5.6.4Resistance check of the temperature sensor with integrated overheating protection 510
5.6.5Fan and combustion air intake line visual inspection 512
5.6.6Burner motor inspection 512
5.6.7Electronic ignition unit inspection 513
5.6.8Ignition electrode inspection 514
5.6.9Flameguard inspection 514
5.6.10Fuel pump inspection 515
5.6.11Solenoid valve inspection 516
5.6.12Nozzle block preheater inspection 517
5.6.13Circulating pump inspection 518
6Wiring diagrams
6.1General 601
7Servicing
7.1General 701
7.1.1Heater servicing 701
7.2Servicing 701
7.2.1Periodic heater maintenance 701
7.2.2CO2 content adjustment 701
8Burner head, components and heater removal and installation
8.1General 801
8.2Burner head removal and installation 802
8.3Removal and installation of the temperature sensor with integrated overheating protection 803
8.4Hood removal and installation 803
8.5Fan wheel removal and installation 803
8.6Electronic ignition unit and ignition electrode removal and installation 804
8.7Control device removal and installation 805
8.8Fuel pump removal and installation 805
8.9Solenoid valve removal and installation 807
8.10Nozzle block preheater removal and installation 808
8.11Fuel nozzle removal and installation 809
8.12Combustion chamber removal and installation 809
8.13Heat exchanger removal and installation 810
8.14Heater removal and installation 810
8.15Start-up after burner head or heater installation 811
8.15.1Bleeding the fuel system 811
8.15.2Bleeding of the coolant circuit 811
9Modifications and retrofits
9.1General 901
2
Thermo plus 230/300/350Content
10Packing/storage/shipping
10.1General 1001
Appendix
Periodic heater maintenance A-1
3
Thermo plus 230/300/3501Introduction
Danger to life and health!
Warning!
Hazardous to health!
Caution!
Danger to life and health!
Warning!
1Introduction
1.1Content and purpose
This workshop manual is used during maintenance and
repair of water heaters (further referred to as heaters)
Thermo plus 230, plus 300 and plus 350.
ATTENTION:
Work on the heater may only be performed by briefed
and/or trained by Spheros personnel.
1.2Effectivity of the workshop manual
The workshop manual applies to heaters listed on the title
page of this document.
It may be subjected to modifications and amendments.
The respectively currently effectife version is binding. This
version can be found on the Spheros homepage under
Service/Downloads/Heating systems.
1.3Meaning of highlighted content
1.4Symbols
Symbol tightening torque value:
Identifies in graphics parts (eg nuts, bolts)
that are to be mounted with a specific tightening torque. The torque values are shown
at the symbol and are binding.
1.5Further documentation to be used
The use of additional service literature is required.
References are provided in the workshop manual at
appropriate locations.
Use the following documents during operation and maintenance of the heaters:
•Operating and Service Instructions
•Installation Instructions
•Technical Information (TI)
•Spare Parts List
•Operating Instructions for the Spheros Thermo Test,
further referred to as STT Diagnosis
Throughout this manual the emphasized words Warning!,
Caution!, ATTENTION: and NOTE: used as follows:
This caption is used to indicate possible severe injuries or fatal accidents if instructions or procedures
are carried out incorrectly or entirely disregarded.
This caption is used to indicate possible minor injuries if instructions or procedures are carried out
incorrectly or entirely disregarded.
ATTENTION:
This caption points to actions which may cause material damage.
NOTE:
This caption is used to draw attention to an important
feature.
1.6Safety information and regulations
Basically, general accident pevention provisions and the
valid industrial safety directions must be adhered to.
"General Safety Regulations" which exceed the framework of these provisions are listed below. The specific
safety regulations which affect the present manual are
issued highlighted in the individual sections or procedures.
1.6.1 General safety regulations
Read the Thermo plus Operating and Service Instructions before operating the heater for first time.
Familiarize yourself with the Thermo plus Installation
Instructions before you make any modifications to the
existing heater installation.
NOTE:
The Thermo plus Operating and Service Instructions
contain safety instructions and regulations to be followed
for safe operation of the heater.
The Thermo plus Installation Instructions contain the
statutory regulations and other safety hints and regulations for the proper installation of the heater.
