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Vertical Flue System
Examples (Twin Pipe)
(ii)
(i)
(ii)
(i)
8.0Flue Options
8.2Twin & Vertical Flue Systems
Concentric
The maximum equivalent lengths are 4m (vertical). Their lengths exclude the standard elbow and terminal assembly (vertical).
Twin Flue
The total maximum equivalent flue length is 150m. NOTE: Each 1m of flue duct should be calculated as 2m.
Any additional “in line” bends in the flue system must be taken into consideration. Their equivalent lengths are:
Concentric Pipes: | 135° bend | 0.5 m |
| 93° bend | 1.0 m |
Twin Flue Pipe: | 135° bend (air duct) | 1.3 m |
| 135° bend (flue duct) | 2.6 m |
| 90° bend (air duct) | 4.8 m |
| 90° bend (flue duct) | 9.6 m |
IMPORTANT: All flue systems must be securely supported at least once every metre. Suitable pipe supports are available as accessories.
Vertical Flue System Examples
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:-
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1 metre for each 91.5° bend | (ii) |
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0.5 metre for each 135° bend |
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B
Roof Terminal
C
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| The total equivalent length | |
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| for this example is | |
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| 17.2 + 34.4 = 51.6 metres. | |
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| AIR DUCT |
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| Equivalent | No of | Sub total |
| Length Value | fittings/pipes |
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1m extension | 1m | 5 | 5.0m |
135°bend | 1.3m | 2 | 2.6m |
91.5°bend | 4.8m | 2 | 9.6m |
This bend is equivalent to 1 metre
A
(i)
| Equivalent Length Air Duct = 17.2m | ||
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| FLUE DUCT |
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| Equivalent | No of | Sub total |
| Length Value | fittings/pipes |
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1m extension | 2m | 5 | 10.0m |
135°bend | 2.6m | 2 | 5.2m |
91.5°bend |
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9.6m | 2 | 19.2m | |
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| Equivalent Length Flue Duct = 34.4m | ||
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© Baxi Heating UK Ltd 2011 | 21 |