AGA
Burner control unit BCU 370
Technical Information · GB
6 Edition 01.19
• For modulating, forced draught burners for gas of unlimited
capacity in intermittent or continuous operation
• Control of fan and butterfly valve
• Simple system set-up thanks to optional tightness control and
integrated ignition unit
• Easy start-up and maintenance thanks to Manual operating mode
• Optionally available with integrated fieldbus interface for simple
wiring
Contents
Burner control unit BCU 370 ........................1
Contents ............................................2
1 Application ........................................4
1.1 Applications example ..............................6
1.1.1 Modulating-controlled forced draught burner........6
1.1.2 Modulating-controlled forced draught burner with
tightness control ............................................6
1.1.3 Modulating-controlled forced draught burner with
pilot burner and tightness control ..........................7
1.1.4 Controlling the BCU via
PROFIBUS DP ...............................................8
1.1.5 Controlling the BCU and the butterfly valve via
PROFIBUS DP ...............................................8
2 Certification .......................................9
3 Function ......................................... 10
3.1 Connection diagrams .............................10
3.1.1 BCU 370 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1.2 BCU 370 with actuator IC 20........................ 14
3.1.3 Capacit y control by adjusting the valve between
the Open position and a separate Min position........... 15
3.1.4 BCU 370..B1 with PROFIBUS DP ...................16
3.1.5 Assignment of connection terminals ................17
3.2 BCU 370 program sequence .....................19
3.2.1 Normal start-up ..................................... 19
3.2.2 Quick start, butterfly valve waits in the Ignition
position.....................................................21
3.2.3 Quick start, butterfly valve waits in the Closed
position....................................................23
3.2.4 Start-up without pre-purge, butterfly valve waits
in the Closed position ..................................... 25
3.2.5 Controlled air flow ....................................27
3.3 Tightness control .................................28
3.3.1 Program sequence ..................................30
3.4 PROFIBUS DP ....................................32
3.4.1 Safety-related control signals.......................32
3.4.2 BCSoft ...............................................33
3.4.3 Configuration, master-slave procedure .............33
3.4.4 Addressing...........................................33
3.4.5 Network technology .................................34
3.4.6 Configuration........................................34
3.4.7 Bus communication .................................34
3.5 Program status ...................................36
3.6 Fault message (blinking)..........................37
3.6.1 Reaction to process faults ..........................38
4 Parameters ...................................... 40
4.1 Scanning the parameters .........................42
4.2 Flame control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.2.1 Burner flame signal.................................. 42
4.2.2 Burner switch-off threshold......................... 42
4.2.3 UVS check (1× in 24 hours) ..........................43
4.3 Behaviour during star t-up ....................... 44
4.3.1 Minimum burner pause time tBP ....................44
4.3.2 Burner start-up attempts ...........................44
4.3.3 Switch-on delay time t
4.3.4 Pre-ignition time t
st
4.3.5 1
t
SA1
4.3.6 1
4.3.7 2
4.3.8 2
safety time on start-up, burner/pilot burner
........................................................46
st
flame proving period, burner/pilot burner t
nd
safety time on start-up, main burner t
nd
flame proving period, main burner t
.............................45
E
................................45
VZ
FS1
.......47
SA2
.........47
FS2
..46
4.4 Behaviour during operation...................... 48
4.4.1 Minimum operating time tB .........................48
4.4.2 Controller enable signal delay time t
4.4.3 Safety time during operation t
SB
.............48
RF
...................48
4.4.4 Restart after flame failure during operation ........49
4.4.5 Last fault signal .....................................49
4.4.6 V2 during burner operation .........................50
4.5 Monitoring/tightness control ....................51
4.5.1 Min. gas pressure monitoring ........................51
4.5.2 Digital input function.................................51
4.5.3 Air monitoring during pre-purge .................... 52
4.5.4 Air monitoring during operation.....................53
4.5.5 Tightness controll, test period t
...................54
P
BCU 370 · Edition 01.19 2
= To be continued
▼
4.6 Air control .........................................56
4.6.1 Valve control .........................................56
4.6.2 Pre-purge............................................56
4.6.3 Quick start starts in... .................................57
