Hydraulic System; Fuel Supply; Double-Pipe Siphon-Type Systems; Double-Pipe Suction-Type Systems - Riello RL 42 BLU Instrucciones De Instalación, Montaje Y Funcionamiento

5.8

Hydraulic system

5.8.1

Fuel supply

The burner is equipped with a self-priming pump which is capable
of feeding itself within the limits listed in the table at the side.
There are three types of fuel hydraulic circuits:
– Double-pipe circuits (the most common)
– Single-pipe circuits
– Loop circuits
According to the burner/tank layout, either of two fuel supply sys-
tems can be used:
• siphon-type (with the tank higher than the burner)
• suction-type (with the tank lower than the burner)
5.8.2

Double-pipe siphon-type systems

The distance P (A, Fig. 15) must not exceed 10 meters in order
to avoid subjecting the pump's seal to excessive strain; the dis-
tance V must not exceed 4 meters in order to permit pump self-
priming even when the tank is almost completely empty.
5.8.3

Double-pipe suction-type systems

Pump depression values higher than 0.45 bar (35 cm Hg)(B,
Fig. 15) must not be exceeded because at higher levels gas is re-
leased from the fuel, the pump starts making noise and its work-
ing life-span decreases.
It is good practice to ensure that the return and suction lines enter
the burner from the same height; in this way it will be more im-
probable that the suction line fails to prime or stops priming.
Useful suggestions for both systems A and B
➤ Use copper pipes whenever possible.
➤ Any curves used in the system should be made with the
widest possible radius.
➤ Use biconic connectors at both ends of the pipe.
➤ Whenever the burner is installed in areas with extremely
cold winter climates (temperatures lower than - 10°C), we
recommend insulating both the tank and the piping. Avoid
the smallest of the three pipe diameters provided in the
Table and lay the piping along the most sheltered route pos-
sible. The paraffin in the fuel begins to solidify below 0°C,
and the filters and nozzle begin to clog accordingly.
➤ Install a filter on the suction lines with a transparent plastic
bowl if possible in order to permit the regular flow of fuel and
quick checking of the state of the filter.
➤ The return pipe does not require an on/off valve, but if the
user desires to insert one, a lever-type valve should be
selected which clearly indicates when the valve is open or
closed (if the burner starts with the return pipe closed, the
sealing organ located on the pump shaft will break).
➤ Copper pipes must be installed to a position with respect to
the burner that allows the latter to be fully retracted on its
slide bars without stretching or twisting the flexible hoses.
➤ If more than one burner is operating in the same room, each
one must be equipped with its own suction pipe; the return
pipe may be shared by all, providing it is sufficiently sized.
➤ The suction line must be perfectly airtight. In order to check
the seal, close the pump's return line. Install a T union on
the vacuum meter attachment.
On one branch of this T install a pressure gauge and on the
other branch inject air at a pressure of 1 bar. After the air
injection, the gauge must remain at a constant pressure.
Installation
+H -H
m
+4
+3
+2
+1
+0,5
0
-0,5
-1
-2
-3
-4
Legend (Fig. 15)
H Pump/Foot valve height difference
L Piping length
values calculated for light oil:
• viscosity
• density
• temperature
• max. altitude
ø Inside pipe diameter
1 Burner
2 Pump
3 Filter
4 Manual on/off valve
5 Suction line
6 Foot valve
7 Return line
15 GB
20101772
L m
ø 8 mm ø 10 mm
52 134
46 119
39 104
33 89
30 80
27 73
24 66
21 58
15 43
8 28
- 12
6 cSt / 20 °C
3
0,84 kg/dm
0 °C
200 m (s.l.m.)
Fig. 15
ø 12 mm
160
160
160
160
160
160
144
128
96
65
33
Tab. G
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