Lennox G43UF SERIES Unit Information page 25

Follow the next three steps when installing the unit in Non-
Direct Vent applications where combustion air is taken
from indoors and flue gases are discharged outdoors.
1 − Use field−provided materials and the factory−provided
air intake screen to route the intake piping as shown in
figure 22. Maintain a minimum clearance of 3" (76mm)
around the air intake opening. The air intake opening
(with the protective screen) should always be directed
either downward or straight out. Use 2" pipe and fit-
tings only and make sure that the air intake does not
extend more than 6" beyond the G43UF cabinet.
The air intake connector must not be located near
the floor.
2 − Use a sheet metal screw to secure the intake pipe to the
connector, if desired. A pilot indentation is provided in the
slip connector to assist in locating and starting the fasten-
er.
3 − Glue the provided 2" plug into the unused air intake con-
nector on the opposite side of the cabinet.
Testing for Proper Venting and Sufficient Combustion Air
(Non−Direct Vent Applications Only)
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 G43UF gas furnace has been started, the follow-
ing test should be conducted to ensure proper venting and
sufficient combustion air has been provided to the G43UF,
as well as to other gas-fired appliances which are separate-
ly vented. The test should be conducted while all ap-
pliances (both in operation and those not in operation) are
connected to the venting system being tested. If the vent-
ing 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 lo-
cated 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 − Test for spillage of flue gases at the draft hood relief
opening after 5 minutes of main burner operation. Use
the flame of match or candle, or smoke from a ciga-
rette, cigar.
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 ANSI−Z223.1/NPFA 54
in the U.S.A., and the appropriate Natural Gas and
Propane appliances venting sizing tables in the cur-
rent standard of the CSA−B149 Natural Gas and Pro-
pane Installation Codes in Canada.
9 − After determining that each appliance remaining
connected to the common venting system properly
vents when tested as indicated in step 3, return
doors, windows, exhaust fans, fireplace dampers
and any other gas-burning appliance to their previous
condition of use.
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