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STZM@ ed 05/04 ZEUS Maior @
Technical DocumentationTechnical Documentation
Central heating antifreeze request.
When the temperature read by the NTC delivery probe (B1)
drops below 4°C, the board enables ignition and keeps the
burner working depending on the output set with the mini-
mum central heating power adjustment trimmer (MIN.HEAT.
POW.) until a boiler temperature of 42°C is reached.
Domestic hot water antifreeze request.
If the temperature read by the domestic hot water NTC probe
(B2) drops below 4°C, the board enables ignition and keeps
the boiler working at the output set with the minimum central
heating power adjustment trimmer (MIN.HEAT.POW.) until
the d.h.w. probe measures a temperature of 8°C.
e water in the primary circuit is kept below 42°C during
operation because if this temperature is reached the board
switches the burner off.
Central heating request with the Remote Con-
trol.
If the conditions detected by the Remote Control (CAR)
require operation in the central heating mode (the SUM-
MER/WINTER selector on “WINTER”, hourly programmer
request, room temperature setting higher than what is read), the
low voltage circuit starts the circulator (M1) by means of the
K1 relay and powers motor (M) of the 3-way diverter valve
(M3) by way of the K3 relay contact.
If the contact of the system pressure switch (S7) is closed and
the temperature measured by the NTC delivery probe (B1) is
below the temperature set with the Remote Control (CAR)
heating potentiometer, the low voltage circuit energises the
K2 relay.
is powers the control unit (IGN. BOARD) and starts the
ignition cycle which is the same as for the central heating
request with the room thermostat.
During operation, the current signal to the coil is varied in
a way directly proportionate to the difference between the
temperature set with the heating potentiometer (HEAT.)
and that measured with the NTC delivery probe (B1) and, if
necessary, it reaches the maximum value set in 13.5 minutes
(MAX.HEAT.POW.).
When the set temperature is exceeded the contact of relay K2
opens and the burner switches off. Re-ignition for the same
request is inhibited for 180 s / 30 s (see central heating timer
selector “S2”).
D.h.w. request.
If the temperature read by the domestic hot water NTC probe,
located on the storage tank (B2) is below the temperature
set with the d.h.w. potentiometer (D.H.W.), the low voltage
circuit starts the boiler circulator (M1) by means of relay K1
and powers motor (M) of the 3-way valve (M3) by way of the
K3 relay contact.
When the system pressure switch micro (S7) closes as a result,
burner ignition proceeds as it does for the central heating
phase.
In the first 5 seconds after the gas valve (Y1) is powered, the
modulating coil current is limited by the setting made with
the soft ignition trimmer (IGN.POW.).
is current is then increased so as to reach (if requested) the
maximum set value immediately.
Flame modulation occurs with reference to the delivery
temperature measured by the central heating delivery probe
(B1) which is varied according to the difference between the
temperature set with the d.h.w. potentiometer (D.H.W.) and
that measured with the d.h.w. probe (B2).
When the set value is reached the burner is kept working at
minimum output and the K2 relay contact opens (burner
off) when the d.h.w. probe (B2) measures the temperature
requested by the d.h.w. potentiometer (D.H.W.).
It is closed again when the temperature drops -3°C in relation
to the temperature requested by the d.h.w. potentiometer
(D.H.W.).
If, during operation, the central heating delivery probe (B1)
measures a temperature higher than 90°C, the relay K2 contact
opens to reclose as soon as the temperature drops to 75°C.
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