Biasi RIVA COMBI Service Manual page 32

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Third Part
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A) J3 connector
B) J2 connector
C) Lock-out signal lamp
D) Boiler reset button
E) Function control / C.h. temperature
adjustment
F) D.h.w. temperature adjustment
G) Appliance operation lights
H) Dip-switch selectors
I) Setting jumpers
J) Ignition gas pressure adjustment (ACC.)
K) J1 connector
L) Fuse 4.0 A
3 Checking the Temperature
The Electronic control p.c.b. makes it possible to
separately adjust the c.h. water flow temperature
and d.h.w. outlet temperature.
The temperature of the water is converted into an
electric signal by means of temperature probes.
The user, setting the desired temperature with
the control panel knobs operates the variable
elements (E,F in Figure 1) of the control p.c.b.
If the power requested is lower than 40% of the
maximum power output then control is achieved
by switching ON the burner at minimum power,
then switching OFF (ON/OFF function). If the
power requested is higher, then the burner is
switched ON at maximum power and will control
by modulating to 40% of the maximum power
output.
RIVA COMBI SERVICE MANUAL – REV A
Figure 2
(edition-0106)
During the c.h. operation (Figure 2), the signal
coming from the c.h. temperature probe is
compared to the signal given by the control panel
through the adjustment made by the user (knob
in Figure 2). The result of such a comparison
operates the modulation of the gas valve,
consequently changing the useful output of the
boiler.
When the boiler functions in d.h.w. (Figure 3), the
signal coming from the d.h.w. storage tank
temperature probe is compared with the signal
given by the control panel through the
adjustment made by the user (knob in Figure 3).
Normally, the result of the comparison between
these two signals directly operates the
adjustment elements of the gas valve
modulation device, adjusting the useful output
generated in order to stabilize the temperature of
the exiting water.
If during the d.h.w. mode operation, the
temperature of the primary circuit goes over
75°C, the useful output is automatically reduced
so that the primary circuit cannot reach excessive
temperatures.
The control sequences in function winter and in
function summer are illustrated in detail in
sections 14 and 15.
4 Operation Lights
The Control p.c.b. is provided with three lamps
(L.E.D. indicators) G in Figure 1 that give optical
information during the operation of the boiler.
Control p.c.b. 11.62
75 °C
Figure 3
6-2