403
Thermo H plus
4 Functions of the heater
Operational heater sequence
4.3.1 Switching on and start
When switched on, the operating display is illuminated,
the control unit starts controlled operation and checks the
coolant temperature.
If the coolant temperature is below the lower temperature
threshold, the initial cycle starts.Combustion air fan and
circulating pump are switched on. The initial cycle is used
to flush the combustion chamber.
In the start phase until to the pre-ignition the in the control
device integrated flameguard must continuously detect
„dark“, otherwise it comes to a fault lock-out and the
heater changes into the standby.
After approx. 12 seconds (initial cycle time) the high-vol-
tage spark is ignited. Approx. 1 second later the solenoid
valve in the fuel pump is opened.
The fuel injected via the atomizer nozzle and mixed with
the air of the combustion air fan, is ignited by the ignition
spark and burned in the combustion chamber.
The monitoring of the flame is done by the flame guard.
A few seconds after a flame is detected, the control device
switches the electronic ignition unit off. Until then the
flame is stabilized and the heater is not yet in heating
mode.
With optional nozzle block preheater:
With activated circulating pump the bimetal at the nozzle
block preheater controls its operation. When the ambient
temperature is less than 5 °C it is turned on. Not time-
dependent and not limited.
Starting from a temperature <5 °C, the duration of the
nozzle block preheating is prolonged, depending on the
determined temperature. The burner motor does not run
during the entire preheating time. It starts at the latest 12
seconds before the expiry of the determined preheating
time with the initial cycle. The time of the initial cycle can
thus be extended to a maximum of 140 seconds.
The further procedure is as described.
4.3.2 Heating operation
After the flame is stabilised, the heater is in controlled
(normal) operation.
Depending on the coolant temperature, the coolant
temperature is maintained at one level by switching the
burner alternately on and off.
Once the upper switching threshold is exceeded, heating
operation is finished and the purge cycle initiated.
The solenoid valve is closed, the flame expires, however
the combustion air fan and the circulating pump continue
running.
Fig. 401 Operational sequence
Signals
Main switch
off
on
off
UPFA
Econ. mode
Terminal 61
off (parking heating)
on (aux. heating)
Coolant temperature
T > T_min
T < T_min
T >= T_max
T >= T_max
Fl
am
e
ge
ne
ra
tio
n
Fl
am
e
ge
ne
ra
tio
n
Fl
am
e
ge
ne
ra
tio
n
Actuators
Operation indicator
Flame indicator
Comb. air motor
Circulating pump
Electronic ignition unit
Solenoid valve
Nozzle block preheater
Time in s
0..128 12 1
15
...
30 90
0..128 12 1
15
...
30 90
0..128 12 1
15
...
30 90
Status
Lo
ok
fo
r
N
oz
zl
e
bl
oc
k
pr
eh
ea
te
r
In
iti
al
c
yc
le
w
ith
li
gh
t c
he
ck
Pr
e-
ig
ni
tio
n
Ig
ni
tio
n
Pu
rg
e
cy
cl
e
1
w
ith
s
af
et
y
pe
rio
d
Pu
rg
e
cy
cl
e
2
N
oz
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e
bl
oc
k
pr
eh
ea
te
r
In
iti
al
c
yc
le
w
ith
li
gh
t c
he
ck
Pr
e-
ig
ni
tio
n
Ig
ni
tio
n
Pu
rg
e
cy
cl
e
1
w
ith
s
af
et
y
pe
rio
d
Pu
rg
e
cy
cl
e
2
N
oz
zl
e
bl
oc
k
pr
eh
ea
te
r
In
iti
al
c
yc
le
w
ith
li
gh
t c
he
ck
Pr
e-
ig
ni
tio
n
Ig
ni
tio
n
Pu
rg
e
cy
cl
e
1
w
ith
s
af
et
y
pe
rio
d
Pu
rg
e
cy
cl
e
2
OFF
Standby
Start
Heating
Purge
cycle
Standby
Start
Heating
Purge
cycle
Standby
Start
Heating
Purge
cycle
OFF
Parking heating
Aux. heating
Parking heating
On
On or Off
Summary of Contents for Thermo H 160
Page 47: ...memos...
