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there is air in the pipes. It may be caused
by the gas cock being closed or by one of
the valve coils having a break in the win-
ding, so that the valve cannot open.

–

Ignition electrode fails to spark

In the boiler, only the gas to the burner
is seen to open. After 10 sec. the war-
ning light indicating equipment “lock-
out” lights up.
This may be due to a break in the wire of
the electrode or to the wire not properly
fastened to the electric terminal of the
control box;

–

No detection of flame

The  continuous  spark  discharge  of  the
electrode  is  noted  starting  from  ignition
even though the burner is lit.
Af ter  10  seconds  have  elapsed,  the
sparks  cease,  the  burner  goes  out,  and
the  warning  light  indicating  equipment
“lock-out” lights up.
There  could  have  a  break  in  the  wire  of
the  sensing  electrode  or  the  electrode
itself  is  touching  earth:  the  electrode  is
worn  out  and  needs  replacing.  The  con-
trol box is defective.

When there is a sudden voltage failure, the
burner shuts out immediately; when power
supply returns, the boiler will start up again
automatically.

3.4

“20 OF - 30 OF” SMOKE
SAFETY DEVICE

This is a safety device to prevent the back-
flow of exhaust fumes into the room due to
inefficiency or a partial blockage in the flue
duct  (8  fig.  3).  The  safety  device  goes  into
action by blocking operation of the gas valve
when  the  return  of  the  smoke  into  the
ambience  is  continuous  and  in  quantities
that might constitute a danger. 10 minutes
after the  tripping, the board automatically
attempts  a  restart  and  returns  the  boiler
back to normal operation if the fumes devi-

ce has reset. Should the boiler continue to
“lock out”, it will be necessary to make a
careful check on the flue pipe, making all the
necessary modifications and amendments
so that it can work properly.

3.5

“25 BFR - 25 BF - 30 BF - 25 BFT”
SMOKE PRESSURE SWITCH

The pressure switch is factory set at the
optimal values of 4.5-6 mm H

O (

“25”

vers.)

and 10-13 mm H

O (

“30”

vers.).

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/a).

3.6

FLOW PRESSURE SWITCH
SAFETY VALVE

A flow switch safety valve (12 fig. 3 - 3/a -
3/b) intervenes, blocking the operation of
the burner if the boiler is without water
due to the formation of an air lock in the

heat  exchanger  or  if  the  circulator  is  not
working,  or  because  the  primary  water  fil-
ter  (16  fig.  3/a)  is  obstructed  with  impuri-
ties.

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
shown as a function of the flow in graph in
fig. 26.

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. 27).

CR1

Connettore J2