101
Thermo plus 230/300/3501Introduction
STOP!
1.6.2 Other safety information
1.6.2.1 Temperature sensors
ATTENTION:
The temperature sensors cable may not be mechanically stressed (pull on the cable, carry the heater at
the cable etc.).
1.7Suggestions for improvement and
change
Please direct any complaints, improvement or modification suggestions regarding this manual to:
service@spheros.de
102
Thermo plus 230/300/3502Technical Data
2Technical Data
Unless limiting values are defined, the technical data
should be understood with tolerances of ±10% common
for heaters at an ambient temperature of +20°C, and at
nominal voltage.
Table 201 Technical Data
HeaterThermo plus 230Thermo plus 300Thermo plus 350
ECE Type Approval Number E1 122R 00
Kind of construction
Heating flow (at ambient temperature of
20°C)
Fuel
Fuel consumptionkg/h
Rated voltageV =
Operating voltage rangeV =
Rated power consumption at 24V *W
Max. permitted temperature of sucked
combustion air at < 85°C ambient temperature
Max. permitted temperature of sucked
combustion air at > 85°C ambient temperature
Permitted ambient temperature during operation
Permitted storage temperature°C
Permitted operating overpressurebar
Capacity of the heat exchangerl
Minimum water flow ***l/h
Minimum capacity of the water systeml
CO
in exhaust gas at rated voltageVol %
2
Heater dimensions (tolerance ± 3 mm)mm
Weightkg
kW
(kcal/h)
°C
°C
°C
046604670468
High pressure atomizer
23
(20 000)
Diesel / Heating oil
2.53.03.6
6090120
-40...+ 85 (100**)
190024002700
9.0 + 1.5
Length 540 / Width 250 / Height 222
30
(26 000)
24
20.5 ... 30
85
60
-40...+ 110
max. 2.0
1.8
25
9.5 + 1.59.5 + 1.5
16.8
(30 000)
35
* without circulating pump
** When operating in ambient temperatures >85°C a special Spheros wiring harness is to be used.
** Minimum water flow at coolant temperatures above 50°C
Below 50°C a lower water flow is permitted, if the occurence of vapor bubbles due to local overheating safely can be excluded.
2.1Elektrical components
Control unit, circulating pump, solenoid valve, electronic
ignition and the digital timer are designed for 24V nominal
voltage. The burner motor supply voltage is controlled by
the control device.
NOTE:
2.2Fuel
Suitable fuel is the diesel fuel specified by the vehicle manufacturer. Only the on the model plate of the heater
specified fuel must be used.
The following table lists the by Spheros approved fuels
and their specifications.
Circulating pumps must be assigned to the heaters
according to the flow resistance in the coolant circulation
system.
201
Thermo plus 230/300/3502Technical Data
FuelRequirements
acc.
Summer dieselDIN EN 590
Winter dieselDIN EN 590
Arctic diesel and Diesel for a strong
winter climate
Bio diesel (FAME)
Paraffinic diesel fuel from synthesis
or hydrogenation (HVO)
Further information on approved fuels contains the TI
*
(Technical Information) Fuels.
It can be found on the Spheros homepage under Service/Technical Updates/Heating systems.
In case of air temperatures below 0°C a commercial available winter Diesel fuel must be used.
The usage of flow improvers respectively additives is permitted. There are no negative influences due to additives
known.
While using the fuels, their operating limits must be
considered and if necessary, suitable measures
(nozzle preheating, electrical heated filter) should be
applied.
If fuel is supplied from the vehicle tank, follow the
vehicle manufacturer’s instructions on additives.
The heaters Spheros Thermo plus 230, plus 300 and
plus 350 are used in conjunction with the vehicle heating
system
–to heat the passenger compartment
–to defrost the windows
–to preheat water-cooled vehicle engines.
The water heater operates independently from the vehicle
engine and is connected to the cooling system, the fuel
system and the electrical system of the vehicle. It is bolted
down to the vehicle chassis or is secured using an additional cross beam.
Heat is generated by combustion of liquid fuels. Via the
heat exchanger of the heater, the heat is dissipated to a
coolant circuit. The adaptation to the changing demand of
heat is reached by intermittent operation (intermittend
mode).
The control device controls on the basis of the signals of
a temperature sensor the on and off switching of the
burner.
