Baxi Potterton Gold FSB 30 HE manual Determining Permissible Lengths P.D.K

30	30
28	28
26	26
24	24
22	22
20	20
18	18
	30

30

9.0Plume Displacement

9.2Determining Permissible Lengths - P.D.K.

(metres)	16
	14
Exhaust
	12
70Ø	10
	8
	6
	4
	2
	0
	0	1	2	3	4
Example 1			Concentric 70/110 Flue (metres)

Flue Lengths - Not Permissible

(metres)	16
	14
Exhaust
	12
70Ø	10
	8
	6
	4
	2
	0
	0	1	2	3	4
Example 2			Concentric 70/110 Flue (metres)

Flue Lengths - OK

In the graph the solid line diagonal represents the relationship between the concentric flue assembly (and any extensions) and the 70Ø exhaust (and any extensions or additional bends).

Example 1 - Not Permissible

If, for instance, a concentric length of 3.25 metres was required and the 70Ø exhaust needed to be 10 metres the graph shows that this combination would NOT be permissible as the intersection point would be above the solid diagonal line.

	30
	28
	26
	24
	22
	20
	18		30
(metres)	16
	14
Exhaust	12
	10
70Ø
	8
	6
	4
	2
	0
	0	1	2	3	4

Concentric 70/110 Flue (metres)

Example 3

Flue Lengths - OK

Support

Bracket

70Ø Exhaust

45° Elbow

	X
Y	93° Elbow

1 metre Extension

1 metre supplied in kit

Concentric 70/110 Flue
(MUST be installed		Concentric Flue
horizontally)
Additional Accessories
A - 93° Elbow	5117381
B - 45° Elbow (Pair)	5117382
C - 1 metre 60Ø Extension	5117380

Fig. D

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 70Ø 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 metres long. Find the position of ‘2’ 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 14 metres. Therefore, the total equivalent length of the 70Ø exhaust can be up to 14 metres. Any elbow equivalencies must be accounted for i.e. 93° elbows are equal to 1 metre, each 45° elbow to 0.5 metres.

Flue Length - Worked Example

In Fig. D opposite an additional 93° elbow and pair of 45° elbows have been included in the 70Ø exhaust.

Also 3 straight extension pieces have been used.

To calculate total length:-
Length of 70Ø supplied in kit =	1 metre
3 x 1 metre Extensions =	3 metres
1 x 93° Elbow =	1 metre
2 x 45° Elbow =	1 metre (0.5 metres each)
Total 70Ø =	6 metres

After consulting the table in Example 3 it can be determined that the concentric flue could be up to approximately 3.25 metres long.

26© Baxi Heating UK Ltd 2011