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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 furnace has been started, the following test
should be conducted to ensure proper venting and suffi-
cient combustion air has been provided to the furnace, as
well as to other gas-fired appliances which are separately
vented. The test should be conducted while all appliances
(both in operation and those not in operation) are con-
nected to the venting system being tested.
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 stan-
dards of the National Fuel Gas Code
ANSI−Z223.1/NPFA 54 in the U.S.A., and the ap-
propriate Natural Gas and Propane appliances vent-
ing sizing tables in the current standard of the
CSA−B149.1 Natural Gas and Propane Installation
Code 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 pre-
vious condition of use.
General Guidelines for Vent Terminations for Non-Direct
Vent Installations.
In Non-Direct Vent applications, combustion air is taken
from indoors and the flue gases are discharged to the out-
doors. The furnace is then classified as a non-direct vent,
Category IV gas furnace. In Non-Direct Vent applications,
the vent termination is limited by local building codes. In
the absence of local codes, refer to the current National
Fuel Gas Code ANSI Z223−1/NFPA 54 in U.S.A., and cur-
rent standards CSA−B149.1 of the Natural Gas and Pro-
pane Installation Codes in Canada for details.
Position termination end according to location given in fig-
ure 11. In addition, position termination end so it is free
from any obstructions and above the level of snow accu-
mulation (where applicable). The termination should be at
least 12 inches (305mm) from any opening through which
flue products could enter the building.