Fig. 301 Heater overview
301
Thermo plus 230/300/3503Assemblies and components
Fan wheel
Burner motor
(displayed transparently)
The heaters of the Thermo plus series basically consist of
the main components:
•burner head
•combustion chamber
•heat exchanger
External in the vehicle a circulation pump is installed or in
case of compact device directly on the heater.
3.1Burner head
The burner head consists of the components
•combustion air fan
•control device with burner motor and flame guard
•fuel pump with solenoid valve and atomizer nozzle
•electronic ignition unit with ignition electrodes
•nozzle preheater (optional)
•disc with sight window
3.1.1 Combustion air fan
The combustion air fan (Fig. 302) transports the air
required for combustion from the combustion air intake to
the combustion chamber.
The combustion air fan consists of the burner motor at the
control device and the fan wheel. Air is drawn in through
the air intake opening in the hood.
This air intake opening is equipped with a splashguard, a
protective grid or an intake air elbow (see Fig. 301).
3.1.2 Control device
The control device (Fig. 303) ensures the operating
sequence and burner operation monitoring. It constitutes
a unit with the burner motor.
The control device is mounted onto the front of the burner
housing, under the hood. It protrudes with four external
electric ports out the heater:
•Port C - power/control,
•Port P - circulating pump,
•Port T - temperature sensors and
•Port G - diagnosis interface
Internally the control device provides the ports
•connector V - nozzle preheater,
•connector M - solenoid valve, and
•connector Z - electronic ignition unit.
3.1.2.1 Burner motor
The control device constitutes a unit with the brushless
EC burner motor which is installed at the burner housing.
This arangement allows its direct power supply via the
control device board. The speed measurement is done by
a Hall sensor module.
The shaft of the external rotor motor protrudes through the
control device. To the forward end the fan wheel is installed and on the backside of the control device via a coupling the fuel pump is driven.
The speed of the burner motor is controlled depending on
the operating status by the control device.
Fig. 302 Combustion air fan
302
Thermo plus 230/300/3503Assemblies and components
Flameguard
Motor shaft
burner motor
Heat transition
Port C
power supply
Port Z
electronic
Port M
solenoid
Port P
circulating pump
Diagnostic
Interface
Port T
temperature
sensors
Burner motor
ignition unit
valve
Model plate with Id.no.
control device/motor
Port G
Diagnosis
Port V
nozzle block
preheating
Ground terminal
to housing
surfaces to
housing
3.1.2.2 Flameguard
The flameguard (see Fig. 304) is integrated in the control
device.
The flameguard monitors the combustion flame condition
during heater operation.
The flame guard is a photo transistor that changes its
resistance depending on the incident light.
Fig. 303 Control device SG1589
303
Thermo plus 230/300/3503Assemblies and components
Disc
Sight window
Flameguard
Fuel pump
Solenoid valve
Screen
O-ring
Burner head
Fig. 304 Flameguard
3.1.3 Fuel pump
The fuel pump is responsible for fuel supply. (Fig. 305).
The pump is driven by the burner motor via a coupling.
Fuel is compressed in the fuel pump to approx. 10 bar and
atomized by the atomiser nozzle.
The solenoid valve installed at the fuel pump opens and
closes the fuel supply to the atomizer nozzle.
For all three heating capacity classes the same fuel pump
is installed.
Fig. 305 Fuel pump with solenoid valve
304
Thermo plus 230/300/3503Assemblies and components
Ignition electrodes
Burner head
Electronic ignition unit
The fuel pump can be used in dual-line operation only
(fuel supply and return line).
If the heater is operated with
–a long fuel supply line
–check valves in the fuel supply and return line
–a fuel filter in the fuel supply line
the fuel supply line must be filled prior to first heater startup (see 8.15).
3.1.4 Electronic ignition unit with ignition
electrodes
The electronic ignition unit (Fig. 306) induces the high
voltage required for ignition of the fuel-air mixture. Ignition
is triggered by a high voltage spark, which is initiated on
the ignition electrodes.
3.1.5 Nozzle block preheater
In case of very low temperatures fuel may exhibit severely
modified viscosity. Due to insufficient fuel atomization
functional heater malfunctions may occur.
