Hot Water Function - Nilfisk-ALTO NEPTUNE 4 FA Service Manual

The heat exchanger is the functional link between the heating subsystem and the water subsystem.
In "Hot water" mode the burner fan (1) draws in air and conducts it laterally into the heat exchanger
where it is routed upwards between the two jackets to the air distributor (2). This preheats the air
before it mixes with the fuel spray from the fuel nozzle (3).
Cold water is fed to the inner circuit in which the temperature is highest. This reduces in as much as
possible any condensation on the surface of the heating coil (4).
At the same time fuel is drawn in from the fuel tank by the fuel pump (5) through the filter (6). The
fuel is conducted by the solenoid valve (7) to the fuel nozzle holder (8) with the fuel nozzle (3). If no
combustion is needed, the fuel goes back to the tank on the return line (9).
The ignition transformer (10) activated in "Hot water" mode generates ignition sparks across the
electrodes (11) to ignite the fuel spray. This process is monitored by the flame sensor (12) (if
installed and activated). In normal operation the hot exhaust flows downwards and upwards
between the piping of the heating coil (4) thus warming the water in the system. The exhaust exits
through the chimney (13).
Fig.D.2: Hot water function
NEPTUNE 4 FA_EN_Ver.2.0_ 22/11
Function
1.) Burner fan
2.) Air distributor
3.) Fuel nozzle
4.) Heating coil
5.) Fuel pump
6.) Fuel filter
7.) Solenoid valve
8.) Fuel nozzle holder
9.) Fuel return line
10.) Ignition transformer
11.) Ignition electrodes
12.) Flame sensor (optional)
13.) Chimney
14.) Flame tube
15.) Flame funnel
16.) Insulation
17.) Water inlet
18.) Water outlet
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