Page 7
NOL Compact Modulating
Existing Appliances
In preparing the appliance to receive the NOL oil
burner, a careful inspection should be made of its
condition after it has been cleaned thoroughly to
remove all adhering tars, scale and dirt.
Combustion Chamber Conditions
When the burner is fitted to an appliance designed
to work under balanced or negative combustion
chamber conditions, the over-fire draught must not
exceed 0.25 mbar.
Should the over-fire draught exceed this figure, then
steps should be taken to reduce it to this level.
I
NSTALLATION
General
Check that the burner is appropriate for the
appliance rating. Detailed burner performance
data is given on page 19.
Fitting to the Appliance
If the burner is to be fitted to a new packaged unit,
refer to the manufacturers recommendations.
If the burner is being fitted to an existing appliance,
prepare the mounting flange as detailed on page
5.
Ensure the joint between appliance and burner is
effectively sealed with the gasket provided.
Unless the appliance manufacturer specifies
extensions, the flame tube should be flush with
the inner face of the appliance combustion
chamber.
Oil Supply Connections
Connect the oil supply to the burner oil pump
using the flexible pipes supplied. Refer to the
burner oil system diagram on page 8.
Electrical Power Connection
Connect a three-phase, 50 Hz electrical supply to
the burner, observing all applicable Codes and
Standards. The electrical connections required are
shown on page 9 and in the wiring diagram
contained in the instruction pack attached to the
burner. These diagrams also show the auxiliary
control connections, which must be made.
If the burner is supplied as part of a packaged
appliance/burner unit refer to the appliance
manufacturers instructions.
B
URNER
A
IR
C
ONTROLS
A motorised, cable driven air flap controls the air
for combustion. It is located inside the air inlet.
Air Diffuser
The air diffuser creates a pressure drop to ensure
good fuel/air mixing and flame stability.
B
URNER
O
IL
C
ONTROLS
Oil Nozzle
The oil nozzle is of the spill-back type and is fitted
to the front end of the inner assembly and located
in the flame tube.
The nozzle should be sized to match the rating
and turndown requirements of the appliance.
Oil Control Train
The oil control train consists of a high pressure fuel
pump driven by the burner fan motor.
The oil nozzle throughput is controlled by a
variable orifice regulator situated in the return
supply oil line, and actuated by the Modulating
Unit described below. Solenoid operated normally
closed valves in the feed and return lines act as
the safety shut off for the nozzle.
Modulating Unit
The Nu-way modulating unit consists of a reversible
servomotor, which is directly coupled to the
camshaft of the modulating unit. Two adjustable
cams are mounted on this shaft, one of which is
connected to a flexible cable operating the burner
air inlet control damper and is of the variable
contour type (see fig. 2 on page 12). The second
cam is the modulating oil cam and is illustrated in
fig. 1. The
Burner Oil System
Drawing on page 8
shows the burner hydraulic circuit. Oil for
combustion is drawn from the supply through a
fixed displacement pump and supplied direct to
the burner nozzle. A return line from the back of
the nozzle is connected to a spill regulating valve
which regulates the oil pressure at the nozzle
according to the position of an internal piston
which is actuated by the oil control cam in the
modulating unit.
There is a well defined relationship between the
delivery of fuel through the nozzle and pressure
behind the nozzle, therefore movement of the oil
cam modulates the nozzle output and hence the
output of the burner.
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