A.O. Smith 120 through 250 Series - Manual (Page 28)

Installation
28 Instruction manual BFC
3
is
Explanation of type of appliance
Note
Make sure that the chimney discharges into an area where this is permitted
for this category of appliance.
3.9.3 Concentric connections
The table shows the requirements for concentric systems.
Warning
Install flue gas discharge pipe runs with a run-off of 5 mm per metre.
Flue gas discharge requirements for concentric systems (C13, C33)
Attention
Both conditions stated in the table must be fulfilled.
Even if there are less bends than the stated maximum, the maximum pipe
length may not be exceeded.
Even if the total pipe length is less than the stated maximum, the maximum
number of bends may not be exceeded.
The following example illustrates how to use the table.
Practical example of concentric flue gas discharge
Example
The figure shows a BFC 30 installation. The appliance must be fitted with 25 m
of concentric pipe (C13/C33) and four 90 degree bends. We need to check
whether this configuration complies with the requirements stated in the table.
Type of appliance Description
B23 Air for combustion is drawn from the boiler room.
C13 Concentric and / or parallel wall flue terminal
C33 Concentric and / or parallel roof flue terminal
C43 Appliances on common air supply and flue gas discharge (concentric and / or
parallel) in multi-storey building.
C53 Air supply and flue terminal types mixed.
C63 Appliances supplied without flue components and / or terminal. These
appliances must be installed in compliance with local regulations.
Appliance Diameter Maximum length Maximum
number of 90º
bends
BFC 28 80/125 mm 40 m 7
BFC 30 100/150 mm 40 m 7
BFC 50 100/150 mm 40 m 7
BFC 60 100/150 mm 15 m 4