© Baxi Heating UK Ltd 2008
13
3.8.2
Horizontal Flue Systems
1. The standard flue is suitable only for horizontal
applications.
2. Maximum permissible equivalent flue lengths is:-
Horizontal Concentric
3.55m
3. Any additional “in line” bends in the flue system must
be taken into consideration. Their equivalent lengths
are:-
Concentric Pipes:
135° bend
0.5 metres
93° bend
1.0 metres
Twin Flue Pipe
135° bend
0.25 metres
91.5° bend
0.50 metres
The elbow supplied with the standard horizontal flue is
not included in any equivalent length calculations.
NOTE: Flue length is measured from point X to Y
as shown.
Horizontal
Flues
Y
X
Plume Displacement Kit
60 /100 Ø
1M Extensions, 45° & 93°
elbows are also available - see
Plume Displacement
Section 3.9
NOTE:
Horizontal flue pipes should always be installed with at least a
1.5° fall from the terminal to allow condensate to run back to the boiler.
Y
X
This bend is
equivalent to 1 metre
Total equivalent length =
A+B+C+2x90°Bends
B
A
C
This bend is
equivalent to 1 metre