4.6.4 Pre-purge time t
4.6.5 Post-purge time t
4.6.6 Fan run-up time t
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
PV
.................................59
PN
.................................60
GV
4.7 Control using PROFIBUS DP .....................61
4.7.1 Bus control activation ................................61
4.7.2 Bus control limitation.................................61
4.8 Manual mode .....................................63
4.8.1 Operating time in Manual mode ....................63
4.9 Fault messages ...................................64
4.9.1 The last 10 fault messages..........................64
4.10 Password ........................................64
4.10.1 User-defined password . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
5 Selection ........................................ 65
5.1 Type code .........................................65
6 Project planning information .................... 66
6.1 Cable selection .................................. 66
6.1.1 Ionization cable......................................66
6.1.2 UV cable .............................................66
6.1.3 Ignition cable ........................................66
6.2 Fan control........................................67
6.3 Controlling the butterfly valve ....................67
6.4 Safety interlock (limits) ...........................67
6.5 Too many remote resets ..........................67
6.6 Protecting the ignition unit from overload ...... 68
6.7 Wiring ............................................ 68
6.7.1 Single-electrode operation with external ignition
unit.........................................................68
6.8 BCU switched off ................................ 68
6.9 Note on EC type-examination or CSA and FM
approval ...............................................69
6.10 Contact fuses ...................................69
6.11 Installation ......................................69
6.12 Protective circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69
6.13 BCSoft...........................................69
7 Flame control ..................................... 70
7.1 ...with flame rod....................................70
7.2 ...with UV sensor ...................................70
8 Accessories.......................................71
8.1 High-voltage cable ...............................71
8.2 BCSoft ............................................71
8.2.1 Opto-adapter PCO 200 ..............................71
8.3 Radio interference suppressed terminal boots...71
8.4 Connection kit BCU 370..........................71
8.5 Set of stickers BCU 370...........................71
8.6 GSD master data file for BCU 370..B1 ............72
9 Technical data ....................................73
9.1 PROFIBUS DP ....................................74
9.2 Operating controls and dimensions ..............75
9.3 Converting units ..................................76
10 Legend ..........................................77
11 Glossary .........................................78
11.1 Safety shut-down ................................78
11.2 Fault lock-out....................................78
11.3 Warning signal ...................................78
11.4 Timeout 25 s/250 s .............................78
12 Annex .......................................... 79
12.1 Status and fault messages for PROFIBUS DP ..79
Feedback ...........................................82
Contact.............................................82
BCU 370 · Edition 01.19 3
= To be continued
▼
Application
BCU 370
1 Application
The BCU 370 burner control unit controls, ignites and
monitors industrial forced draught burners of unlimited
capacity in intermittent or continuous operation.
It can be used for directly ignited forced draught burn-
ers or forced draught burners ignited with pilot burner.
The BCU 370 activates the fan and sets the connected
butterfly valve to Pre-purge and Ignition position. After
pre-purge and burner start, the enable signal is issued
to an external controller which positions the butterfly
valve in accordance with the capacit y demand. Post-
purge occurs after the end of burner operation. The
burner control unit BCU 370 monitors the gas and air
pressure. An optionally integrated tightness control
BCU 370 · Edition 01.19 4
Lower section Upper section
function checks the valves with an external gas pres-
sure switch.
Programmability by means of the optical interface and
BCSoft PC software guarantees optimum adaptation to
the relevant application. Adjustable start-up attempts
and automatic restart which can be activated ensure
the high flexibility of the burner equipment.
The quick-start option allows standard-compliant star t-
up of the forced draught burner without pre-purge
after controlled shut-down. This avoids unnecessary
admission of air into the combustion chamber. The heat
output is available as quickly as possible after a temperature demand.
▼
Application
The program status, the unit parameters and the level
of the flame signal can be read directly from the BCU.
