Filters; Duct System; Venting; Gas Piping - Lennox Merit Series Installation Instructions Manual

WARNING
!
The blower access panel must be securely
in place when the blower and burners are
operating. Gas fumes, which could contain
carbon monoxide, can be drawn into living
space resulting in personal injury or death.

FILTERS

This unit is not equipped with a filter or rack. A field-provided
high-velocity filter is required for the unit to operate properly.
Table 2 lists recommended filter sizes. A filter must be in
place any time the unit is operating.
TABLE 2
Furnace Filter Size mm (in) and quantity
Cabinet Width
Side Return
A - 338 406 X 635 X 25 1
(14-1/2") (16 X 25 X 1)
B- 446 406 X 635 X 25 1
(17-1/2") (16 X 25 X 1)
C - 533 405 X 635 X 25 1
( 21") (16 X 25 X 1)
D - 622 405 X 635 X 25 2
(24-1/2") (16 X 25 X 1)

DUCT SYSTEM

Use industry approved standards (such as those published
by Air Conditioning Contractors of America or American
Society of Heating, Refrigerating and Air Conditioning
Engineers) to size and install the supply and return air duct
system. This will result in a quiet and low static system that
has uniform air distribution.

VENTING

The Lennox Merit Series
™
furnace equipped with an integral mechanical means to
either draw or force products of combustion through the
combustion chamber and/or heat exchanger. When installed
in the vertical position and vented vertically, the furnace
operates with a non-positive vent stack pressure. When
installed in the horizontal position and vented vertically, the
furnace operates with a positive stack pressure.
Bottom Return
356 X 635 X 25 1
(14 X 25 X 1)
406 X 635 X 25 1
(16 X 25 X 1)
508 X 635 X 25 1
(20 X 25 X 1)
610 X 635 X 25 1
(24 X 25 X 1)
Gas Furnace is a fan-assisted

GAS PIPING

Refer to the current edition of the Australian Gas
Installation Code (AG601, ES5601) for gas piping
requirements and gas pipe sizing tables.
Gas supply piping should not allow more than 125 Pa
(0.5"W.C.) drop in pressure between gas meter and unit.
Supply gas pipe must not be smaller than unit gas
connection.
CAUTION
!
If a flexible gas connector is required or
allowed by the authority that has jurisdiction,
black iron pipe shall be installed at the gas
valve and extend outside the furnace cabinet.
The flexible connector can then be added
between the black iron pipe and the gas
supply line.
GAS SUPPLY
1. This unit is shipped standard for left or right side
installation of gas piping (or top entry in horizontal
applications). Connect the gas supply to the piping
assembly.
2. When connecting the gas supply piping, consider factors
such as length of run, number of fittings, and furnace
rating to avoid excessive pressure drop.
3. The gas piping must not run in or through air ducts,
clothes chutes, gas vents or chimneys, dumb waiters, or
elevator shafts.
4. The piping should be sloped 6.4mm (1/4 in) per 4.57m
(15 ft.) upward toward the meter from the furnace. The
piping must be supported at proper intervals every 2.44
to 3.01m (8 to 10ft) with suitable hangers or straps.
Install a drip leg in vertical pipe runs to the unit.
5. A 3 mm (1/8") N.P.T. plugged tap or pressure port is
located on the gas valve to facilitate test gauge connection.
6. In some localities, codes may require the installation of a
manual main shut off valve and union (furnished by the
installer) external to the unit. The union must be of the
ground joint type.
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