Removal of the Furnace from Common Vent
In the event that an existing furnace is removed from a venting system commonly run with separate gas ap- pliances, the venting system is likely to be too large to properly vent the remaining attached appliances.
Conduct the following test while each appliance is operat- ing and the other appliances (which are not operating) re- main connected to the common venting system. If the venting system has been installed improperly, you must correct the system as indicated in the general venting re- quirements section.
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 mon- oxide 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 connected to the venting system are not in operation:
1 − Seal any unused openings in the common venting sys- tem.
2 − Inspect the venting system for proper size and horizontal pitch. Determine that there is no blockage, restriction, leakage, corrosion, or other deficiencies which could cause an unsafe condition.
3 − Close all building doors and windows and all doors be- tween the space in which the appliances remaining connected to the common venting system are located and other spaces of the building. Turn on clothes dry- ers and any appliances not connected to the common venting system. Turn on any exhaust fans, such as range hoods and bathroom exhausts, so they will oper- ate at maximum speed. Do not operate a summer ex- haust fan. Close fireplace dampers.
4 − Follow the lighting instructions. Turn on the appliance that is being inspected. Adjust the thermostat so that the appliance operates continuously.
5 − After the main burner has operated for 5 minutes, test for leaks of flue gases at the draft hood relief opening. Use the flame of a match or candle, or smoke from a cigarette, cigar, or pipe.
6 − After determining that each appliance connected to the common venting system is venting properly, (step 3) return all doors, widows, exhaust fans, fireplace damp- ers, and any other gas−burning appliances to their pre- vious mode of operation.
7 − If a venting problem is found during any of the preced- ing tests, the common venting system must be modi- fied to correct the problem.
Resize the common venting system to the minimum vent pipe size determined by using the appropriate tables in Appendix G. (These are in the current stan- dards of the National Fuel Gas Code ANSI Z223.1.
Gas Piping
CAUTION
If a flexible gas connector is required or allowed by the authority that has jurisdiction, black iron pipe shall be installed at the gas valve and extend outside the furnace cabinet. The flexible connector can then be added between the black iron pipe and the gas supply line.
Gas Supply
1 − This unit is shipped standard for left or right side instal- lation of gas piping. Connect the gas supply to the pip- ing assembly.
2 − When connecting the gas supply piping, consider fac- tors such as length of run, number of fittings, and fur- nace rating to avoid excessive pressure drop. Table 11 lists recommended pipe sizes for typical applications.
3 − The gas piping must not run in or through air ducts, clothes chutes, gas vents or chimneys, dumb waiters, or elevator shafts.
4 − The piping should be sloped 1/4 inch (6.4 mm) per 15 feet (4.57 m) upward toward the meter from the fur- nace. The piping must be supported at proper intervals [every 8 to 10 feet (2.44 to 3.01 m)] with suitable hang- ers or straps. Install a drip leg inside vertical pipe runs to the unit.
5 − A 1/8" N.P.T. plugged tap or pressure post is located on the gas valve to facilitate test gauge connection. See figures 26 and 27.
6 − In some localities, codes may require the installation of a manual main
IMPORTANT
Compounds used on threaded joints of gas piping must be resistant to the actions of liquified petro- leum gases.
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