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4.12
Hydraulic system
4.12.1 Double-pipe circuit
The burner is equipped with a self-priming pump which is capable
of feeding itself within the limits listed in the Tab. M.
The tank higher than the burner A
The distance "P" must not exceed 33 ft in order to avoid subjecting
the pump's seal to excessive strain; the distance "V" must not ex-
ceed 4 meters in order to permit pump self-priming even when the
tank is almost completely empty.
The tank lower than the burner B
Pump depression values higher than 0.45 bar (35 cm Hg) must not
be exceeded because at higher levels gas is released from the fuel,
the pump starts making noise and its working 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 improb-
able that the suction line fails to prime or stops priming.
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+/- H
(ft)
+ 13
+ 10
+ 6.6
+ 4.8
+ 3.3
+ 1.6
0
- 1.6
- 3.3
- 4.8
- 6.6
- 10
- 13
L (ft)
Ø
1
/
Ø
5
/
2"
8"
197
263
164
230
132
197
115
181
99
164
82
148
66
132
59
115
49
99
43
82
33
66
16
33
-
20
Tab. M
Installation
4.12.2 The loop circuit
A loop circuit consists of a loop of piping departing from and return-
ing to the tank with an auxiliary pump that circulates the fuel under
pressure.
A branch connection from the loop goes to feed the burner.
This circuit is extremely useful whenever the burner pump does not
succeed in self-priming because the tank distance and/or height
difference are higher than the values listed in the Tab. M.
Key (Fig. 20)
1
Burner
2
Pump
3
Filter
4
Manual on/off valve
5
Suction line
6
Foot valve
7
Rapid closing manual valve remote controlled (only Italy)
8
On/off solenoid valve (only Italy). See layout of electric panel
board. Electrical connections set by installer (SV)
9
Return line
10 Check valve (only Italy)
H
Pump/foot valve height difference
L
Piping length
Ø
Inside pipe diameter
27
GB
Fig. 20
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