A.O. Smith 120 through 250 Series - Manual (Page 31)

Instruction manual BFC 31
is
3.9.4 Parallel connections
The table states the maximum pipe lengths for parallel systems. The maximum
pipe length depends on the chosen diameter.
Warning
Install flue component pipe runs with a run-off of 5 mm per metre.
Flue gas outlet requirements for parallel systems
You must use the longest pipe when calculating the pipe length. For example, if
the chimney pipe is 35 metres and the air supply pipe is 32 metres, use 35
metres as the length for the calculation. Next, add the L
equivalent
for every 90°
and 45° bend to this 35 metres, in both the air supply and flue gas outlet. The
following practical example illustrates how to use the table.
Practical example of parallel flue gas outlet
Example
The diagram shows a BFC 30. This has to be fitted with a 25m parallel pipe
100mm in diameter, plus eight 90-degree bends. The configuration must be
checked for compliance with the requirements stated in the table.
Appliance Diameter 1 Maximum
total length L
equivalent
90º bend
L
equivalent
45º bend
BFC 28 80mm 25m 3.9m 1.1m
BFC 30 100mm 80m 4.6m 1.2m
BFC 50 100mm 45m 4.6m 1.2m
BFC 60 100mm 25m 4.6m 1.2m
BFC 28 100mm 100m 4.6m 1.2m
BFC 30 130mm 100m 2.4m 1.4m
BFC 50 130mm 100m 2.4m 1.4m
BFC 60 130mm 100m 2.4m 1.4m
1) Parallel systems with diameter of 130mm or 150mm. If the maximum total
length for a diameter of 130mm is insufficient, 150mm diameter must be used.
Any diameter enlargement must be carried out on both air supply and flue gas
outlet.