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1 -    In areas where piping penetrates joists or interior 
walls, hole must be large enough to allow clearance 
on all sides of pipe through center of hole using a 
hanger.
2 -  When furnace is installed in a residence where unit 
is shut down for an extended period of time, such 
as a vacation home, make provisions for draining 
condensate collection trap and lines.
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  deciencies 
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  replace 
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  ue  gases  at  the  draft  hood  relief 
opening. Use the ame of a match or candle.
6 -  After determining that each appliance connected to 
the common venting system is venting properly, (step 
3)  return  all doors,  widows,  exhaust  fans,  replace 
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  modied  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 standards of 
the National Fuel Gas Code ANSI Z223.1.
Exhaust Piping (FIGURE 26 and FIGURE 27)
Route piping to outside of structure. Continue with instal-
lation following instructions given in piping termination 
section.
 WARNING
Carbon Monoxide Poisoning Hazard
Cutting or altering exhaust or air intake pipes, which 
are located in the blower compartment, could result in 
Carbon Monoxide Poisoning or Death.
 CAUTION
Do not discharge exhaust into an existing stack or 
stack that also serves another gas appliance. If vertical 
discharge through an existing unused stack is required, 
insert PVC pipe inside the stack until the end is even 
with the top or outlet end of the metal stack.
 CAUTION
The exhaust vent pipe operates under positive pressure 
and must be completely sealed to prevent leakage of 
combustion products into the living space.