11
2.7.2
Separate-pipe kit accessories
In addition to the separate-pipe kit, also available on
request are the following (Fig. 14):
– 90° pipe elbow MF ø 80 (Code 8077404);
– 90° pipe elbow MF ø 80 with intake (Code 8077407);
– extension ø 80 , length 1000 (Code 8077303);
– extension ø 80, length 130 with intake (Code
8077304);
– air-intake terminal ø 80 (Code 8089500);
– discharge terminal ø 80 (Code 8089501);
– locking junction for separate flue kits ø 80 (n° 5) (Code
8092700);
– int.-ext. ring kit ø 80 (Code 8091500);
– 45° elbow MF ø 80 (Code 8077406);
– condensation outlet ø 80 (Code 8092800).
The distance between the boiler and air-intake or flue-
outlet point is not fixed, but must be determined accor-
ding to the particular case by adding together the head
losses of both pipes. To make the calculation, take into
account the following parameters:
– for every metre of pipe ø 80 (intake or outlet), the ave-
rage head loss is 0.21 mm H
2
O;
– for every pipe bend ø 80, the average head loss is
0.35 H
2
O.
NOTE: The maximum head loss allowed for both
pipes (intake and outlet) must not exceed 5 mm H
2
O.
Example:
Assuming that the length of each pipe is 4 metres, and 2
bends are made, the head loss will be
8 metres of pipe ø 80 x 0.21
=
1.68 mm H
2
O
2 - 90° elbows ø 80 x 0.35
=
0.70 mm H
2
O
Total head loss
2.38 mm H
2
O
With this total head loss, remove four sectors of diaph-
ragm to be used in the air-intake pipe (Fig. 13/a).
Below are illustrated some of the connecting systems that
may be adopted (Fig. 14).
Murelle 20 BF
Murelle 25 BF
Sectors of diaphragm
Total head loss
Sectors of diaphragm
Total head loss
to remove
mm H
2
O
Pa
to remove
mm H
2
O
Pa
None
0 ÷ 1
0 ÷
9.8
1
0 ÷ 1
0 ÷
9.8
1
1 ÷ 2
9.8 ÷ 19.6
2
1 ÷ 2
9.8 ÷ 19.6
2
2 ÷ 3
19.6 ÷ 29.4
4
2 ÷ 3
19.6 ÷ 29.4
4
3 ÷ 4
29.4 ÷ 39.2
6
3 ÷ 4
29.4 ÷ 39.2
6
4 ÷ 5
39.2 ÷ 49.0
Remove diaphragm
4 ÷ 5
39.2 ÷ 49.0
Remove diaphragm
5 ÷ 6
49.0 ÷ 58.8
TABLE 6
KEY
1 Blind flange
2 Outlet pipe flange
3 Self-tapping screw
4 Sponge-rubber gasket
5 Air-intake pipe collar
6 Sectores diaphragm ø 38
7 Air deflector code 6257504
6
SECTOR OF DIAPHRAGM
Fig. 13/a
