air in the pipes. It may occur if the
gas cock is closed or if the winding of
one of the valve coils is interrupted,
thus preventing it from opening.
– There is no spark
In the boiler you will only notice the
gas flow to the burner, after 10
seconds it shuts down.
It may be due to the fact that the elec-
trode cable is disconnected or is not
properly fixed to the terminal 10; or
the equipment transformer is burnt.
– No ionisation
From the time of the starting you
can observe the electrode continuos
sparking even if the burner is on.
After 10 seconds the sparking stops
and so does the burner, while the
lock-out lamp appears to be on.
It occurs if the phase and neutral posi-
tion on the terminal board has not
been observed. The detection electro-
de cable is disconnected or the elec-
trode itself is earthed; the electrode is
very worn-out and needs replacing.
The sudden lack of voltage causes the
immediate shutdown of the burner and
when the voltage is restored the boiler
will automatically restart.
3.1.2 Ionization circuit
The ionization circuit shall be checked
with a normal microammeter, or even
better, with a digital microammeter
with a 0÷50 µA range. The microam-
meter terminals shall be electrically
connected in series to the ionisation
electrode cable. Under standard con-
ditions the value varies from 4÷6 µA.
The minimum ionization current value,
at which the equipment may shut
down, is approximately 1 µA. In this
case it will be necessary to check that
there is a good electric contact and to
check the wear of the electrode tip and
of its ceramic protection.
3.2 SMOKE SAFETY DEVICE
The smoke stat provides a protection
against the discharge of flue gas into
the atmophere (3 fig. 2).This control
device stops the gas valve if the flue
gas is descharged into the boiler room
is continuous way and in such quanti-
ties as to become dangerous.
To start the boiler again, switch off the
power, then remove the smoke stat
cover and reset the button below.
If the thermostat continues to trip off,
it will be necessary to check the flue
thoroughly, making all the necessary
changes to ensure it works properly.
On the “RX 37÷55” models, the smoke
stat capillary on the back of the boiler shall
be put into the 12.5 ø hole of the drought-
diverter support bracket and fixed to it
with the fitting and the M12 lock nut
already mounted on the capillary (fig. 6).
3.3 SAFETY STAT
In case the boiler temperature
exceeds 95°C the safety stat (6 fig. 2),
will extinguish the pilot burner thus
shutting off the gas flow to the pilot
and main burner. “RX 19-26” models
are equipped with safety stat with
automatic resetting, and “RX 37÷55”
with manual resetting. Should the stat
with manual resetting trip off, it will be
necessary to unscrew the cover and
reset the button below for the pilot bur-
ner to restart.
3.4 CIRCULATING PUMP
PERFORMANCE CURVES
The “RX PVA” boilers can be equipped
with either EURAMO NYL 40/25 or
GRUNDFOS UPS 25/50 circulating
pumps. Both have a built-in speed selec-
tor for adjusting head and capacity.
Head and capacity performance curves
of the standard circulating pump, at dif-
ferent speeds, are given in fig. 7-8.
NOTE: Before starting the boiler
check that the circulating pump is
not locked.
46
GR
RO
RUS
SCG
IT
ES
PT
GB
KEY
1 Smoke stat capillary
2 M12 lock out
3 Capillary
support bracket
4 M12 fitting
Fig. 6
EURAMO NYL 40/25 GRUNDFOS UPS 25/50
Fig. 7 Fig. 8
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