AHFC

Residential Energy Education

SOQ#12-R2D2-018

Methods of Analysis for Residential Structures

Combustion Safety Outline

Combustion Safety Testing - Course Outline

8 Hours

(4 in class, 4 in field)

A. Why is Combustion Safety Important?

1. Health and safety of occupants i.

Back drafting

1. Carbon Monoxide 2. Other combustion gasses

ii. Flame roll out

iii. Gas leaks

B. What is a Combustion Safety Test? (Short Version)

1. Check for gas leaks

2. Note any hazardous or unsafe conditions

3. Depressurize the CAZ (Combustion Appliance Zone) to worst case

4. Fire appliance, check for flame roll out

5. Check for spillage (back drafting)

6. Measure draft pressure

7. Measure CO in exhaust gasses

C. Heating System Basics

1. Appliance Types

i. Draft Types – Natural Draft

1. Photos

ii. Draft Types – Assisted Draft

1. Photos

iii. Draft Types – Power/Forced Draft

1. Photos

iv. Combustion Types – Open

1. Photos

v. Combustion Types – Closed

1. Photos

D. Basic Tools and Equipment

1. Digital Manometer

i. Measure draft of combustion appliance

ii. Measure depressurization inside the house

2. Digital combustion gas tester

i. Check Ambient CO levels inside the home ii.

Monitor technician safety during tests

iii. Check CO output of combustion appliances

3. Fuel Leak Detector

i. Check for propane, natural gas leaks or oil leaks

ii. All accessible lines, connections, connectors

4. Smoke pencil or generator

i. Check for spillage at combustion appliances

ii. Check door position for worst case depressurization

5. Your eyes

i. Observation is the best tool – can find things instruments and gauges will

miss

E. Test Procedures - Check for Gas Leaks

1. Gas Line Inspection – Objectives

i. Entire propane/gas line must be examined for leaks with detector

ii. Special attention around appliances, joints, valves and pilot lines

iii. Detect leak and isolate with soap bubble solution

iv. Flexible Gas Lines 1. Must be replaced if kinked, corroded, visible wear

2. Manufactured before 1973

3. Date stamped on date ring

4. Any soldered connections

v. Photo sniffing gas lines

vi. Inspect gas / propane system for leaks, potential problems

vii. Proper location of the fuel storage tank if present

viii. Verifying significant gas / propane leak (bubble solution)

ix. Visual signs of oil leaks, proper installation of fuel line to avoid damage,

line, filter

F. Common Unsafe Conditions

1. Find unsafe conditions with heating appliances and document

2. Flammable Materials

3. Signs of Soot/Flame Roll Out

i. Picture of flame roll out

4. Improper Chimney Clearance

i. Picture of improper clearance

5. No Shutoffs

i. Picture of Shutoffs

6. Heating Ducts in Garage

i. Picture of heat ducts in garage

7. Pressure Relief Valves

i. Picture of Relief Valve

8. Sources of Ignition on Garage Floor

9. Improper Vent Slope

i. Picture of Improper Vent Slope

10. Excessive Horizontal Run

i. Picture of Excessive Horizontal Run

11. Chimney Too Short

i. Picture of Chimney Too Short

12. Rusted or Damaged Chimney

i. Picture of Rusted or Damaged Chimney

13. Too Close to Openings

14. Other Problems

G. Combustion Safety Test Procedure

1. Scope

i. Preliminary and post installation safety inspection of all combustion

appliances

ii. Required on every appliance, type for every energy rating

2. Tests

i. Before any testing:

1. Take ambient CO measurement outside of house before entering

2. Monitor ambient CO levels in the CAZ (Combustion Appliance

Zone) before and during test for all appliances

3. If ambient levels exceed 35 ppm at any time, turn off appliance

immediately!

ii. CO measurement of each combustion appliance

iii. Draft measurement and spillage evaluation for each atmospherically

vented appliance

iv. Worst case pressure measurement for each combustion appliance zone

v. Results compared against Safety Action Level table

3. Combustion Safety Test Road Map

4. Spillage and Draft Test Objectives i. To determine if combustion appliance drafts under worst case

depressurization

ii. If fails under worst case, does appliance draft under natural conditions

iii. Draft pressure adequate based on temperature

iv. Does appliance spill flue gasses for more than one minute on start-up?

