Vermont Castings • Dauntless FlexBurn Installation Manual_R8 • 2020 - ___ • 11/21
16
3-90-586000i
Thimble
Site constructed for masonry chimney installation:
Components
•
A minimum length of 12” (305 mm) (longer for thicker
walls) of solid insulated factory-built chimney length
constructed to UL 103 Type HT 6” (152 mm) inside
diameter. Chimney needs to extend a minimum of 2” (51
mm) from the interior wall and a minimum of 1” (25 mm)
from the exterior wall.
•
Wall spacer, trim collar and wall band to fit solid pack
chimney selected.
•
Minimum 8” (203 mm) diameter clay liner section (if not
already present in chimney) and refractory mortar.
• When jurisdiction requires install approved chimney liner
in masonry chimney.
Air Clearances
• Masonry chimney clearance must meet NFPA 211
minimum requirement of 2” (51 mm) to sheet metal
supports and combustibles.
• Minimum of 1” (25 mm) clearance around the chimney
connector.
• Top of wall opening is a minimum of 13-1/2” (343 mm)
from ceiling or 4-1/2” (114 mm) below minimum clearance
specified by chimney connector manufacturer. NFPA 211
minimum vertical clearance of 18” (457mm) from chimney
connector and ceiling or minimum recommended by
chimney connector manufacturer, Figure 4.3
Instructions
1. Open inside wall at proper height for the chimney
connector to enter the masonry chimney, Figure 4.3
2. Entry hole to masonry chimney must be lined with an 8”
(203 mm) minimum diameter clay liner, or equivalent,
secured with refractory mortar.
3. Construct a 17” x 17” (432 mm x 432 mm) outside
dimension frame from 2 x 2 framing lumber to fit into
wall opening. Inside opening of frame should be no less
than 14” x 14” (356 mm x 356 mm), Figure 4.4.
Attach the wall spacer to the chimney side of the frame.
5. Nail the frame into the wall opening. The spacer should
be on the chimney side.
6. Insert the section of the solid insulated chimney into the
outer wall of the masonry chimney.
7. Tightly secure the length of the solid insulated chimney
with the wall band to the masonry chimney.
8. Insert a section of chimney connector into the chimney.
Make sure it does not protrude past the edge of the clay
chimney liner inside the chimney.
9. Seal the end of the chimney connector to the clay liner
with refractory mortar.
10.
Install trim collar around the sold pack chimney section
.
Figure 4.3
1.5”
1.0”
2.0”
2.0”
1.5”
14.0” ID
17.0” OD
ceiling
Minimum18.0”
NFPA 211
13.5” below ceiling to top
of opening
1.0”
8.0”
1.5 2x2 framing stud
2.0 min air clearance
1.0 min air clearance
4.5
or top of opening is a min.of
4.5” below min.clearance
specified by connector mfg.
Center of Hole
Thimble
CL
CL
Wall
Include depth
of hearth pad
Solid Pack Chimney with Metal Supports as a Thimble
Trim Collar
Chimney Section
with 2 inch (51 mm)
Clearance to
Combustibles
Chimney
Connector
Fire Clay Flue Liner
with Airspace
Masonry
Chimney
Wall Band to
Secure Chimney
Section
Wood Studs Used for
Framing - Spaced 2
inch (51 mm) clearance
from Masonry Chimney
Wall Spacer
Figure 4.4
1 inch (35 mm) Air Space
to Chimney Section
Min. Clearance
2 inch (51 mm)
Min. Chimney Clearance to Wall Spacer
and Combustible - 2 inch (51 mm)
Chimney
Flue Liner
Fireclay Liner
or Equivalent
Masonry Chimney
Constructed to NFPA 211
Wall Spacer
Wall Band
Trim Collar
Chimney Section
Chimney
Connector
Figure 4.5
