Venting installation – Desa (V)3612ST User Manual
Page 7

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115603-01C
7
Figure 14 - Pipe Connection
LINEAL GAIN
PART NO.
DESCRIPTION
GAIN
V3612ST
See-Through
Fireplace
52
3
/
4
"
48-12DM
48-12TM
Flue Pipe
46
5
/
8
"
36-12DM
48-12TM
Flue Pipe
34
5
/
8
"
24-12DM
48-12TM
Flue Pipe
22
5
/
8
"
18-12DM
48-12TM
Flue Pipe
16
5
/
8
"
12-12DM
48-12TM
Flue Pipe
10
5
/
8
"
STL-12D
Chase Style
Termination
1" to 12"
RTL-12D
Round Top
Termination
7"
Hemmed 
End
12 3/8" 
Stainless 
Inner Pipe
15" Galvanized 
Outer Pipe
PIPE INSTALLATION
The pipe sections must be assembled inde-
pendently as the chimney is installed. When 
connecting chimney directly to the fireplace, 
the inner flue pipe section must be installed first 
with the lanced side up. The outer pipe section 
can then be installed over the flue pipe section 
with the hemmed end up. Press down on each 
pipe section until the lances securely engage 
the hem on the fireplace starter. The wire will 
assure the proper spacing between the inner 
and outer pipe sections.
Continue to assemble chimney sections as 
outlined above, making sure that both the 
inner and outer pipe sections are locked to-
gether. When installing double wall snap-lock 
chimney together, it is important to assure the 
joint between the chimney sections is locked. 
Check by pulling chimney upward after lock-
ing. The chimney will not come apart if prop-
erly locked. It is not necessary to add screws 
to keep the chimney together (exception, see 
Figure 17, page 8).
WARNING: The opening in the
collar around the chimney at the
top of the fireplace must not be
obstructed. Never use blown insula-
tion to fill the chimney enclosure.
Figure 13 - Outside Air Kit Installation
Secure to Collars with 
Duct Tape or Screws
Air Inlet 
Location 
Must Allow 
For Bushes 
or Snow
Vent Hood 
Required for 
Wall Installation
Air Inlet 
Termination
Vented Crawl Space
(Check Local Codes 
Before Installing in a 
Vented Crawl Space)
CHIMNEY PIPE
The DESA chimney is a snap-lock, double-
wall pipe. It consists of a stainless steel inner 
flue pipe(s), a galvanized outer pipe and a 
wire spacer.
Each section of pipe comes in lengths of 12", 
18" 36" and 48". The actual lineal gain for 
each is measured after each section is fully 
connected. Lineal gain is the actual measur-
able length of a part after two or more parts 
are connected. 
VenTing inSTallaTion
Continued
USING ELBOW OFFSETS AND 
SUPPORTS
Chimney weight above offset rests on return 
elbow. Straps must be securely nailed to raf-
ters or joists (see Figure 15, page 8).
To achieve desired offset, you may install 
combinations of 12", 18", 36" and 48" length 
of double wall pipe (see offset chart and 
Figure 16, page 8).
The chimney support section is a 4" strap 
and 12" length of pipe. A chimney support is 
required every 30 feet above fireplace after a 
straight chimney run or above a return elbow 
after a straight chimney run (see Figure 17, 
page 8). This support is designed to relieve 
the extra weight load on fireplace and elbows 
when high chimneys are installed.
