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An inner flue finishing kit [1] is provided which should be fitted to the
ducts before assembly.
▶ Push the assembly through the wall and slide the terminal onto the
flue connector. Ensure that the terminal is fully entered into the
socket on the boiler.
▶ From the outside fix the flue finishing kit to the terminal and, after
ensuring the flue is properly inclined towards the boiler, fix the
finishing kit to the wall. If the terminal is within 2 m of the ground
where there is access then an approved terminal guard must be
fitted. The guard must give a clearance of at least 50mm around the
terminal and be fixed with corrosion resistant screws.
3.9
Flue gas connection
3.9.1
Open flue operation
If room-sealed fluing is not desired or possible due to local conditions,
the boiler can be set up for operation to take air for combustion from the
room in an open flue arrangement (contact Worcester Technical team for
advice).
The boiler is factory-fitted with a concentric connection.
An air intake strainer basket can be used for open flue operation.
This prevents ingress from entering the boiler (contact Worcester
Technical; accessory).
3.9.2
Room sealed operation
The boiler can be connected to a concentric flue gas system.
The boiler is factory-fitted with a concentric connection.
3.9.3
Flue material
When using 3rd party plastic flue material, PPS is recommended.
3.9.4
Calculating the air intake and flue gas pipe dimensions
The total reduced pipe length is calculated from the sum of the reduced
length of the horizontal and vertical flue ducting and elbows
( table 11).
The total reduced flue length must be less than the maximum allowable
flue length ( table 10).
See also the next example.
All measurements in millimetres
3
300
1,500
2
1
300
1,500
1,200
Boundary Line
Fig. 32 Flue terminal positions - 50-V2 and 65-V2
Worcester Commercial Boiler Series – 6720814332 (2019/04)
2
25
5
7
300
600
600
6
4
Example of a flue design calculation for concentric flue system
100/150 using equivalent length method
Boiler: GB162-85 V2
Flue system: concentric 100/150
Maximum length: 18 m.
Here we have:
• 4 metre pipe (2 x 2 m)
• 2 x 90° bends (2 x 2.1 m)
The total length of this flue system = 8.2 m
Sum of length (8.2 m) < maximum length (18 m) acceptable flue
length.
Pipe = 2m
90° bend
Length = 2.1m
Pipe = 2m
Maximum length
allowed after
the boiler
(GB162-85 V2)
= 18m
Fig. 31 Example 1
3.10
Flue terminal positions
300
12
300
8
500
10
300 300
600
9
11
300 300
25
300
300
Pre-Installation
4.0 m
4.2 m
Roof terminal
90° bend
Length = 2.1m
0010026003-001
25
13
400
500
14
200
15
300
18
600
16
17
300
300
0010026004-001
16
21
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