burner shuts out immediately; when power
supply returns, the boiler will start up again
automatically.
3.4
MICROSTORAGE FUNCTION
The boiler is equipped with an insulated 4
litre hot water tank installed on its primary
circuit. The microstorage adds to the con-
venience of the system by reducing the
amount of time users have to wait for hot
water. Hot water is available at the requi-
red temperature almost instantly when
the tap is turned on. Water in the mini hot
water tank is kept at the desired tempera-
ture by a thermostatic electrical heating
element which absorbs about 30 Watts
during normal operation.
3.5
SMOKE PRESSURE SWITCH
The pressure switch is factory set at the
optimal values of 4.5-6 mm H
2
vers.) and 10-13 mm H
O ("30 BF" vers.).
2
This enables the boilers operation even with
air intake and smoke outlet pipes at the maxi-
mum limit of the length allowed. The value of
the signal to the pressure switch is measu-
red by means of an instrument connected to
the pressure take-off point (8-9 fig. 3).
3.6
FLOW PRESSURE SWITCH
SAFETY VALVE
A flow switch safety valve (12 fig. 3) inter-
venes, blocking the operation of the bur-
ner if the boiler is without water due to the
formation of an air lock in the heat exchan-
Connector "TA"
Connettore J2
KEY
TA-TA1
VZ-VZ1
ger or if the circulator is not working, or
because the primary water filter "AQUA
GUARD" is obstructed with impurities.
NOTE: If replacing the flow switch valve,
make sure that the arrow stamped on the
valve points in the same direction as the
flow of water.
3.7
SYSTEM AVAILABLE HEAD
The head available for the heating plant is
600
500
400
O ("25 BF"
300
200
100
CIRCUITO CON VALVOLE DI ZONA
CIRCUIT WITH ZONE VALVES
L
CR
CR1
TA
VZ
TA
N
NOTA: I relé vengono impiegati solo
NOTE: Relays are used only if the area
nel caso le valvole di zona siano
valves have no microswitches.
prive di micro.
Zone room stat
Zone gas valve
30
25
25
30
0
200
400
600
TA
TA
1
R
VZ
R
1
1
P-P1
Zone pump
R-R1
Zone relay
CR-CR1
Zone microvalve or relay contact
shown as a function of the flow in graph in
fig. 18.
3.8
MAINS ELECTRICITY
CONNECTION
Use a separate electricity supply to con-
nect the room stats and relative zone val-
ves or pumps. The micro or relay contact
connection is made to (J2) connector of
the circuit board after having removed the
jumper (fig. 19).
con by-pass
senza by-pass
800
1000
1200
1400
PORTATA (l/h)
FLOW RATE (l/h)
CIRCUITO CON POMPE DI ZONA
CIRCUIT WITH ZONE PUMPS
L
TA
TA1
P1
P
R
N
1600
Fig. 18
R1
Fig. 19
97