An integrated Manual mode allows manual start of the
burner and setting of the butterfly valve position inde-
pendently of the central control system. The BCSoft
operator-control and setting software provides a pow-
erful tool for commissioning and servicing.
To reduce the installation and wiring costs, Honeywell
Kromschröder offers an optional Profibus DP interface
to transfer the activation signals and feedbacks.
BCU 370 · Edition 01.19 5
Application
L1
L1
21
24
23
22
DG
DG
21
24
23
22
DG
DG
BCU 370..I1
9 3
7
min
DL
VG
BCU 370..I1..D3
9 3
7
min
DL
VG
1.1 Applications example
25
28
26
20
19
90° ➔ 0
4
V1
VG..L
DG
DG
VG..L
VG..L
IC 20
11
11
IC 20
DL
4
4
V1
V1
DG
DG
pu/2
pu/2
DL
0 ➔ 90°
5293130 32
V2
M
BVA
0 ➔ 90°
29 3130
5 32
5
V2
V2
M
B VA
GIK
90° ➔ 0
GIK
18
17
13
UVS
25
28
26
20
19
18
17
13
UVS
1.1.1
Modulating-controlled forced
draught burner
The BCU 370 controls the fan and
moves the butterfly valve to prepurge and ignition position. It issues
the enable signal to the control system after start-up of the burner.
Modulating-controlled forced
1.1.2
draught burner with tightness
control
In addition to controlling the forced
draught burner, the burner control
unit also monitors the fail-safe
function of the two solenoid valves
for gas via the gas pressure switch
DG which is set to pu/2.
Parameter 27 = 1: V2 is “ON” during
burner operation.
BCU 370 · Edition 01.19 6
Application
L1
21
24
23
22
DG
DG
BCU 370..D3
9 3
7
min
DL
VG
V1 V2
DL
45
DG
pu/2
11
DG
VG..L
VG
IC 20
BVA
90° ➔ 0
0 ➔ 90°
29 3130
632
V3
M
GIK
1.1.3
25
28
26
20
19
18
17
13
Modulating-controlled forced draught burner with pilot burner and tightness control
A pilot burner ignites the main burner and is switched off during the
main burner’s safety time.
Parameter 27 = 0: V2 is “OFF”, i.e. interrupted pilot burner, during burner
operation.
UVS
BCU 370 · Edition 01.19 7
Application
L1,
PLC
BCU 370..B1
ϑ
L1,
L1,
PLC
Profibus DP
BCU 370..B1-3
ϑ
L1,
0 ➔ 90°
29 31 3230
M
3PS
29 30 31
BUS
90° ➔ 0
BUS
0 ➔ 90°
Profibus DP
Temperature
controller
90° ➔ 0
25
28
26
32
3PS
Temperature
controller
ϑ
1.1.4 Controlling the BCU via PROFIBUS DP
The BCU 370..B1 issues the enable
signal to the temperature controller
for capacity control. The temperature controller then controls the
butterfly valve directly.
ϑ
1.1.5 Controlling the BCU and the
butterfly valve via PROFIBUS DP
The BCU 370..B13 receives posi-
tioning information for the butterfly
valve from the temperature controller via the PROFIBUS DP and activates the butterfly valve following
controller enable.
M
BCU 370 · Edition 01.19 8
Certification
2 Certification
Certificates – see ww w.docuthek.com
EU certified pursuant to
Directive:
– Low Voltage Directive (2014/35/EU),
– EMC Directive (2014/30/EU).
Regulation:
– Gas Appliances Regulation (EU) 2016/426
FM approved
Factory Mutual Research Class: 7611 “Combustion
Safeguards and Flame Sensing Systems”. Suitable for
applications pursuant to NFPA 86.
www.approvalguide.com
ANSI/CSA approved
UL listed
USA and Canada
Underwriters Laboratories – UL 372 “Primary Safety
Controls for Gas and Oil-fired Appliances”.
ww w.ul.com ➔ Tools (at the bottom of the page) ➔ Online Certifications Directory
AGA approved
AGA
Australian Gas Association, Approval No.: 6880
http://ww w.aga.asn.au/product _directory
Eurasian Customs Union
The product BCU 370 meets the technical specifica-
tions of the Eurasian Customs Union.
