Function Selectors - Savio GAIA 424 S Service Manual

Electronic control circuit
Primary NTC
Gas
valve
gas
inlet
Central heating temperature
fig. 37
When the boiler functions in d.h.w. (fig. 38), the signal
coming from the d.h.w. temperature probe is compared
with the signal given by the instrument panel through
the adjustment made by the user (knob
Primary NTC
Gas
valve
Domestic hot water NTC
Gas
inlet
75 ° C
fig. 38
Normally, the result of the comparison between these
two signals directly operates the adjustment elements
of the gas valve, adjusting the useful output generated
in order to stabilize the temperature of the exiting water.
If during the functioning in d.h.w. mode, the tempera-
ture of the primary circuit goes over 75° C, the useful
output is automatically reduced so that the primary cir-
cuit cannot reach excessive temperatures.
The control sequences in
are illustrated in detail in sections 9.9 and 9.10.
18
MR
RR
).
US
Secondary
heat exchanger
ES
Domestic hot water
temperature
function and in function
9.4

Function selectors

The function selectors " 6" (fig. 36 and fig. 39) are
microswitches with which it is possible to select the vari-
ous modes of functioning of the boiler.
In fig. 39 the selectors are illustrated in the configur-
ation in which the p.c.b. is set in the factory (natural gas
boiler).
6
ON (1)
fig. 39
Selector 2
f
It selects the functioning of the boiler on the basis of the
type of gas used.
It allows the selection of the maximum supply current
given to the modulator device.
To set correctly the selector follow the table of fig. 40.
Gas supply Position of selector
Natural gas On
L.P .G. Off
fig. 40
Selector 3
f
It forces the functioning of the boiler in order to permit
the optimal gas pressure at the burner to be adjusted
during the ignition phase.
The adjustment (see section 9.5) is done by means of
the potentiometer " 8"marked " ACC"(fig. 36).
After the adjustment operations bring the selector back
to the normal position (ON).
ON (1)
Normal
fig. 41
Selector 4
f
It makes it possible to select the minimum time that
must pass between two ignitions of the burner in c/h
function.
ON (1)
3 min.
fig. 42
Reignition delay
Gas pressure calibration
Gas change
No function
OFF (0)
Approx. Max current
trough the modu-
lator device
120 mA
165 mA
OFF (0)
gas pressure calibration
OFF (0)
none