Lennox International Inc G61MP Series Units, Gas Units General Guidelines for Vent Terminations

General Guidelines for Vent Terminations

In Non-Direct Vent applications, combustion air is taken from indoors and the flue gases are discharged to the out- doors. The G61MP is then classified as a non-direct vent, Category IV gas furnace.

In Direct Vent applications, combustion air is taken from outdoors and the flue gases are discharged to the out- doors. The G61MP is then classified as a direct vent, Category IV gas furnace.

In both Non-Direct Vent and 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 current CSA−B149 Natural Gas and Propane Installation Codes in Canada for details.

Position termination according to location given in figure 29 or 30. In addition, position termination so it is free from any obstructions and 12" above the average snow accumula- tion.

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 6 feet (1.8m) of a condensing unit because the condensate can damage the painted coating.

NOTE − If winter design temperature is below 32°F (0°C), exhaust piping should be insulated with 1/2" (13mm), Ar- maflex 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 1/2"

(13mm) Armaflex or equivalent. In extreme cold climate areas, 3/4" (19mm) Armaflex or equivalent may be neces- sary. Insulation on outside runs of exhaust pipe must be painted or wrapped to protect insulation from deterioration. Exhaust pipe insulation may not be necessary in some specific applications.

NOTE − During extremely cold temperatures, below approximately 20°F (6.7°C), 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. See Condensate Piping section for part numbers.

IMPORTANT

Do not use screens or perforated metal in exhaust terminations. Doing so will cause freeze−ups and may block the terminations.

IMPORTANT

For Canadian Installations Only:

In accordance to CSA International B149 installation codes, the minimum allowed distance between the combustion air intake inlet and the exhaust outlet of other appliances shall not be less than 12 inches (305mm).

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