper exhaust management Fire hazards happen thoughtlessly Combustibles set near fire Our clients want a safe & healthy home Communicate the level of risk & required action What to look for Combustion Process & CO Ambient (breathing zone) CO Gas/fuel Leaks Combustion Air CO production (on all gas appliances) CH 4 + 2O 2 2 H 2 O Exhaust Spillage signs Dryer Safety CO 2 Combustion is rarely perfect 1

2 CO Production Lack of oxygen = Incomplete combustion Inadequate combustion air High gas pressure Dirty, Misaligned burners Flame impingement Back drafting of combustion byproducts Carbon Dioxide (CO 2 ) --Nitrogen Oxide (NO) Carbon Monoxide (CO) --Sulfur Dioxide (SO 2 ) Ambient (breathing zone) CO CO Alarms ~3 yr Sensor Life! Ambient (breathing zone) CO Ambient CO Monitoring CO Alarm Young, old and ill feel effects first >5ppm can affect a fetus Position near source CO Detectors ~3 year typical sensor service life Some claim 10 year service TEST is for the battery, not the sensor Ambient (breathing zone) CO 2

3 Ambient (breathing zone) CO Ambient CO Monitoring CO Detector From time of entry BPI Ambient Limit: 35 ppm Ventilate Determine source Detecting Gas Leaks Gas/fuel Leaks Zero Out Outside or not? Adjust/Check Sensitivity Slowly move sensor around joints Check all accessible fuel pipe and joints Don t move appliances Natural gas rises -Propane falls Gas/fuel Leaks Reporting Gas Leaks Confirm with soap bubble solution? Tag it & Photo Leave a notice for homeowner Call out Pre-1973 Brass gas lines Gas Leaks Gas/fuel Leaks Most common issue Typical 1 leak per house average Not Normal Symptoms Respiratory allergic reactions Mold allergies Respiratory sensitivity 3

4 10/26/2016 Combustion Air Combustion Air Combustion Air from Inside Combustion Air from Outside 1 Total BTU to Volume of space 100, /. 2 / = 5, ft2 x 8 tall space 1 CO Production Gas Oven Testing. 1.5 / CO Production Gas Oven Testing Gas Oven CO Measurement Open window and/or turn On exhaust fan Test CO level in flue (undiluted stream) Set oven at highest setting (Broil) Monitor ambient CO during test (~2 ft away) Steady State Over 100 ppm is excessive 4

5 CO Production Gas Oven Testing CO Production Gas Oven Testing Gas Oven CO Measurement Record CO level at 10 minutes (Steady State) Report CO profile Recommend clean, tune & re-test Use exhausting range hood Typical high CO source in homes Types of Exhaust Atmospherically vented Natural Draft Uses metal exhaust pipe Inside air for combustion Hot exhaust rises due to greater buoyancy Open draft hood for dilution air Spillage possible here Types of Exhaust Induced Draft or Mechanically Assisted 5

6 Types of Exhaust Atmospherically vented Induced Draft or Mechanically Assisted Uses metal exhaust pipe Inside air for combustion Fan pulls combustion air through heat exchanger Fan does notpush exhaust up and out Measure CO Under or through draft hood Access undiluted flue gases Types of Exhaust Power Vented =1PVC pipe Inside air for combustion Cool exhaust pushed out Direct Vent= 2 PVC pipes (a.k.a. Sealed Combustion) Outside air for combustion Cool exhaust pushed out Check CO outside Types of Exhaust Power Vented =1PVC pipe Direct Vent= 2 PVC pipes 6

7 Types of Exhaust Proper Venting ¼ rise per foot min. for horizontal Min Vertical Rise (typically 3x vent diameter) With commonly vented units: Smaller Btu unit vented Above Larger Btu unit A Y-fitting assists natural upward draft Smaller unit Y s into Larger unit Improper Venting Blocked, or partially blocked, chimneys, vents or vent connectors No chimney liner for orphaned water heaters Improperly designed vent system An indirect route Negative slope T-fittings Lack of code compliance 7

8 Improper Venting 8

9 House Pressures House Pressures Stack Effect Creates negative pressure low in home Driven by temperature difference to outside Greater Stack pressure requires greater Draft pressure Wind Effect Positive pressure on Windward side induces spillage Negative pressure on Leeward side induces draft Make note of: Wind direction & speed Location of Flue Mechanical Fans Bath & kitchen fans ( cfm) Clothes Dryer ( cfm) Wood/gas burning stoves & fireplaces (300+ cfm) House Pressures Consider: Air Handler Duct Leaks Supply/Return Distribution Door Closures This is what leaky ductwork can do to your house No Leaks Supply Leaks Whole-house fan ( cfm) Return Leaks Room Imbalances 9

10 House Pressures House Pressures Exhaust Spillage Signs Depressurization Limit Negative Draft Pressure Limit is: Low for weak draft appliances High for stronger appliances Exhaust Spillage Signs Large exhaust fans Wind on chimney Room pressures Flue obstruction Negative CAZ Pressure Tug-of-War handicap Occasional Exhaust Spillage Flue geometry 10

11 Clogged flue FAU pressures Open returns Duct leaks Constant exhaust fans Tight home Exhaust Spillage Signs Consistent Exhaust Spillage Exhaust Spillage Signs Worst Case Pressure Testing The goal is to make the appliance fail. If it can be done on purpose, the homeowner may do it by accident. So how much negative pressure is too much? Exhaust Spillage Signs Worst Case Depressurization Typical Pressure Limit = -5 Exhaust Spillage Signs Spillage Test Fire appliance & check for spillage for 1 minute CDL Exceeded -FAIL- 11

12 Dryer Safety Vinyl or metalized Mylar will burn Fire hazard with gas dryers Recommend: Install metal flex or solid Clean entire line of lint No CO testing Dryer Safety Issues to Look For Dryer exhaust duct material Gas leaks Oven CO/ Range hood venting Combustion air requirements Melted grommets on water heater Corrosion near draft hood Evidence of flame roll out Benefits of CO Test Benefits of Detect Dangerous CO Malfunctioning unit Inefficient unit Cracked heat exchanger -$$ Recommend further analysis & repair Better understanding of house pressures on combustion exhaust flow Safety issues to look out for Dryer vent material Gas leaks Oven CO 12

13 QUESTIONS? 13