American National Standards Institute/Canadian
Standards Association – Class number: 333501 and
333581.
BCU 370 · Edition 01.19 9
Function
BCU 370..I1
F1
F3
l v1 v2s1v3 cc
31 2 4 5 6 7 8 9 10 11 12 13 14 15 16 1917 18 20 21 22 23 24 25 26 27 28 29 30 31 32
V1 C S1 S L A Z M V2 V3 R
C
V1
V2
DL DG
V3
ppp
minDGmax
230V~
PE N
Z
I
3 Function
3.1 Connection diagrams
3.1.1 BCU 370
The drawing shows the BCU 370..I1 with integrated
ignition unit, ionization control and double-electrode
operation.
For cable selection and wiring, see page 66 (Project
planning information).
90° ➔ 0
0 ➔ 90°
r
r1 s
max. 1 A,
max. 1 A,
253 V
253 V
M
3PS
ϑ
For the explanation of symbols, see page 77 (Legend).
▼
L1 (L1)
N (L2)
PE
BCU 370 · Edition 01.19 10
Function
13 14 15 16 PE
3
2
UVS
1
BCU 370..I1 for 120 V and 230 V, UV control
BCU 370..I2
N13 14 15 16 PE
3
2
UVS
1
Z Z
BCU 370..I2 for 230 V, ignition by electrode to electrode
BCU 370..I3 for 120 V, ignition by electrode to electrode
BCU 370..I3
N13 14 15 16 PE
with centre tap for secondary grounding
▼
3
2
UVS
1
BCU 370 · Edition 01.19 11
Z Z
Function
BCU 370
BCU 370
BCU 370 with external ignition transformer, e.g. TZI or
N13 14 15 16 PE
Z
I
TGI
BCU 370 with single-electrode operation, which requires an external ignition transformer TZI or TGI
N13 14 15 16 PE
BCU 370..D3, gas pressure switch DG for tightness
BCU 370..D3
11 12
control
▼
p
e
p
2
DG
BCU 370 · Edition 01.19 12
Function
BCU 370..U1
131141516 PE N
4
3
UVC 1
2
1
BCU 370..U1 with UV flame detector UVC 1 for continuous operation
Use 5-core connection cable including a PE wire and
complying with local regulations.
The UVC 1 is grounded using a PE wire connection
which is galvanically connected to the housing.
BCU 370 · Edition 01.19 13
Function
BCU 370
90° ➔ 0
0 ➔ 90°
r
25 26 27 28 29 30 31 32
3PS
0
90°
16
3.1.2 BCU 370 with actuator IC 20
The “closed contact” (90° ➔ 0) of the external three-
point step controller (3PS) can be connected to terminal 26 or 27.
Terminal 26: the controller operates between the open
and ignition positions.
Terminal 27: the controller operates between the open
and closed positions.
L1 (L1)
N (L2)
PE
90° ➔ 0
0 ➔ 90°
321
674812 1115 13
S11
PE
IC 20
S10
S1S2
S3 S4
M
BCU 370 · Edition 01.19 14
Function
90° ➔ 0
0 ➔ 90°
r
25 26 27 28 29 30 31 32
3.1.3 Capacity control by adjusting the valve between the Open position and a separate Min position
This connection is used if the valve position to be ap-
proached is below the Ignition position.
Standard wiring of BCU 370 and BCU 370..B1 without
three-point step control function
Valve position Activation of terminal
Upper end position Open 28
Lower end position Closed 27
Lower end position Min Via separate limit switch
Lower end position Ignition 26
–+
3PS
BCU 370 · Edition 01.19 15
M
Min
Function
BCU 370..I1..B1
F1
F3
l v1 v2s1v3 cc
31 2 4 5 6 7 8 9 10 11 12 13 14 15 16 24 25 26 27 28 29 30 31 32
V1 C S1 S L A Z M V2 V3 R
C
V1
V2
DL DG
V3
ppp
minDGmax
r
230V~
PE N
Z
I
3PS
BCU 370..B1
ON
OFF
2B 2A 1B 1A
0 ➔ 90°
M
90° ➔ 0
L1 (L1)
N (L2)
PE
PROFIBUS-DP
3.1.4 BCU 370..B1 with PROFIBUS DP
Function, see page 32 (PROFIBUS DP)
For cable selection and wiring, see page 66 (Project
planning information).
