This appendix is not a part of the requirements of this code and is included for informational purposes only.
This appendix is an excerpt from the 2018 International Fuel Gas Code, coordinated with the section numbering of the International Residential Code.
About this appendix: Appendix D provides procedures for testing and inspecting existing gas appliance installations for safe operation.
The inspection procedures include measuring for fuel gas and carbon monoxide (CO) and will require the use of a combustible gas detector (CGD) and a CO detector. It is recommended that both types of detectors be listed. Prior to any inspection, the detectors should be calibrated or tested in accordance with the manufacturer's instructions. In addition, it is recommended that the detectors have the following minimum specifications.
- PPM: Numeric display with a parts per million (ppm) scale from 1ppm to 900 ppm in 1 ppm increments.
- LEL: Numeric display with a percent lower explosive limit (% LEL) scale from 0 percent to 100 percent in 1 percent increments.
- Audio: An audio sound feature to locate leaks.
- PPM: For measuring ambient room and appliance emissions a display scale in parts per million (ppm) from 0 to 1,000 ppm in 1 ppm increments.
- Alarm: A sound alarm function where hazardous levels of ambient CO is found (see D.2 for alarm levels)
- Air Free: Capable of converting CO measurements to an air free level in ppm. Where a CO detector is used without an air free conversion function, the CO air free can be calculated in accordance with Note 3 in Table D.6.
Prior to entering a building, the inspector should have both a combustible gas detector (CGD) and CO detector turned on, calibrated, and operating. Immediately upon entering the building, a sample of the ambient atmosphere should be taken. Based on CGD and CO detector readings, the inspector should take the following actions:
- The CO detector indicates a carbon monoxide level of 70 ppm or greater 1. The inspector should immediately notify the occupant of the need for themselves and any building occupant to evacuate; the inspector shall immediately evacuate and call 911.
- Where the CO detector indicates a reading between 30 ppm and 70 ppm1. The inspector should advise the occupant that high CO levels have been found and recommend that all possible sources of CO should be turned off immediately and windows and doors opened. Where it appears that the source of CO is a permanently installed appliance, advise the occupant to keep the appliance off and have the appliance serviced by a qualified servicing agent.
- Where CO detector indicates CO below 30 ppm1 the inspection can continue.
- The CGD indicates a combustible gas level of 20-percent LEL or greater. The inspector should immediately notify the occupant of the need for themselves and any building occupant to evacuate; the inspector shall immediately evacuate and call 911.
- The CGD indicates a combustible gas level below 20-percent LEL, the inspection can continue.
If during the inspection process it is determined a condition exists that could result in unsafe appliance operation, shut off the appliance and advise the owner of the unsafe condition. Where a gas leak is found that could result in an unsafe condition, advise the owner of the unsafe condition and call the gas supplier to turn off the gas supply. The inspector should not continue a safety inspection on an operating appliance, venting system, and piping system until repairs have been made.
- Appliance Connector. Verify that the appliance connection type is compliant with Section G2422 of the International Fuel Gas Code. Inspect flexible appliance connections to determine if they are free of cracks, corrosion and signs of damage. Verify that there are no uncoated brass connectors. Where connectors are determined to be unsafe or where an uncoated brass connector is found, the appliance shutoff valve should be placed in the off position and the owner notified that the connector must be replaced.
- Piping Support. Inspect piping to determine that it is adequately supported, that there is no undue stress on the piping, and if there are any improperly capped pipe openings.
- Bonding. Verify that the electrical bonding of gas piping is compliant with Section G2411 of the International Fuel Gas Code.
- Preparing for Inspection. Shut off all gas and electrical power to the appliances located in the same room being inspected. For gas supply, use the shutoff valve in the supply line or at the manifold serving each appliance. For electrical power, place the circuit breaker in the off position or remove the fuse that serves each appliance. A lock type device or tag should be installed on each gas shutoff valve and at the electrical panel to indicate that the service has been shut off for inspection purposes.
- Vent System Size and Installation. Verify that the existing venting system size and installation are compliant with Chapter 5 of the International Fuel Gas Code. The size and installation of venting systems for other than natural draft and Category I appliances should be in compliance with the manufacturer's installation instructions. Inspect the venting system to determine that it is free of blockage, restriction, leakage, corrosion, and other deficiencies that could cause an unsafe condition. Inspect masonry chimneys to determine if they are lined. Inspect plastic venting system to determine that it is free of sagging and it is sloped in an upward direction to the outdoor vent termination.
- Nondirect-vent Appliances. Determine that non-direct vent appliance installations are compliant with the combustion air requirements in Section G2407 of the International Fuel Gas Code. Inspect any interior and exterior combustion air openings and any connected combustion air ducts to determine that there is no blockage, restriction, corrosion or damage. Inspect to determine that the upper horizontal combustion air duct is not sloped in a downward direction toward the air supply source.
- Direct Vent Appliances. Verify that the combustion air supply ducts and pipes are securely fastened to direct vent appliance and determine that there are no separations, blockage, restriction, corrosion or other damage. Determine that the combustion air source is located in the outdoors or to areas that freely communicate to the outdoors.