Depending on the fuel used, these temperatures vary.
When used in cold regions or if fuels different from diesel
fuel are used, we recommend the use of a nozzle block
preheater (Fig. 307).
The nozzle block preheater consists of a heating element
and a thermostat. It is supplied with electricity via the fuse
of the circulating pump and works only when the circulating pump output is error-free.
At a temperature of < 5°C the heating element heats the
nozzle holder and thus, fuel and atomizer nozzle. Fuel
viscosity is reduced and atomization improved.
The heating time depends on the temperature of intake air
and the heat reflection from the combustion space. Above
8 °C the thermostat switches off. The control device
defines the preheating time depending on the temperature when starting.
The use of the nozzle block preheater is optional. The
retrofitting can be done without control device modification.
NOTE:
The nozzle block preheater is supplied with electricity via
the fuse of the circulating pump and works only when the
circulating pump output is error-free.
3.1.6 Temperature sensors with water
temperature sensor and integrated
overheating protection
The water temperature sensor (Fig. 308) captures the
coolant temperature at the heat exchanger outlet as
electrical resistance.
This signal is transmitted to the control device, where it is
processed.
The overheating protection integrated into the temperature sensor is responsible for temperature limitation.
Overheating protection prevents inadmissibly high heater
operating temperatures.
At a temperature greater than 135°C heater deactivation
and interlocking is initiated.
Fig. 306 Electronic ignition unit with ignition electrodes
305
Thermo plus 230/300/3503Assemblies and components
Thermostat
Heating element
Burner head
NOTE:
The disc is displayed
transparently.
Retaining clamp
Water temperature sensor
with integrated overheat
protection
Fig. 307 Nozzle block preheater
Fig. 308 Temperature sensors
306
Thermo plus 230/300/3503Assemblies and components
Coolant inlet
Coolant outlet
Exhaust outlet
Combustion chamber
Welding seam
Swirl plate
3.2Heat exchanger
The heat exchanger (Fig. 309) transfers the heat generated by combustion to the coolant circulation system.
Depending on the system integration a heat exchanger
with or without thread in the coolant inlet socket can be
installed.
NOTE:
In the heaters are used different combustion chambers
depending on the heating capacity class.
Fig. 311 Combustion chamber
Fig. 309 Heat exchanger
3.3Combustion chamber
The combustion chamber (Fig. 311) is used for generation
and combustion of the fuel air mixture. The generated
exhaust gas heats the coolant flowing through the heat
exchanger.
3.4Circulating pump
The externally arranged circulating pump ensures coolant
transport within the vehicle and/or heater circulation
system.
Depending on the application, the circulating pump is switched on via the control device or directly via the vehicle
electrical system and operated during the entire heater
operation duration.
Further information on the installation and operation of the
circulating pump is contained in the Thermo plus Installation Instructions.
All service information regarding your Spheros circulating
pump(s) can be found under www.spheros.eu/products/
pumps.html.
3.5Fuel filter
As an option a heated fuel filter is available (see
www.spheros.eu/service/spare parts and accessories).
The integrated filter heating is switched on at a fuel temperature of ≤ 0.5 ± 2.5 °C and off at ≥ 5.5 ± 2.5 °C by a
temperature switch.
When the heater is operated at low temperatures,
depending on fuel used a heated fuel filter must be
installed. See TI.
Fig. 310
307
Thermo plus 230/300/3504Heater functions
4Heater functions
4.1General heater functionality
description
The heater principle is based on a high-pressure atomizer
burner and is monitored by an integrated control unit.
The burner motor powers the fan and the fuel pump. The
fuel pump is coupled to the motor using a plastic coupling.
The fan produces the required combustion air, the combustion air volume is impacted by the burner motor speed.
The speed is read and monitored by a Hall sensor.
The speed required for the CO
during first calibration at Spheros and is stored in the
control unit.
In a maintenance event the workshop can adjust the CO
setting using the STT diagnosis (Spheros-Thermo-TestDiagnosis) (siehe 4.3).
The fuel pressure is generated in the fuel pump and
reduced to the required pressure using a pressure limiting
valve.
A solenoid valve releases the fuel via the atomizer nozzle
for combustion in the combustion chamber.
