Appendix G Checking Draft and Combustion

APPENDIX G – CHECKING DRAFT AND COMBUSTION

CHECK DRAFT (GAS BOILERS WITH DRAFT HOODS)

1.Insofar as is practical, close all doors and windows in the building.

2.Turn on all appliances not connected to the same venting system as the boiler being checked.

3.Turn on all exhaust fans (such as range hoods and bathroom exhausts) to their maximum speed. Do not turn on any summer exhaust fans.

4.Close all fireplace dampers.

5.Operate the appliance being checked. Follow lighting instructions.

6.After 5 minutes of main burner operation, test for spillage at the draft hood relief opening, using a lighted match, candle, cigarette, etc.

7.Repeat this test for each appliance connected to the common venting system.

8.If any appliance does not vent properly, per the above test, make corrections, so that the installation conforms to the National Fuel Gas Code, NFPA 54/ANSI Z223.1, and/or Installation Codes, CAN/CSA B149.1.

9.Return doors, windows, exhaust fans, fireplace dampers, and any other gas- burning appliance to their previous condition of use.

CHECK DRAFT (OIL BOILERS)

1.Use a manometer precise to 0.01” water column.

2.Fire the boiler until the chimney/vent reaches normal operating temperature.

3.Locate the pressure sensing tapping on the boiler.

4.While the boiler is still firing, use the manometer to measure the draft at the pressure tapping.

5.Confirm that the draft measurement matches the required draft specified for the boiler.

6.If the required draft is not present, make any necessary adjustments and check again.

CHECK COMBUSTION

1.Use a flue gas analyzer that accurately

measures CO2, O2, CO, and flue gas temperature.

2.For oil boilers, also use a smoke tester with smoke test paper.

3.Operate the boiler at its rated (high fire) input.

4.With the analyzer, check the CO2 (or O2), CO and temperature of the flue gases exiting the boiler.

5.For two-stage or modulating boilers, also

check the CO2 (or O2), CO and temperature of the flue gases at low fire.

6.Confirm that the measured CO2 (or O2) matches the required CO2 (or O2) specified for the boiler.

7.For oil boilers, also take a smoke measurement of the flue gases. Smoke should not exceed #1.

If CO2, O2, or CO fall outside of the range specified for the boiler, review the

installation and startup instructions and make any necessary adjustments to the boiler or associated venting or piping systems.

Note the gross flue gas temperature for i future reference. Significant changes in

flue gas temperature can indicate changes in the boiler’s operating efficiency.