For the explanation of symbols, see page 77 (Legend).
BCU 370 · Edition 01.19 16
Function
3.1.5 Assignment of connection terminals
Terminal Type Designation Function
1, 2 V AC input Supply voltage
3 V AC output Fan Connection for fan control
4
5 Gas valve V2 Connection of phase for gas valve V2
6 Gas valve V3 Connection of phase for gas valve V3
7
9 Minimum gas pressure Connection for pressure switch to monitor the minimum gas pressure
11 Maximum gas pressure Connection for pressure switch to monitor the maximum gas pressure
8, 10 and
12
Safety circuit
output
Inputs for
pressure switches
V AC outputs Mains supply Phase for pressure switch mains supply
13
14 Supply voltage to UV sensor Output for supply voltage to UV sensor
15 Burner ground Burner ground input for UV sensor
Flame control
Gas valve V1 Connection of phase for gas valve V1
Minimum air pressure Connection for pressure switch to monitor the minimum air pressure
Flame amplifier input Input for flame amplifier
16 Ignition transformer output Output for (external) ignition transformer
17, 18
19, 20
1) 2)
21
1) 2)
22
1) 2)
23
1) 2)
Floating contact
1) 2)
V AC input
Signalling contact for operating
signals
Signalling contact for faults Contact between terminals 19 and 20 closes in the event of a BCU fault signal
Start-up signal Signal applied: BCU start; no signal: BCU stop
Controlled air flow
Remote reset Input for external signal (button) to reset the unit af ter a fault lock-out
24 Controller enable/emergency stop Connection for higher-level safety devices and interlocks (e.g. emergency stop)
25
26
27
28
2)
2)
2)
2)
Connection for
external threepoint step
controller
Controller enable
Y (to ignition position) Connection for the signal to activate the ignition position
Y (to min. position) Connection for the signal to activate the position for minimum capacity
Y+ (to max. position) Connection for the signal to activate the position for maximum capacity
Voltage to operate the BCU,
1 = phase (L1), 2 = neutral conductor (N)
Contact between terminals 17 and 18 closes once the operating signal has been
received from the burner
Signal applied: fan is started to supply air to the combustion chamber for cooling, for
example. Only functional in standby. The function is deactivated as soon as a signal is
received at terminal 1 (BCU star t).
Output signal for controller enable for the three-point step controller. The actuator can
be set to various positions.
▼
BCU 370 · Edition 01.19 17
Function
Terminal Type Designation Function
29, 30
and 31
32 Safety circuit input
1)
BCU..B1: not fitted/non-functional
2)
BCU..B13: not fitted/non-functional
V AC output Capacity control Connection for capacity control using an actuator
Feedback from actuator/
frequency converter
Connection for the position feedback signal from the actuator
BCU 370 · Edition 01.19 18
Function
3.2 BCU 370 program sequence
Switch on BCU 370
In the event of fault signal: reset
00
H0
H0
01
A1
P1
A2
03
04
05
Start-up position/standby
Start-up with ϑ signal
Switch-on delay time t
Fan run up time t
Butterfly valve moves to Open position
Pre-purge time t
Butterfly valve moves to Ignition position
Pre-ignition time t
Ignition activated
Safety time t
burner/pilot burner (P12),
Flame proving period t
running for burner/pilot burner (P13)
PV
SA1
V1 and V2 open
running (P22)
E
(P20)
GV
running (P18)
running (P21)
VZ
running for
FS1
3.2.1 Normal start-up
If a fault from the preceding operating cycle is still being signalled after
switching on, it will be necessary
to reset this first. Once the startup signal (ϑ) has been applied, the
switch-on delay tE starts to elapse.
