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104

4.1

D.H.W. TANK UNIT

The. enamelled. D.H.W..tank. comes. with.
a.magnesium.anode.to.protect.the.boiler.
and.an.inspection.flange.for.checking.and.
cleaning..

The magnesium anode must

be checked annually and replaced if it
is worn.

It.is.advisable.to.place.a.sluice.

gate. at. the. entrance. of. the. D.H.W.. tank.
unit.which,.apart.from.the.total.closure,.
allows.the.regulation.of.the.supply.capa-
city.

When the boiler does not produce hot
water, make sure that the air has been
released by acting on the manual vents
after having turned the main switch off.

4.2

CONTROL OF THE GAS

PRESSURE UPSTREAM

OF THE BOILER

If.the.upstream.pressure.is.between.11.5.
and. 15. mbar. the. boiler. is. functioning,.
though.at.an.inferior.maximum.nominal.
power..In.case.of.pressure.less.than.11.5.
mbar.the.gas.pressure.switch.acts.

4.3

GAS VALVE

The.boiler.model.SIT.845.SIGMA.(fig..14).
is. produced. with. gas. valve. set. at. two.
pressure. values:. maximum. and. mini-
mum,. that. correspond. according. to. the.
type. of. gas. to. the. values. indicated. in.

Table 2

The.setting.of.the.gas.pressure.at.mini-
mum.and.maximum.values.is.carried.out.
by.SIME:.variations.are.discouraged..
Only.in.the.passing.from.one.type.of.gas.
supply. (methane). to. another. (propane).
is. a. change. in. the. working. pressure.
allowed.

Such an operation must be carried out
by authorised personnel, or the guaran-
tee will lose validity. Once the change in
working pressure has been carried out,
seal the regulators.

When.proceeding.with.the.setting.of.the.
pressure,.it.is.necessary.to.follow.a.pre-
established. order,. regulating. first. the.
MAxIMUM.and.then.the.MINIMUM.

4.3.1 Maximum and minimum

pressure adjustment

In. order. to. carry. out. the. setting. of. the.
maximum. proceed. in. the. following. way.
(fig..15):
–. Connect. a. differential. manometer. as.

shown.in.fig..14.

–. Remove.the.plastic.cap.of.the.modu-

lator.(1).

–. Start.the.boiler.by.pressing.on.the.four.

way.switch.

–. Place.the.heating.potentiometer.knob.

on.the.maximum.value.

–. Using.a..ø.10.wrench.turn.the.nut.(3).to.

find.the.maximum.pressure.as.shown.

in.

Table 2

:.to.reduce.the.pressure.turn.

the.nut.anti-clockwise,.to.increase.the.
pressure.turn.the.nut.clockwise.

–. Turn. off. and. turn. on. the. burner. 2-3.

times.to.verify.that.the.pressure.corre-
sponds.to.the.values.given.in.

Table 2

After. having. regulated. the. maximum.
pressure,.proceed.with.the.setting.of.the.
minimum.pressure.
–. Disconnect. the. electric. supply. of. the.

modulator.

–. With. the. heating. potentiometer. knob.

on. the. maximum. value. and. the. bur-
ner. alight,. holding. the. nut. (3). blocked,.
turn. the. screw. (2). to. find. the. minimum.
pressure. value. as. shown. in.

Table 2

:. to.

decrease.the.pressure.turn.the.nut.anti-
clockwise. and. to. increase. the. pressure.
turn.the.nut.clockwise.

–. Turn. on. and. turn. off. the. burner. 2-3.

times.to.verify.that.the.pressure.corre-
sponds.to.the.values.given.in.

Table 2

–. Reconnect.the.electrical.supply.of.the.

modulator.

–. Replace.the.plastic.cap.(1).

4.4

ADJUSTMENT OF HEATING

OUTPUT

.
To. regulate. the. heat. putput,. modifying.
the. factory. settings,. which. is. the. mini-
mum. thermal. power. for. each. model.
(17.8.-.24.1.kW),.it.is.necessary.to.work.
with.a.screwdriver.on.the.trimmer.of.the.
heating.power.(10.fig..10)...
To.increase.the.operating.pressure.turn.
the. trimmer. in. a. clockwise. direction,. to.
decrease.the.pressure.turn.the.trimmer.
in.an.anti-clockwise.direction..
To.facilitate.the.search.for.the.adjusting.
of.the.heating.power.the.diagrams.pres-