CTC Union CTC 380 IC - 7 Preheater; Function FPHB 5-LE; LE-Valve

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7. PREHEATER
7.1.1 Function FPHB 5-LE
When the boiler thermostat connects, the PTC element is energized and
oil begins to preheat. When the oil has reached the correct temperature,
the preheater thermostat closes and the burner receives the start signal.
During operations the PTC element compensates its output so that the
temperature does not become too high. If the oil temperature is low and
theoilowhigh,thepreheaterthermostatmayopenowingtothePTC
element’sinabilitytomaintainoiltemperature.
In this case it is important to use oil burner controls with a preheater
holding circuit.
7.1.1.1 LE- valve
FPHB 5-LE has an integrated shut-off valve which prevents oil drips at
start and stop. When a normal preheater is used before start, the oil
expandsandasmallquantityofoilowsoutofthenozzleoriceand
wets the outside of the nozzle.
Also, when the burner stops, a small quantity of oil forces its way out
aftertheamehasgoneout,especiallywhentherearehotcomponents
which radiate heat back to the nozzle.
The cut-off valve in the FPHB 5-LE is located immediately behind the
nozzle.Itopensat≈6.5barandclosesat≈2.5bar.
In order to achieve the intended effect when the pressure of the trapped
oil increases, it must be evacuated back to the pump. This is made possible
bythepumpsolenoidvalve’sreturn-valvefunction.
The cut-off valve can be pulled out of the preheater with the aid of an M5
screw as illustrated. When the valve is re-installed, oil pressure pushes it
toapositionallthewayforwardbehindthenozzleltersothatthevolume
in front of the valve is as small as possible.