During the fan run-up time t
GV
which follows, the fan starts with
the butterfly valve being closed. The
butterfly valve then moves from the
Closed to the Open position. After
pre-purge, it moves back to the Ignition position.
The running times depend on the
respective actuator. The BCU waits
for actuator feedback before continuing the program sequence.
Now the BCU activates pre-ignition
t
and then opens valves V1 and
VZ
V2 for the pilot burner. The ignition
time tZ is constant.
After the flame proving period for
the pilot burner t
to ignite the main burner.
, valve V3 opens
FS1
▼
BCU 370 · Edition 01.19 19
04
05
03
Flame proving period t
FS1
running for burner/pilot burner (P13)
Safety time t
SA1
running for
burner/pilot burner (P12),
V1 and V2 open
Pre-ignition time t
VZ
running (P21)
Ignition activated
Function
06
07
H8
08
08
P9
A0
Safety time t
Controller enabler signal delay time t
Butterfly valve moves to Closed position
SA2
If parameter P27 = 0:
V2 is switched off
Flame proving period t
running for main burner (P15)
Controller enable signal
Controlled shut-down
Post-purge time t
running for main burner (P14),
V3 opens
FS2
(P29)
RF
via ϑ signal
running (P19)
PN
If parameter 27 = 0, V2 closes at the
end of the main burner safety time
t
. The pilot burner is switched off.
SA2
Then the flame proving period for
the main burner t
and the con-
FS2
troller enable signal delay time tRF
start to elapse. Af terwards, the BCU
issues the enable signal to the controller.
If there is no pilot burner, program
steps
06
and
07
will be omitted.
As soon as the start-up signal (ϑ) is
switched off, post-purge starts. The
butterfly valve moves to the Ignition position during this time, then
to the Closed position. Next, the
BCU rests in the start-up position/
standby.
00
BCU 370 · Edition 01.19 20
Start-up position/standby
Function
00
H0
H0
01
02
03
04
05
06
Start-up position/standby
Start-up with ϑ signal
Switch-on delay time t
Fan run up time tGV (P20)
Waiting time t
Pre-ignition time t
Ignition activated
Safety time t
burner/pilot burner (P12),
V1 and V2 open
Flame proving period t
running for burner/pilot burner (P13)
Safety time t
running for main burner (P14),
SA2
V3 opens
running (P22)
E
running (P21)
VZ
running for
SA1
3.2.2 Quick start, butterfly valve
waits in the Ignition position
Parameter 06 = 0, parameter 28 = 0
Quick start is the same as normal
start, except that pre-purge is
dispensed with. The burner starts
quicker. This results in improved
control quality, since there is no
dead time, the energy is used better
and no cold air is fed to the combustion chamber.
The BCU 370 only carries out a
W
quick start if the last shut-down
was a controlled shut-down. No
more than 24 hours may have
elapsed and the BCU must have
been switched on.
In contrast to the “normal start-up”,
in the case of a quick start, program
A1
FS1
steps
ted.
P1
,
and
A2
will be omit-
If there is no pilot burner, program
steps
06
und
07
will also be omit-
ted.
If parameter P27 = 0:
V2 is switched off
BCU 370 · Edition 01.19 21
▼
05
06
04
03
Flame proving period t
FS1
running for burner/pilot burner (P13)
Safety time t
SA2
running for main burner (P14),
V3 opens
If parameter P27 = 0:
V2 is switched off
Safety time t
SA1
running for
burner/pilot burner (P12),
V1 and V2 open
Pre-ignition time t
VZ
running (P21)
Ignition activated
Function
07
H8
08
Controller enabler signal delay time t
Flame proving period t
running for main burner (P15)
Controller enable signal
After controlled shut-down, the
post-purge time tPN starts to elapse
FS2
and then the butterfly valve moves
to the Ignition position in preparation for the next start.
(P29)
RF
NOTE: Quick start is not allowed for
units with FM or CSA approval.
