Pressurised One-Pipe Systems; Priming Pump - Riello BG7.1D Installation, Use And Maintenance Instructions

5.13.3 Pressurised one-pipe systems

Pressurised one-pipe systems (Fig. 20) 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.
In order to obtain one pipe working it is necessary to unscrew the
return plug 2)(Fig. 19, on page 20), remove the by-pass screw 3)
and then screw the plug 2) in again with a tightening torque of 0.5
Nm.
H
metres
0.5
1
1.5
2
D5415
H = Difference of level
L = Maximum suction line length
Ø = Inner diameter of the pipe
L metres
Ø (8 mm) Ø (10 mm)
10 20
20 40
40 80
60 100
A
Installation
H = Difference of level
L = Maximum suction line length
Ø = Inner diameter of the pipe

5.13.4 Priming pump

In the systems A and B of Fig. 21 start the burner and wait for the
priming.
Should lockout occur prior to the arrival of the fuel, await at least
20 seconds before repeating the operation.
The pump vacuum should not exceed a maximum of 0.4 bar (30
cm Hg).
Beyond this limit gas is released from the oil.
The pipes must all be perfectly sealed.
WARNING
D5414
In vacuum systems B (Fig. 21) we recommend bringing the re-
turn line to the same height as the suction line.
In this case a foot valve is not required.
Should however the return line arrive over the fuel level, a foot
valve is required.
Fig. 20
This solution however is less safe than previous one, due to the
possibility of leakage of the valve.
Tab. F
H
metres
0
0.5
1
1.5
2
3
3.5
21 GB
B
L metres
Ø (8 mm) Ø (10 mm)
35 100
30 100
25 100
20 90
15 70
8 30
6 20
Fig. 21
Tab. G
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