Potterton Gold HE A Range Installation & Service Instructions Manual page 20

Vertical
Flues
(Twin Pipe)
Y
X
Vertical
Flues
Y
X
Total Equivalent Length =
A+B+C+1x90°Bend
All vertical and angled runs must be included,
measured from the boiler adaptor (point X) to the
joint with the flue terminal (point Y). One 91.5°
bend or two 135° bends can be included without
reduction of the flue length.
If further elbows are required the flue length must
be reduced by the following amounts:-
1 metre for each 91.5° bend
0.5 metre for each 135° bend
A
X
20
© Baxi Heating UK Ltd 2008
Roof
Terminal
Y
C
B
This bend is equivalent to
1 metre
8.0 Flue Options
8.2 Twin & Vertical Flue Systems
1. Maximum permissible equivalent flue lengths are:-
(60/100)
Vertical Concentric 10 metres
Vertical Twin Pipe 15 metres
2. Any additional "in line" bends in the flue system must be
taken into consideration.
Their equivalent lengths are:-
Concentric Pipes:
135° bend
93° bend
Twin Flue Pipe
135° bend
91.5° bend
The elbow supplied with the standard horizontal telescopic
flue kit is not included in any equivalent length calculations
NOTE: Flue length is measured from point X to Y as
shown.
The total equivalent length for this example is
= 6.5 metres.
Equivalent
Length Value
1m extension
1m
135°bend 0.25m
91.5°bend 0.5m
Equivalent Length Air Duct = 6.5m
Equivalent
Length Value
1m extension 1m
135°bend 0.25m
91.5°bend
0.5m
Equivalent Length Flue Duct = 6.5m
(80/125)
20 metres
0.5 metres
1.0 metres
0.25 metres
0.50 metres
AIR DUCT
N o of Sub total
fittings/pipes
5 5.0m
2 0.5m
2 1.0m
FLUE DUCT
N o of Sub total
fittings/pipes
5 5.0m
2 0.5m
2 1.0m