Testing for Proper Venting and Sufficient Combustion Air for
WARNING
CARBON MONOXIDE POISONING HAZARD!
Failure to follow the steps outlined below for each appliance connected to the venting system being placed into operation could result in carbon monox ide poisoning or death.
The following steps shall be followed for each ap pliance connected to the venting system being placed into operation, while all other appliances con nected to the venting system are not in operation.
After the ML193UH gas furnace has been started, the fol lowing test should be conducted to ensure proper venting and sufficient combustion air has been provided to the ML193UH as well as to other gas‐fired appliances which are separately vented.
If a ML193UH furnace replaces a Category I furnace which was commonly vented with another gas appliance, the size of the existing vent pipe for that gas appliance must be checked. Without the heat of the original furnace flue prod ucts, the existing vent pipe is probably oversized for the single water heater or other appliance. The vent should be checked for proper draw with the remaining appliance.
The test should be conducted while all appliances (both in operation and those not in operation) are connected to the venting system being tested. If the venting system has been installed improperly, or if provisions have not been made for sufficient amounts of combustion air, corrections must be made as outlined in the previous section.
1 - Seal any unused openings in the venting system.
2 - Visually inspect the venting system for proper size and
horizontal pitch. Determine there is no blockage or re striction, leakage, corrosion, or other deficiencies which could cause an unsafe condition.
3 - To the extent that it is practical, close all building doors and windows and all doors between the space in which the appliances connected to the venting system are located and other spaces of the building.
4 - Close fireplace dampers.
5 - Turn on clothes dryers and any appliances not con nected to the venting system. 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.
6 - Follow the lighting instruction to place the appliance being inspected into operation. Adjust thermostat so appliance will operate continuously.
7 - Use the flame of match or candle to test for spillage of flue gases at the draft hood relief opening after 5 min utes of main burner operation.
8 - If improper venting is observed during any of the above tests, the venting system must be corrected or sufficient combustion/make‐up air must be provided. The venting system should be re‐sized to approach the minimum size as determined by using the ap propriate tables in appendix G in the current standards of the National Fuel Gas Code
9 - After determining that each appliance remaining con nected to the common venting system properly vents when tested as indicated in step 3, return doors, win dows, exhaust fans, fireplace dampers and any other gas‐burning appliance to their previous condition of use.
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