As an option, the fuel pump can be equipped with a nozzle
block preheater. The nozzle block preheater heats the
content is determined
2
nozzle holder with the atomizer nozzle at low temperatures, and thus the fuel. The fuel air mixture is ignited in
the combustion chamber via a high-voltage ignition spark.
The flame is monitored by a flame detector integrated into
the control device.
Depending on the equipment, the heater is switched on
and off using a
•digital timer
•switch
•or climate control.
During heating operation the burner is automatically switched on and off. For control a temperature sensor is
installed in the coolant outlet of the heat exchanger.
The heater is switched on, when the temperature falls
short of a lower temperature threshold, and is switched
off, if the upper temperature threshold is reached (see
2
Table 401).
The switching thresholds depend on the operation mode
of the heater and are programmed into the control device.
An operation indicator is available for monitoring the
operation status of the heater. A flame indication can be
optionally installed.
The operation indicator is also used to output error
messages via flash code.
Table 401 Water Temperature Control Thresholds (standard data set)
HeaterAux. heating
(terminal 61)
onoff (CI)onoff (CI)onoff (CI)
Thermo plus 230
Thermo plus 300
Thermo plus 350
CI: Control idle
on/off :lower/upper threshold
Aux. heating:Heater is operating, engine is opera-
ting
Parking heating: Heater is operating, engine is off
Economy setting: Control temperature is on a lower level
NOTE:
Auxiliary heating has priority over the economy setting!
Time in s0..128 12 1 15...30 900..128 12 1 15...30 900..128 12 1 15...30 90
Status
Look for
Nozzle block preheater
Initial cycle with light check
Pre-ignition
Ignition
Purge cycle 1 with safety period
Purge cycle 2
Nozzle block preheater
Initial cycle with light check
Pre-ignition
Ignition
Purge cycle 1 with safety period
Purge cycle 2
Nozzle block preheater
Initial cycle with light check
Pre-ignition
Ignition
Purge cycle 1 with safety period
Purge cycle 2
OFFStandbyStartHeating Purge
cycle
StandbyStartHeatin g Purge
cycle
StandbyStartH eating Purge
cycle
OFF
Parking heatingAux. heatingParking heating
OnOn or Off
4.2Operational heater sequence
Fig. 401 Operational sequence
4.2.1 Switching on and start
With optional nozzle block preheater:
With activated circulating pump the bimetal at the nozzle
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
When switched on, the operating display is illuminated,
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-voltage 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.
block preheater controls its operation. When the ambient
temperature is less than 5 °C it is turned on. Not timedependent and not limited.
Starting from a temperature <5 °C, the duration of the
nozzle block preheating is prolonged, depending on the
determined temperature. The maximum duty cycle is
limited to 140 seconds. The further procedure is as
described.
4.2.2 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.
402
Thermo plus 230/300/3504Heater functions
The purge cycle ends approx. after 120 seconds. The
combustion air fan is switched off.
The heater is in a controlled break.
The operation indicator is on.
Once the temperature falls short of the lower switching
threshold, the heater restarts burner operation. It runs
through the same sequence as the switching-on
sequence.
4.2.2.1 Auxiliary heating mode and parking heating
mode
From the terminal D+/+61 the control device receives the
information either the vehicle engine is running or not.
If the engine is running the heater is in the auxiliary
heating mode.
The switching thresholds are higher than in the parking
mode with the engine not running.
In the parking heating operation an economy mode may
be activated.
4.2.2.2 Economy circuit
If the economy circuit is activated (economy mode) the
controlled temperatures inthe heating system are maintained at a low temperature level. The lower and upper
switching threshold are reduced.
Due to lower radiation loss the fuel consumption can be
reduced for a lower heat demand (e.g. warmer mode).
The heater burner output is not reduced.
n auxiliary heating mode (signal from terminal D+/+61)
saving mode is automatically deactivated.
4.2.2.3 Gradient evaluation
always achieved.
In order to achieve the minimum combustion period, the
lower switching threshold is variably adjusted by the
control device.
This process is also called hysteresis adaptation and is
applied in parking heating operation as well as auxiliary
heating operation.
If the combustion period falls short of the minimum
combustion period of 120 seconds, the lower switching
value is lowered by 1K for the following combustion
process. The upper switching threshold remains as is.
