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Heatilator • GDST4336IFT, GDFL4136IFT Installation Manual • 2480-980 Rev. B • 3/17
MEASURE TO SHADED SURFACE
(OUTSIDE MOUNTING SURFACE)
Figure 4.6 Measure to Outside Mounting Surface
Figure 4.7. Measure to Top of Last Section of Pipe
General Rules:
• SUBTRACT 3 ft. from the total H measurement for each
90º elbow installed horizontally.
• SUBTRACT 1-1/2 ft. from the total H measurement for
each 45º elbow installed horizontally.
• A maximum of three 90º elbows (or six 45º elbows) may
be used in any vent con
fi
guration. Some elbows may be
installed horizontally.
• Elbows may be placed back to back anywhere in the
system.
•
Any 90º elbow may be replaced with two back to back
45º elbows.
• When penetrating a combustible wall, a wall shield
fi
restop must be installed.
• When penetrating a combustible ceiling, a ceiling
fi
restop
must be installed.
• Horizontal runs of vent do not require vertical rise;
horizontal runs may be level.
• Horizontal termination cap should have a 1/4 inch
downward slant to allow any moisture in cap to be
released. See Figure 4.8.
F. Vent Diagrams
Top Vent
Horizontal Termination
Two 45° Elbows
Installation requirements to replace the
fi
rst 90° elbow
with two 45° elbows:
4 ft min.
(1.22 m)
16 ft max.
(4.87 m)
1/4 in. max.
(6 mm)
Figure 4.8
Note:
Reference Figure 4.21 for
special instructions for use of 45º
elbow on rear vent appliances.
To replace the
fi
rst starter elbow with two 45° elbows,
refer to Figure 4.8. All other 90° elbows can be replaced
with two 45° elbows.
E. Measuring Standards
Vertical and horizontal measurements listed in the vent
diagrams were made using the following standards:
• Pipe measurements are shown using the effective length
of pipe. See Section 12.A (Figure 12.1 for DVP, Figure
12.8 for SLP) for information on effective length of pipe
components.
• Horizontal terminations are measured to the outside
mounting surface (
fl
ange of termination cap) (see Figure
4.6).
• Vertical terminations are measured to top of last section
of pipe. See Figure 4.7.
• Horizontal pipe installed level with no rise.