90
60T - 280T
COSMOGAS
21 - BOILER OPERATION SEQUENCE
OPEN
CLOSED
operation
sequence
power the appli-
ance
is the electrical
frequency 60Hz?
was the neutral
phase polarity
followed?
external safety
device (contacts 103
and 104)
Heating demand
(present/absent)
contacts 12
and 13
Motorised valve (if
any) open and main
circuit pump on
Err 64
or
Err 66
Err 65
Loc 02
Err 59
Stand by
Is the supply
temperature
rising?
Is the supply
temperature
near the demand
temperature?
Every burner re-
duces output heat
The burner output
heat is less than
10%
After 3 minutes, the
corresponding motorised
valve (if any) is closed
Is the supply
temperature
decreasing?
The appliance output
heat is equal to the load
demanded
The heating demand is disa-
bled: TA opens or the external
probe is met
Is the water flow
rate greater than
15 l/min?
After 3 minutes
Err 114
The burners will
be switched off
Are all the burners
operating?
Ignition attempt
(50% of the output
heat)
Are pressure and
gas flow rate
adequate?
Burner in opera-
tion
Appliance with
only one burner?
3 minute delay
The burner output
heat
is >70%
Request for other burners
to intervene
Check fan speed
After 5 ignition at-
tempts Lock 01
No demand or
other burners
After 1 minute
Lock 12
The pumps and motorised valves
(if any) will be switched off after a
post-circulation time
Stand by
The burners keep
working
The burners keep
working
The burners keep
working
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
YES
Is the water pres-
sure greater than
1 bar?
OPEN
CLOSED
Is the heating tem-
perature
higher than the
manifold temperature?
Burner off
NO
YES