Operation Sequence Of The Burner; Burner Flame Goes Out During Operation; Stopping Of The Burner - Riello RS 70/M Instrucciones De Instalación, Uso Y Mantenimiento

Start-up, calibration and operation of the burner 5
5.6

Operation sequence of the burner

Burner start-up
• 0s: TL closed.
• 5s : Start of electrical control box programme. Servomotor
starts: 130° rotation to right, until contact is made on
cam I (Fig. 7).
• 35s : The air damper arrives to the MAX. output position.
The fan motor starts up.
Start of the pre-purging phase.
• 75s : The servomotor rotates towards the left as far as the
angle set on cam III (Fig. 7) for the MIN output.
• 95s : The air damper and the gas butterfly valve adopt the
MIN output position (with cam III Fig. 7 at 65°).
• 105s : Ignition electrode strikes a spark.
The safety valve VS opens, along with the adjustment
valve VR, quick opening. The flame is ignited at a low
output level, point A.
Delivery is then progressively increased, with the
valve VR opening slowly up to MIN. output, point B.
• 108s : The spark goes out.
• 115s : The starting cycle comes to an end.
STANDARD IGNITION
M
105 108
105
35 75
M AX
M 95
115
M I N
0
5
M AX
C
B
M I N
A
0
95 115
0 sec
Steady state operation
Burner without the modulating operation kit
Once the start-up cycle is completed, the servomotor command
moves on to the TR that controls the pressure or the tempera-
ture in the boiler, point C.
(The electrical control box still continues to check the presence
of the flame and the correct position of the air and gas maximum
pressure switches).
• If the temperature is low, so the remote control TR is closed,
the burner progressively increases the output up to the MAX
value (tract C-D).
• If subsequently the temperature or pressure increases until
TR opens, the burner progressively decreases its output to the
MIN. value (section E-F). The sequence repeats endlessly.
135
D E
F
• The burner locks out when the heat request is less than the
heat supplied by the burner at MIN. output, (section G-H. The
TL opens, and the servomotor returns to angle 0°. The air
damper closes completely to reduce heat losses to a mini-
mum.
Burner with modulating operation kit
See the handbook enclosed with the adjuster.
Ignition failure
If the burner does not switch on, there is a lockout within 3s of
the electrical supply reaching the gas valve.
It may be that the gas does not arrive at the combustion head
within the safety time of 3s.
In this case increase gas ignition delivery.
The arrival of the gas at the pipe coupling is shown on the
pressure gauge of Fig. 36.
M
M AX
M
M I N
0
5
0 sec
G
H
5.7

Burner flame goes out during operation

D3815
Fig. 33
If the flame should accidentally go out during operation, the
burner will lock out within 1s.
5.8

Stopping of the burner

The burner can be stopped by:
intervening on the disconnecting switch of the electrical sup-
➤
ply line, located on the boiler panel;
removing the hood and working on the "AUT/MAN" switch of
➤
Fig. 27.
WARNING
23
GB
108
105
108
105 108
35 75
108
95
108
In the event of a burner lockout, more than two
consecutive burner reset operations could cause
damage to the installation.
On the third lockout, contact the Aftersales Ser-
vice. If further lockouts or burner faults occur, inter-
v e nt i on s m us t o nl y b e m ad e b y q ua l if i ed ,
authorised personnel (as indicated in this manual,
and in compliance with the laws and regulations
currently in force).
D3816
Fig. 34
6461