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If the venting 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.
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.
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 G61MPVT is then classified as a non-direct
vent gas furnace. In Non-Direct Vent applications, the
vent termination is limited by local building codes.
Position termination end according to location given in fig-
ure 21. 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 305mm (12 inches) from any opening through which
flue products could enter the building.
At vent termination, care must be taken to maintain
protective coatings over building materials (prolonged
exposure to exhaust condensate can destroy protective
coatings). It is recommended that the exhaust outlet not be
located within 1.8m (6 feet) of a condensing unit because
the condensate can damage the painted coating.
NOTE − If winter design temperature is below 0°C (32°F),
exhaust piping should be insulated with 13mm (1/2 inch),
Armaflex or equivalent when run through unheated space.
Do not leave any surface area of exhaust pipe open to out-
side air; exterior exhaust pipe should be insulated with
13mm (1/2 inch) Armaflex or equivalent. In extreme cold
climate areas, 19mm (3/4 inch) Armaflex or equivalent may
be necessary. Insulation on outside runs of exhaust pipe
must be painted or wrapped to protect insulation from dete-
rioration. Exhaust pipe insulation may not be necessary in
some specific applications.
NOTE − During extremely cold temperatures, below
approximately −6.7°C (20°F), units with long runs of vent
pipe through unconditioned space, even when insulated,
may form ice in the exhaust termination that prevents the
unit from operating properly. Longer run times of at least 5
minutes will alleviate most icing problems. Also, a heating
cable may be installed on exhaust piping and termination to
prevent freeze−ups. Heating cable installation kit is avail-
able from Lennox.
