
Installation
Greenstar FS/Combi FS – 6 720 810 590 (2020/04)
46
6.9.3
Vent and combustion pipe lengths
With Flex pipe the maximum length is reduced by 50% Flex pipe
according to the suppliers instructions for use in the vertical part of the
installation only.
3” (76mm) Vent and combustion air pipe
For all installation situations and for all appliances the maximum vent
and combustion air pipe length is 100 feet each, with no more than 8
elbows each.
2” (50mm) Vent and combustion air pipo
The maximum combined vent and combustion air pipe length (
tab.
21, 22 and 23) depend on the installation situation, the appliance type
and the number of elbows used.
Flue runs must be one continuous diameter and the exhaust and inlet
pipe must be of the same diameter.
Any pipe diameter reductions must be made at the supplied adaptor or
within 1 foot of the adaptor
Table 21 Vent and combustion air pipe lengths with 2" diameter and the
stainless steel wall termination
Table 22 Vent and combustion air pipe lengths with 2" diameter and
separate terminations
Table 23 Vent and combustion air pipe lengths with 2" diameter and the
concentric termination
Ø 3” / Ø 5” (Ø 80/125mm) Concentric venting system
The maximum concentric pipe length (
Tab. 25) depends on the
installation situation, the appliance type and the number of elbows used.
Table 24 Pipe lengths with Ø 3" / Ø 5" (Ø 80/125 mm) diameter and
termination
Table 25 Concentric pipe friction loss equivalent for fittings
Example:
• Model
KBR 28-3A
• 90° elbow used - 2
• 45° elbow used - 2
Maximum straight vent pipe allowed =
38ft (11.6m)
Installations
Fig. 32, 33, 34, 36, 37and 39
Separate terminations
2” PIPE
Maximum effective vent pipe length
allowed for Ø 2” pipe
KBR 16-3
KBR 35-3
KBR 21-3
KWB 35-3
Number of 90°
KBR 28-3
KBR 42-3
elbows used
KWB 28-3
KWB 42-3
1
81ft (24.6m)
65ft (19.8m)
2
76ft (23.1m)
57ft (17.3m)
3
71ft (21.6m)
48ft (14.6m)
4
66ft (20.1m)
40ft (12.2m)
5
61ft (18.6m)
32ft (9.8m)
6
56ft (17.1m)
23ft (7.0m)
Installations
Fig. 35, Stainless steel wall terminations
2” PIPE
Maximum effective vent pipe length
allowed for Ø 2” pipe
KBR 16-3
KBR 35-3
KBR 21-3
KWB 35-3
Number of 90°
KBR 28-3
KBR 42-3
elbows used
KWB 28-3
KWB 42-3
1
76ft (23.1m)
60ft (18.3m)
2
71ft (21.6m)
52ft (15.9m)
3
66ft (20.1m)
43ft (13.1m)
4
61ft (18.6m)
35ft (10.7m)
5
56ft (17.1m)
27ft (8.2m)
6
51ft (15.6m)
18ft (5.5m)
Installations
Fig. 38, Concentric terminations
2” PIPE
Maximum effective vent pipe length
allowed for Ø 2” pipe
KBR 16-3
KBR 35-3
KBR 21-3
KWB 35-3
Number of 90°
KBR 28-3
KBR 42-3
elbows used
KWB 28-3
KWB 42-3
1
66ft (20.1m)
47ft (14.3m)
2
61ft (18.6m)
38ft (11.6m)
3
56ft (17.1m)
30ft (9.1m)
4
51ft (15.6m)
22ft (6.7m)
5
46ft (14.1m)
13ft (4.0m)
6
41ft (12.5m)
5ft (1.5m)
Installations
Ø 3” / Ø 5” (Ø 80 / 125mm)
CONCENTRIC
PIPE
Max. straight vent pipe length allowed for
Ø 3” / Ø 5” (Ø 80 / 125mm) concentric pipe
KBR 16-3
KBR 35-3
KBR 21-3
KWB 35-3
Number of 90°
KBR 28-3
KBR 42-3
elbows used
KWB 28-3
KWB 42-3
1
50ft (15.2m)
44ft (13.4m)
2
44ft (13.4m)
38ft (11.6m)
3
38ft (11.6m)
32ft (9.8m)
4
32ft (9.8m)
26ft (7.9m)
5
26ft (7.9m)
20ft (6.1m)
6
20ft (6.1m)
14ft (4.3m)
Fitting
Equivalent
ft
m
45° elbow
3
0.91
90° elbow
6
1.82