This can be repeated until the minimum combustion
period is reached or the lower switching threshold is
reduced by 5K.
A further lowering is not possible.
Following a combustion process, where the required
minimum combustion period was reached, the lower switching threshold is raised in steps of 1 K, max. up to the
initial level.
4.2.3 Switching off
Switching the heater off ends the combustion process.
The operation indicator goes out and and the purge cycle
is initiated.
The solenoid valve closes, the flame expires, the combustion air fan and the circulating pump continue running.
The purge cycle ends approx. after 120 seconds. The
combustion air fan is switched off.
If a malfunction occurs during purge cycle (e.g. flame
detection), the purge cycle may be shorter than 120
seconds.
During purge cycle it is permitted to switch the heater back
on. The burner will restart after a purge cycle time of 30
seconds and subsequent initial cycle time.
In case of low coolant flow or poor coolant circuit venting
the temperature quickly increases in heating operation.
The control device recognises the quick temperature
increase and automatically sets the upper switching threshold to a lower value.
The quicker the temperature increases, the lower the switching threshold for starting the controlled break is set.
In addition, the burner is also switched back on again after
the controlled break at a lower switching threshold.
This prevents residual heat triggering the overheating
protection.
4.2.2.4 Minimum combustion period
NOTE:
Frequent burning time under 120 seconds may result in
soot build and increased smoke formation.
A minimum burner combustion period of 120 second is
targeted.
For ambient and operating conditions this target is not
4.3Diagnosis interface and (Spheros
Thermo Test) STT diagnosis
Heaters of the Thermo S series support diagnosis capabilities. Using the STT diagnosis adapter, STT diagnosis
and a PC, the heaters in a vehicle can be checked.
Information on the hook-up of the heater to the diagnosis
and its usage can be found in the STT Operation Instructions which are supplied with the device.
The Operation Instructions are also available for download on the Sheros homepage in the area Service/
Technical Documents/Accessories.
NOTE:
For protection against moisture and contamination ensure
that the diagnosis interface is sealed using a dummy plug,
if not in use.
403
Thermo plus 230/300/3504Heater functions
4.4Fault lock-out and heater lock-out
A distinction is made between fault lock-out and heater
lock-out.
The lock-outs protect the heater and the surrounding
vehicle assemblies against sequence errors after a failure
or a malfunction of individual heater components.
In a heater lock-out safety-related components are
affected by the failure or malfunction. It may only be
released by Spheros trained personnel after eliminating
the cause.
Each fault lock-out and heater lock-out is stored in the
control device.
4.5Fault lock-out
If one of the malfunctions listed below occurs, the heater
will initiate a fault shut-down, followed by a fault lock-out.
Depending on the error timing, no purge cycle or a 120
seconds purge cycle will be executed.
Flash impulses are outputted via the operation indicator.
In case of several sequential fault lock-outs a heater lockout is initiated (see 5.4).
NOTE:
If the circulating pump is externally actuated it will continue operating, if it is not affected itself.
30 V within a duration of 6 seconds (purge cycle only,
no fault lock-out).
4.5.2 Malfunctions during heater operation
In case of malfunctions during heater operation, a 120
seconds purge cycle will be executed first. Subsequently
the heater status is switched to fault lock-out.
Malfunction criteria:
•Circulating pump - short circuit and/or interruption
•Water temperature greater than the upper switching
threshold
•Temperature sensor delivers unacceptable tempe-
rature values.
•Heater operation outside the permissible temperature
range.
•Burner motor speed signal faulty.
•Flame interruption (combustion interruption for longer
than 15 seconds).
•Voltage falls short of the low voltage threshold of
approx. 20.5 V within a duration of 20 seconds after a
heating request.
•Voltage exceeds the high voltage threshold of approx.
30 V within a duration of 6 seconds (purge cycle is
applied only, but no fault lock-out).
•Control device malfunction
4.5.3 Malfunctions during purge cycle
In case of several sequential fault lock-outs a heater lockout is initiated (see 4.6).
4.5.1 Malfunctions during switching-on and
start procedure
If malfunctions occur during switching-on or during the
start process prior to ignition, the heater will be switched
off without purge cycle.
The heater is in fault lock-out.The motor stops immediately or does not start.