Installation
900683-01F, 10/2018
Innovative Hearth Products
DRT3500 Series Direct-Vent Gas Fireplaces
29
Table 17 - Top Vent—Two 90° Elbows
H Maximum
V Minimum
feet
meters
feet
meters
5
1.524
Elbow Only
5
1.524
1
0.305
10
3.048
2
0.610
15
4.572
3
0.914
25
7.62
5
1.524
Ceiling firestop/
spacer SV4.5VF *
Wall firestop/
spacer SV4.5HF **
When using Secure Flex
®
, use
ceiling firestop/spacer SF4.5VF.
When using Secure Flex, use
wall firestop/spacer SF4.5HF.
*
**
V1
H
V
V + V
1
+ H = 60 ft (18.3 m) maximum
H = 25 ft (7.62 m) maximum
Install the U-shaped vent restrictor in any vent run
with more than 6 ft of vertical rise. See Page 22 for
more information.
If 25 ft of (H) horizontal vent run is needed,
then 5 ft (straight section) minimum of (V)
vertical vent will be required.
This table shows a 1 (V) to 5 (H) ratio. For
every 1 ft of (V) vertical, you are allowed 5
ft of (H) horizontal run, up to a maximum
horizontal run of 25 ft.
Minimum 6 ft and maximum of 60 ft of
vertical venting.
Table 18 - Rear Vent—Three Elbows
H + H
1
Maximum
H Maximum
V Minimum
ft
m
ft
m
ft
m
5
1.524
2
0.610
1
0.305
10
3.048
4
1.219
2
0.610
15
4.572
6
1.829
3
0.914
20
6.096
8
2.438
4
1.219
V
V
Ceiling
firestop/spacer
SV4.5VF *
Wall firestop/
spacer
SV4.5HF **
When using
Secure Flex
®
, use
ceiling firestop/
spacer SF4.5VF.
When using
Secure Flex, use
wall firestop/
spacer SF4.5HF.
*
**
V1
H
Ceiling
firestop/spacer
SV4.5VF *
H1
H = 8 ft (2.4 m) maximum
H + H1 = 20 ft (6.1 m) maximum
V + V1 + H + H1 = 60 ft (18.3 m) maximum
Install the U-shaped vent restrictor in any vent run
with more than 6 ft of vertical rise. See Page 22 for
more information.
If 20 ft of (H) horizontal vent run is needed,
then 4 ft (straight section) minimum of (V)
vertical vent will be required.
This table shows a 1 (V) to 5 (H) ratio. For
every 1 ft of (V) vertical, you are allowed 5
ft of (H) horizontal run, up to a maximum
horizontal run of 20 ft.
NOTE: The vent system may have a
maximum of three (3) 90° elbows.
Minimum 6 ft of vertical venting.
Table 19 - Top Vent—Three Elbows
H + H
1
Maximum
V Minimum
feet
meters
feet
meters
5
1.524
Elbow Only
5
1.524
1
0.305
10
3.048
2
0.610
15
4.572
3
0.914
20
6.096
4
1.219
Ceiling firestop/
spacer SV4.5VF
*
Wall firestop/
spacer
SV4.5HF **
When using Secure Flex
®
, use
ceiling firestop/spacer SF4.5VF.
When using Secure Flex, use
wall firestop/spacer SF4.5HF.
*
**
V1
H
V
H1
H + H1 = 20 ft (6.1 m) maximum
V + V1 + H + H1 = 60 ft (18.3 m) maximum
Install the U-shaped vent restrictor in any vent
run with more than 6 ft of vertical rise. See Page
22 for more information.
If 20 ft of (H) horizontal vent run is
needed, then 4 ft (straight section)
minimum of (V) vertical vent will be
required.
This table shows a 1 (V) to 5 (H) ratio.
For every 1 ft of (V) vertical, you are
allowed 5 ft of (H) horizontal run, up to
a maximum horizontal run of 20 ft.
NOTE: The vent system may have a
maximum of three (3) 90° elbows.
Minimum 6 ft and maximum of 60 ft of
vertical venting.
