Lennox MPGA 050 B3, Application Manual

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4. All pipe should be supported using the proper clamps
and/or straps. These supports should be at least
every four (4') feet.
5. All horizontal runs of pipe should have at least a 1/4"
(in.) per foot of upward slope from the furnace to the
vent terminal.
6. All runs of pipe should be as short as possible with
as few turns as possible.
7. Seams should be tightly joined and checked for
leaks.
8. The flue pipe must not extend into the chimney but
be flush with the inside wall.
9. The chimney or vent pipe must extend at least three
(3') feet above the highest point where it passes
through a roof of a building and at least two (2') feet
higher than any portion of a building within a
horizontal distance of ten (10') feet. It shall also
extend at least five (5') feet above highest connected
equipment flue collar.
Figure 9
VENT EXIT OPTIONS
10. The 3" to 4" vent adaptor coupling must be used to
connect to the combustion blower outlet. It must be
installed directly to the combustion blower outlet (See
Figure 8).
To Convert to Side Flue Exit:
1. Remove the louver door from the furnace. (Be sure
the side vent exit knock-out is removed from the right
side panel of the cabinet. See Figure 9.)
2. Disconnect the pressure switch tubing from the
combustion blower.
3. Remove the four (4) screws that secure the
combustion blower adaptor plate to the flue collector
box, taking care to support the blower assembly so
that it does not fall.
4. Rotate the blower 90° (degrees) clockwise, so that
the outlet of the blower is pointing toward the right
side panel of the furnace.
5. Insure that the gasket is in place between the blower
adaptor plate and the flue collector box. Reattach the
blower assembly to the flue collector box, using the
four (4) screws removed in step 3. Be sure that the
screws are properly tightened and that the gasket
seals the plate to the box.
6. Reconnect the pressure switch tubing to the
combustion blower.
7. (Optional) Install vent pipe guard.
Kit Number 20284801.
Figure 10
VENT PIPE GUARD KIT
For Horizontal Positions:
It is not necessary to reposition any of the
components of the furnace in order to install it in either
horizontal position. As outlined above, it is permissible to
use the side vent exit for the horizontal-left position, if
desired.
Checking For Vent Oversizing:
If this furnace is replacing a furnace that is attached
to a venting system serving other appliances, the venting
system is likely to be too large to properly vent all of the
attached appliances. An improperly sized venting system
can lead to condensation, leakage, or spillage.
20541501 Issue 0240 Page 14 of 26