5. Combustion Safety Test Procedure

i. Designate Appliance

1. Smallest appliance in terms of input BTU/h is tested first

2. Remaining appliances tested in ascending order

3. Identify all combustion appliance zones

ii.

1 - Measure Base Pressure

1. After designating appliance, baseline pressure in the CAZ must be

determined

2. Exterior doors, windows, fireplace dampers shut

3. Set all combustion appliances to pilot or off

4. Water heater, unit heater, furnace, boiler, etc.

5. With home set up, measure and record CAZ WRT outside

2 – Establish Worst Case

1. After CAZ baseline is established, set up house in worst case

depressurization

2. Turn on clothes dryer and all exhaust fans

a. Clothes dryer not present (new construction) simulate with

150 cfm exhaust with a blower door, set up in the

house for a house installation and a garage for a garage

dryer installation

3. Check interior door positions to make CAZ pressure more negative

4. Turn on air handlers, one at a time, including HRVs if present, and

re-check door positions

5. Figuring Net Negative Pressure

a. Leave house set up in maximum negative pressure

b. Re-measure CAZ WRT outside pressure,

subtracting the base pressure recorded earlier

c. This is the net pressure

d. Record net pressure and compare with

CAZ Depressurization Limit Table

6. Net Negative Pressure Example

7. Net Negative Pressure Exercise 1

8. Net Negative Pressure Exercise 2

i. ii. CAZ Depressurization Limit Table Exercise 1

iii. CAZ Depressurization Limit Table Exercise 2

iv. When CAZ Depressurization Limits are Exceeded,

suggestions can include:

1. Provide makeup air 2. Modify building shell

3. Modify exhaust appliances

4. Bring depressurization to acceptable limits

7. 3 – Spillage Test

i. When house is under worst case depressurization, fire the first

combustion appliance

ii. Check for spillage at draft diverter for 1 minute

iii. Most appliances spill on startup

iv. Document time needed to establish draft

v. If spillage occurs more than 1 minute, appliance fails test, retest under

natural conditions

vi. Use mirror or smoke generator to check draft

vii. Spillage Testing Location

1. Individually vented appliances, check at draft diverter

2. Commonly vented appliances, check at water heater draft diverter

3. Picture of spillage location - water heater

4. Picture of spillage location – furnace

5. Pictures of spillage location – oil fired

6. Videos – gas and oil fired appliances failing draft test

viii. Multiple appliances present:

1. Once first appliance passes, fire all other connected appliances

simultaneously and test at each draft diverter

ix. If appliance fails worst case:

1. Turn appliance off

2. Turn off exhaust fans

3. Open interior doors

4. Allow vent to cool before re-testing

5. Resume entire test under natural conditions

6. Allow vent to cool before testing multiple appliances/shared vents

7. Videos – gas and oil fired passing natural conditions draft test

8. Draft Test

i. When spillage testing is complete, perform draft test

1. Drill hole in vent pipe

2. Do not drill holes in power vented or sealed combustion appliances

a. Vent under positive pressure

3. Test 1’ to 2’ after diverter or first elbow

a. Photo

4. Acceptable draft pressure based on outdoor temperature

5. Determining Acceptable Draft - Example 1 6. Determining Acceptable Draft - Exercise 1

7. Determining Acceptable Draft - Exercise 2

8. Determining Acceptable Draft - Exercise 3

9. Picture of draft test w/ manometer

10. Picture of Oil Fired Draft Test

11. Gas appliance draft test video

12. Oil appliance draft test video

ii. Cap hole in chimney when finished

1. Single wall pipe - Hi temp silicone sealant

9. CO Test

2. Double wall - lag screw w/ hi temp silicone

i. CO measured in undiluted flue gasses

ii. Measured with digital gauge in parts per million

iii. Do not drill holes in power vented or sealed combustion appliances

iv. Vent under positive pressure

v. Test CO in sealed combustion/power vent units at chimney termination

vi. CO measured at steady state operating efficiency

vii. Hole may be required in water heater draft diverter to reach undiluted flue

gasses

viii. Test both sides of water heater flue

ix. Test all furnace/boiler flue openings

x. Undiluted CO Locations

1. Picture of hole drilled in water heater draft diverter

2. Video – water heater CO test

3. Video – unit heater CO test

4. Video – oil fired boiler CO test

10. Ambient CO

i. Monitor ambient CO in breathing zone during test

ii. If exceeds 35 ppm, turn off appliance, ventilate space, evacuate building

iii. Building may be re-entered after levels drop below 35 ppm

iv. Appliance must be repaired prior to completing combustion safety testing

v. If CO exceeds 35 ppm during a natural conditions test, stop work until

problem is fixed

vi. Instruct homeowner to have appliance repaired prior to operation

11. 6 - Action Levels

ii. Combustion Safety Table Example 1 iii. Combustion Safety Table Exercise 1

iv. Combustion Safety Table Exercise 2

v. Retrofit Actions

12. Gas Ranges/Ovens

i. Unvented Appliances

1. NO unvented appliances allowed, except gas range/ovens

2. Must recommend exhaust ventilation where gas range/oven is

present

3. Range tops and ovens produce moisture, oxides of nitrogen, CO

4. Excess moisture bad for durability

5. CO detector always recommended

6. Homeowners should be instructed to use exhaust fan when

operating ranges/ovens

7. New ovens may take an extended period to reach steady state

ii. Gas/Propane Oven Test Procedure

1. Remove items/foil from oven before starting test

2. Set oven to highest setting, do not activate self-cleaning feature

3. Test oven for CO in flue, before dilution air

4. After 5 min. check for steady state

5. Picture of testing oven CO

a. Level 1 Action - 100 ppm to 300 ppm as measured you

must recommend a CO detector and service to the

customer

b. Level II Action - Greater than 300 ppm as measured,

you must recommend a CO detector, service and exhaust

ventilation to the customer

i. Minimum 25 cfm continuous, or 100 cfm

intermittent

13. CO Detectors

i. CO Detector Locations

14. Combustion Testing Checklist

Combustion Safety and Carbon Monoxide Protection Pre Post

1. Record outdoor CO Level 2. Record outdoor temperature 3. Ambient CO Level in House (if over 35, stop test and leave until problem fixed) 4. Use Gas Leak Detector, note any leakage areas below 5. Hazardous Condition? Visible signs of vent pipe leaks or damage? y/n y/n

6. Measure existing CAZ pressure (baseline), CAZ WRT outside (All doors open, all fans off, appliances off or "pilot")

7. Combustion appliance zone, designate appliance (Test smallest Btu appliance frist, then in ascending order)

8. Set up for Worst Case Depressurization, refer to next page If smoke comes out, leave door shut. If smoke goes into room, open door 9. Measure CAZ WRT Outdoors, 9a. Subtract Baseline from Worst Case for net negative pressure 9b. Look up CAZ depressurization limits (next page) 10. Fire appliance. Was flame roll out observed on start up? y/n y/n

11. Did the equipement spill flue gasses for more than one minute? (Test Spillage under worst case, then under natural if worst case fails) y/n y/n

(Check spillage at base of flue, for common vents check at water heater ) 12. Measure draft pressure in the vent WRT CAZ

(Test location 1' to 2' up from diverter) Minimum acceptable draft pressures: below 10º: -2.5Pa

10º to 90º: divide outside temp by 40 and subtract 2.75, Above 90º: -0.5Pa

13. Measure the CO in the exhaust gasses of the vented appliance (Measure at steady state, or 10 minutes, before draft diverter)

14. Measure the CO in the exhaust gasses of the kitchen stove (remove items from stove!) Set oven to highest setting. 100-300 ppm, must install CO detector and recommend service.

300ppm+ unit must be serviced prior to work. If still >300ppm, 25cfm continuous or 100 cfm intermittant ventilation installed

Gas oven (after 5 minutes) Any issues with cooktop burners? (flame impingement, yellow flame, sputtering) Ambient CO after 15 minutes Ambient CO after 45 minutes (if CO is over 5ppm after 15 minutes) Comments: Return House to Pre Test Conditions, Circle when Done DONE DONE

15. Combustion Testing Checklist Example 1 16. Combustion Testing Checklist Example 2

17. Hands On – 4 hours