6.3
Pressurised one-pipe systems
Pressurised one-pipe systems (Fig. 12) have a positive fuel pres-
sure on intake to the burner.
Usually the tank is higher than the burner, or the fuel pumping
systems are on the outside of the boiler.
●
ONLY FOR ITALY
:
Automatic shutoff device as per DM 28/4/2005.
H
metres
0.5
1
1.5
2
= difference of level;
H
= max. length of the suction line;
L
Ø i
= internal diameter of the pipe.
The installer must ensure that the supply pressure
is not above 0.5 bar.
Above that level, the pump seal is subject to too
WARNING
much stress.
In the system in Fig. 12, the table shows the maximum approxi-
mate lengths for the supply line, depending on the difference in
level, length, and the diameter of the fuel conduit.
6.3.1
Priming pump
It is sufficient to loosen the vacuometer connection 6) (Fig. 11)
and wait until fuel flows out.
20015403
Hydraulic system
SYSTEM NOT PERMITTED
IN GERMANY
●
D5414
L metres
Øi
Øi
8 mm
10 mm
10
20
20
40
40
80
60
100
6.4
Vacuum systems
Vacuum systems (Fig. 13 and Fig. 14) have a negative fuel pres-
sure (depression) on intake to the burner.
Usually the tank is lower than the burner.
Fig. 12
●
ONLY FOR ITALY
Automatic shutoff device as per Ministry of Internal Affairsʼ regu-
lation no. 73, dated 7/29/71.
H
metres
0
0.5
1
1.5
2
3
3.5
H
= difference of level;
= max. length of the suction line;
L
= internal diameter of the pipe.
Ø i
14
GB
●
D9620
●
:
L metres
Øi
8 mm
35
30
25
20
15
8
6
Fig. 13
D9621
Fig. 14
Øi
10 mm
100
100
100
90
70
30
20