20
TYPICAL SYSTEM SCHEMATIC
3.1.1
Dual-pipe system
Dual-pipe vacuum systems have a negative fuel pressure (de-
pression) at the burner inlet.
They typically have the tank at a lower height than the burner.
The return line should terminate in the light oil tank at the same
level as the suction line; in this case a non-return valve is not
necessary.
Should however the return line arrives over the fuel level, the
non-return valve is indispensable.
9
You are advised to use additional filters on the fuel supply
line. The Manufacturer recommends the use of a good qual-
ity fuel filter on the tank and a secondary filter (supplied
as an accessory) to protect the pump and the nozzle from
contamination.
Priming the pump
9
Before igniting the burner, make sure that the return pipe is
not obstructed; any obstruction will cause the pump's seal-
ing devices to break.
To prime the oil pump simply start up the burner and check for
a flame.
If the burner enters lockout before any fuel reaches it, wait at
least 20 seconds then turn the function selector to position (II)
"Reset burner" for at least 1 second before returning it to posi-
tion (I). Wait for the burner to complete the entire ignition cycle
again, up to the ignition of the flame.
9
The installer must ensure that the negative pressure differ-
ential in the oil feed never exceeds 0.4 bar (30 cm Hg). If this
value is exceeded, the fuel oil will release gas. Make sure
that the oil hoses are perfectly oil-tight.
(*)
m
ax
. 4
m
H
H
(*)
VIC: Fuel shut-off valve (where provided)
For the electrical connection, please refer to section “Fuel
shut-off valve VIC (not supplied)".
9
Where a fuel shut-off valve (VIC) is to be installed on the
diesel gas supply circuit to the burner, closure of the valve
must be delayed to prevent the section of hose between the
pump and the valve going into negative pressure (empty).
In parameter 2079 it is possible to set the delay time (seconds) of
the closing of the VIC valve with respect to the burner.
The value to be set must always be
≥
than the post-ventilation
time of the burner.
H (m)
L (m)
Øi (8mm)
Øi (10mm)
0
35
100
0,5
30
100
1
25
100
1,5
20
90
2
15
70
3
8
30
3,5
6
20
H
= Height difference
L
= Maximum length of suction hose
Øi
= Internal diameter of hose
The table shows the approximate maximum lengths for the
supply line, depending on the height difference, length and di-
ameter of the fuel line.
