Baxi 47 075 35 Installation & Servicing Instructions Manual page 36

Example 1 ­ Not Permissible If, for instance, a concentric length of 5 metres was required and the 60Ø exhaust needed to be 6 metres the
graph shows that this combination would NOT be permissible as the intersection point would be above the solid diagonal line.
Example 2 ­ Flue Lengths OK Where both lengths have been determined they can be applied to the graph to check that the installation is
permissible. For example, if it was known that 2 metres of concentric flue and 4 metres of 60Ø exhaust were required, the values could be
applied to the graph as shown in Example 2. As the point of intersection of the dotted lines is below the solid diagonal line, the combination
of lengths is shown to be acceptable.
Example 3 ­ Flue Lengths OK In the example shown, assume that the concentric part of the flue needs to be 2.3 metres long. Find the
position of '2.3' on the horizontal axis of the graph and then project upwards to the solid diagonal line. This is represented by the vertical
thick dotted line. Where this dotted line intersects with the solid diagonal line on the graph, project across to the vertical axis. As can be
seen this corresponds with 6 metres. Therefore, the total equivalent length of the 60Ø exhaust can be up to 6 metres. Any elbow
equivalencies must be accounted for i.e. 93° elbows are equal to 1 metre, each 45° elbow to 0.5 metres.
Example 1
Flue Lengths ­ Not Permissible
Example 2
Flue Lengths ­ OK
Example 3
Flue Lengths ­ OK