08
P9
A1
A2
00
BCU 370 · Edition 01.19 22
Butterfly valve moves to Open position
Butterfly valve moves to Ignition position
Controlled shut-down
via ϑ signal
Post-purge time t
Start-up position/standby
PN
running (P19)
Function
00
H0
H0
A1
A2
01
02
03
04
05
Start-up position/standby
Start-up with ϑ signal
Switch-on delay time tE running (P22)
Butterfly valve moves to Open position
Butterfly valve moves to Ignition position
Fan run up time t
Waiting time t
Pre-ignition time t
Ignition activated
Safety time t
for burner/pilot burner (P12),
V1 and V2 open
Flame proving period t
running for burner/pilot burner (P13)
(P20)
GV
W
running (P21)
VZ
running
SA1
FS1
3.2.3 Quick start, butterfly valve
waits in the Closed position
Parameter 06 = 0, parameter 28 = 1
Pre-purge will also be omitted for
this type of quick start. To prevent
cold air from entering the combustion chamber while the BCU is in
start-up position/standby, the butterfly valve waits in the Closed position.
The BCU 370 only carries out a
quick start if the last shut-down
was a controlled shut-down. No
more than 24 hours may have
elapsed and the BCU must have
been switched on.
After the switch-on delay time t
,
E
the butterfly valve moves to the Ignition position. The Ignition position
is always approached from the top.
Therefore, the butterfly valve moves
to the Open position first.
▼
BCU 370 · Edition 01.19 23
05
04
03
Flame proving period t
FS1
running for burner/pilot burner (P13)
Safety time t
SA1
running
for burner/pilot burner (P12),
V1 and V2 open
Pre-ignition time t
VZ
running (P21)
Ignition activated
Function
06
07
H8
08
08
P9
Safety time t
Controller enabler signal delay time t
Post-purge time t
SA2
If parameter P27 = 0:
V2 is switched off
Flame proving period t
running for main burner (P15)
Controller enable signal
Controlled shut-down
running for main burner (P14),
V3 opens
FS2
(P29)
RF
via ϑ signal
running (P19)
PN
If there is no pilot burner, program
steps
06
and
07
will be omitted.
As soon as the start-up signal (ϑ) is
switched off, post-purge starts. The
butterfly valve moves to the Ignition position during this time, then
to the Closed position. Next, the
BCU rests in the start-up position/
standby.
NOTE: Quick start is not allowed for
units with FM or CSA approval.
A0
00
BCU 370 · Edition 01.19 24
Butterfly valve moves to Closed position
Start-up position/standby
Function
00
H0
H0
A1
A2
01
02
03
04
05
Switch on BCU 370
In the event of fault signal: reset
Start-up position/standby
Start-up with ϑ signal
Switch-on delay time t
Butterfly valve moves to Open position
Butterfly valve moves to Ignition position
Fan run up time t
Waiting time t
Pre-ignition time t
Ignition activated
Safety time t
burner/pilot burner (P12),
V1 and V2 open
Flame proving period t
running for burner/pilot burner (P13)
running (P22)
E
GV
W
running (P21d
VZ
running for
SA1
(P20)
FS1
3.2.4 Start-up without pre-purge,
butterfly valve waits in the Closed
position
Parameter 18 = 0, parameter 28 = 1
If a fault from the preceding operating cycle is still being signalled after
switching on, it will be necessary
to reset this first. Once the startup signal (ϑ) has been applied, the
switch-on delay t
starts to elapse.
E
Afterwards, the butterfly valve
moves from the Closed to the Open
position and then to the Ignition position. During the fan run-up time
t
which follows, the fan starts
GV
with the butterfly valve being set to
Ignition position.
After the waiting time t
, the BCU
W
activates pre-ignition tVZ and then
opens valves V1 and V2 for the
pilot burner. The ignition time tZ is
constant. After the flame proving
period for the pilot burner t
FS1
, valve
V3 opens to ignite the main burner.
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BCU 370 · Edition 01.19 25
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