- Unvented Appliances. Verify that the total input of all unvented room heaters and gas-fired refrigerators installed in the same room or rooms that freely communicate with each other does not exceed 20 Btu/hr/ft3.
- Flooded Appliances. Inspect for flood damage to the appliance. Signs of flooding include a visible water submerge line on the appliance housing, excessive surface or component rust, deposited debris on internal components, and mildew-like odor. Inform the owner that any part of the appliance control system and any appliance gas control that has been under water must be replaced. Flood-damaged plumbing, heating, cooling and electrical appliances should be replaced.
- Flammable Vapors. Inspect the room/space where the appliance is installed to determine if the area is free of the storage of gasoline or any flammable products such as oil-based solvents, varnishes or adhesives. Where the appliance is installed where flammable products will be stored or used, such as a garage, verify that the appliance burner(s) is not less than 18 inches above the floor unless the appliance is listed as flammable vapor ignition resistant.
- Clearances to Combustibles. Inspect the immediate location where the appliance is installed to determine if the area is free of rags, paper or other combustibles. Verify that the appliance and venting system are compliant with clearances to combustible building components in accordance with Sections G2408.5, G2425.15.4, G2426.5, G2427.6.2, G2427.10.5 and other applicable sections of Section G2427.
- a. Inspect burners and crossovers for blockage and corrosion. The presence of soot, debris, and signs of excessive heating are potential indicators of incomplete combustion caused by blockage or improper burner adjustments.
- c. Metallic and nonmetallic hoses for signs of cracks, splitting, corrosion, and lose connections.
- d. Signs of improper or incomplete repairs
- e. Modifications that override controls and safety systems
- f. Electrical wiring for loose connections; cracks, missing or worn electrical insulation; and indications of excessive heat or electrical shorting. Appliances requiring an external electrical supply should be inspected for proper electrical connection in accordance with the National Electric Code.
- Placing Appliances Back in Operation. Return all inspected appliances and systems to their preexisting state by reinstalling any removed access panels and components. Turn on the gas supply and electricity to each appliance found in safe condition. Proceed to the operating inspections in D.5 through D.6.
- Flame Appearance. Visually inspect the flame appearance for proper color and appearance. Visually determine that the main burner gas is burning properly (i.e., without floating, lifting or flashback). Adjust the primary air shutter as required. If the appliance is equipped with high and low flame controlling or flame modulation, check for proper main burner operation at low flame.
- Appliance Shutdown. Adjust the thermostat or other control device to shut down the appliance. Verify that the appliance shuts off properly.
- Preparing for Inspection. Close all exterior building doors and windows and all interior doors between the space in which the appliance is located and other spaces of the building that can be closed. Turn on any clothes dryer. Turn on any exhaust fans, such as range hoods and bathroom exhausts, so they will operate at maximum speed. Do not operate a summer exhaust fan. Close fireplace dampers and any fireplace doors.
- Placing the Appliance in Operation. Place the appliance being inspected in operation. Adjust the thermostat or control so the appliance will operate continuously.
- After 5 minutes of main burner operation, check for spillage using smoke.
- Immediately after the first check, turn on all other fuel gas burning appliances within the same room so they will operate at their full inputs and repeat the spillage test.
- Shut down all appliances to their standby mode and wait for 15 minutes.
- Repeat the spillage test steps a through c on each appliance being inspected.
- Set initial test condition in accordance with D.5.2 (1).
- Place the appliance(s) being inspected in operation. Adjust the thermostat or control so the appliance(s) will operate continuously.
- Open the door between the space in which the appliance(s) is located and the rest of the building. After 5 minutes of main burner operation, check for spillage at each appliance using smoke.
- Turn on any other central heating or cooling air handler fan that is located outside of the area where the appliances are being inspected. After 5 minutes of main burner operation, check for spillage at each appliance using smoke. The test should be conducted with the door between the space in which the appliance(s) is located and the rest of the building in the open and in the closed position.
- Return doors, windows, exhaust fans, fireplace dampers, and any other fuel gas burning appliance to their previous conditions of use.
- If, after completing the spillage test it is believed sufficient combustion air is not available, the owner should be notified that an alternative combustion air source is needed in accordance with Section G2407 of the International Fuel Gas Code. Where it is believed that the venting system does not provide adequate natural draft, the owner should be notified that alternative vent sizing, design or configuration is needed in accordance with Chapter 24 of the International Fuel Gas Code. If spillage occurs, the owner should be notified as to its cause, be instructed as to which position of the door (open or closed) would lessen its impact, and that corrective action by a HVAC professional should be taken.
The following appliance-specific inspections are to be performed as part of a complete inspection. These inspections are performed either with the appliance in the off or standby mode (indicated by "OFF") or on an appliance that is operating (indicated by "ON"). The CO measurements are to be undertaken only after the appliance is determined to be properly venting. The CO detector should be capable of calculating CO emissions in ppm air free.
