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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 applianc-
es, the venting system is likely to be too large to properly
vent the remaining attached appliances. Conduct the fol-
lowing test while each appliance is operating and the oth-
er appliances (which are not operating) remain 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 requirements 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 monoxide poisoning
or death. The following steps shall be followed for each
appliance 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
system.
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 between the space in which the appliances
remaining connected to the common venting system
are located and other spaces of the building. Turn on
clothes dryers 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 operate at maximum speed. Do not
operate a summer exhaust 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
dampers, and any other gas-burning appliances to
their previous mode of operation.
7 - If a venting problem is found during any of the
preceding tests, the common venting system must
be modified 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
Gas supply piping should not allow more than 0.5"W.C.
drop in pressure between gas meter and unit. Supply gas
pipe must not be smaller than unit gas connection.
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.
Do not over torque (800 in-lbs) or under torque (350 in-
lbs) when attaching the gas piping to the gas valve.
1 - This unit is shipped standard for left or right side instal-
lation of gas piping. Connect the gas supply piping into
the gas valve. The maximum torque is 800 in lbs and min-
imum torque is 350 in lbs when attaching the gas piping
to the gas valve.
2 - When connecting the gas supply piping, consider fac-
tors such as length of run, number of fittings, and furnace
rating to avoid excessive pressure drop. Table 8 lists rec-
ommended 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 furnace.
The piping must be supported at proper intervals [every 8
to 10 feet (2.44 to 3.01 m)] with suitable hangers 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
figure 23.
6 - In some localities, codes may require the installation
of a manual main shut-off valve and union (furnished by
the installer) external to the unit. The union must be of the
ground joint type.
Compounds used on threaded joints of gas piping must
be resistant to the actions of liquefied petroleum gases.
NOTE - If emergency shutoff is necessary, shut off the
main manual gas valve and disconnect main power to the
furnace. The installer should properly label these devices.
Page 17
CAUTION
WARNING
CAUTION
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