- OFF. Verify that an air filter is installed and that it is not excessively blocked with dust.
- OFF. Inspect visible portions of the furnace combustion chamber for cracks, ruptures, holes, and corrosion. A heat exchanger leakage test should be conducted.
- ON. Verify both the limit control and the fan control are operating properly. Limit control operation can be checked by blocking the circulating air inlet or temporarily disconnecting the electrical supply to the blower motor and determining that the limit control acts to shut off the main burner gas.
- ON. Verify that the blower compartment door is properly installed and can be properly resecured if opened. Verify that the blower compartment door safety switch operates properly.
- ON. Check for flame disturbance before and after blower comes on which can indicate heat exchanger leaks.
- ON. Measure the CO in the vent after 5 minutes of main burner operation. The CO should not exceed threshold in Table D.6.
- OFF and ON. Inspect for evidence of water leaks around boiler and connected piping.
- ON. Verify that the water pumps are in operating condition. Test low water cutoffs, automatic feed controls, pressure and temperature limit controls, and relief valves in accordance with the manufacturer's recommendations to determine that they are in operating condition.
- ON. Measure the CO in the vent after 5 minutes of main burner operation. The CO should not exceed threshold in Table D.6.
- OFF. Verify that the pressure-temperature relief valve is in operating condition. Water in the heater should be at operating temperature.
- OFF. Verify that inspection covers, glass, and gaskets are intact and in place on a flammable vapor ignition resistant (FVIR) type water heater.
- ON. Verify that the thermostat is set in accordance with the manufacturer's operating instructions and measure the water temperature at the closest tub or sink to verify that it is not greater than 120°F.
- OFF. Where required by the local building code in earthquake prone locations, inspect that the water heater is secured to the wall studs in two locations (high and low) using appropriate metal strapping and bolts.
- OFF. Inspect oven cavity and range-top exhaust vent for blockage with aluminum foil or other materials.
- OFF. Inspect cook top to verify that it is free from a build-up of grease.
- ON. Measure the CO above each burner and at the oven exhaust vents after 5 minutes of burner operation. The CO should not exceed threshold in Table D.6.
- OFF. For built-in room heaters and wall furnaces, inspect that the burner compartment is free of lint and debris.
- OFF. Inspect that furnishings and combustible building components are not blocking the heater.
- OFF. Verify that the heater input is not more than 40,000 Btu input, but not more than 10,000 Btu where installed in a bedroom, and 6,000 Btu where installed in a bathroom.
- OFF. Inspect the ceramic logs provided with gas log type vent free heaters that they are properly located and aligned.
- OFF. Inspect the heater that it is free of excess lint build-up and debris.
- OFF. Verify that the oxygen depletion safety shutoff system has not been altered or bypassed.
- ON. Verify that the main burner shuts down within 3 minutes by extinguishing the pilot light. The test is meant to simulate the operation of the oxygen depletion system (ODS).
- ON. Measure the CO after 5 minutes of main burner operation. The CO should not exceed threshold in Table D.6.
- OFF. For gas logs installed in wood burning fireplaces equipped with a damper, verify that the fireplace damper is in a fixed open position.
- ON. Measure the CO in the firebox (log sets installed in wood burning fireplaces or in the vent (gas fireplace) after 5 minutes of main burner operation. The CO should not exceed threshold in Table D.6.
- OFF. Where installed in a closet, verify that a source of make-up air is provided and inspect that any make-up air openings, louvers, and ducts are free of blockage.
- OFF. Inspect for excess amounts of lint around the dryer and on dryer components. Inspect that there is a lint trap properly installed and it does not have holes or tears. Verify that it is in a clean condition.
- OFF. Inspect visible portions of the exhaust duct and connections for loose fittings and connections, blockage, and signs of corrosion. Verify that the duct termination is not blocked and that it terminates in an outdoor location. Verify that only approved metal vent ducting material is installed (plastic and vinyl materials are not approved for gas dryers).
- ON. Verify mechanical components including drum and blower are operating properly.
- ON. Operate the clothes dryer and verify that exhaust system is intact and exhaust is exiting the termination.
- ON. Measure the CO at the exhaust duct or termination after 5 minutes of main burner operation. The CO should not exceed threshold in Table D.6.
|Boilers (all categories)||400 ppm air free|
|Central Furnace (all categories)||400 ppm1 air free2, 3|
|Floor Furnace||400 ppm air free|
|Gravity Furnace||400 ppm air free|
|Wall Furnace (BIV)||200 ppm air free|
|Wall Furnace (Direct Vent)||400 ppm air free|
|Vented Room Heater||200 ppm air free|
|Vent-Free Room Heater||200 ppm air free|
|Water Heater||200 ppm air free|
|Oven/Broiler||225 ppm as measured|
|Top Burner||25 ppm as measured (per burner)|
|Clothes Dryer||400 ppm air free|
|Refrigerator||25 ppm as measured|
|Gas Log (gas fireplace)||25 ppm as measured in vent|
|Gas Log (installed in wood |
|400 ppm air free in firebox|
- Parts per million