Spheros Thermo S 160 Instruction manual

Water Heater Workshop Manual
Thermo S 160
Thermo S 230
Thermo S 300
Thermo S 350
Thermo S 400
with Control Unit 1586
Status: 12/2011
Ident.-no. 11114913B

Thermo S 160/230/300/350/400 1 Introduction
1
1 Introduction
1.1 Content and purpose 101
1.2 Workshop manual validity 101
1.3 Meaning of highlighted content 101
1.4 Additional applicable documentation 101
1.5 Installation and safety regulations 101
1.5.1 Legal installation regulations 101
1.5.2 Installation regulations for railway vehicles 102
1.5.3 General safety regulations 102
1.5.4 Combustion air supply 105
1.5.5 Exhaust line 105
1.5.6 Adapter wiring harness 105
1.6 Suggestions for Improvement and change 105
2 Technical data
2.1 Electrical components 201
2.2 Fuel 201
3 Assemblies and components descriptions
3.1 Burner 302
3.1.1 Combustion air fan 302
3.1.2 Fuel pump 302
3.1.3 Nozzle block preheater 303
3.1.4 Control unit 303
3.1.5 Electronic ignition unit with ignition electrodes 304
3.1.6 Temperature sensors with water temperature sensor and integrated overheating protection 304
3.2 Heat exchanger 305
3.3 Combustion chamber 306
3.4 Circulating pump 307
3.4.1 Aquavent 5000 (U4814) and Aquavent 5000S (U4854) circulating pumps 307
3.4.2 Aquavent 6000C (U4855) and Aquavent 6000SC (U4856) circulating pumps 308
3.5 Fuel filter 308
4 Heater functions
4.1 General heater functionality description 401
4.2 Operational heater sequence 402
4.2.1 Switching on and start 402
4.2.2 Heating operation 402
4.2.3 Switching off 403
4.3 Diagnosis interface and STT-diagnosis 405
4.3.1 Test plug 405
4.4 Malfunction interlock and heater interlock 406
4.5 Malfunction interlock 406
4.5.1 Malfunctions during switching-on and start procedure 406
4.5.2 Malfunctions during heater operation 406
4.5.3 Malfunctions during run-down 407
4.5.4 Malfunction interlock release and error clearance 407
4.6 Heater interlock 407
4.6.1 Heater interlock release 407
4.7 Error output 408
5 Troubleshooting and error correction
5.1 General 501

1 Introduction Thermo S 160/230/300/350/400
2
5.2 General error symptoms 501
5.3 Malfunction code output via flash code 503
5.4 Error symptoms during functional tests with malfunction code output or diagnosis 505
5.4.1 Error symptom "No start within safety period" 505
5.4.2 Error symptom "Flame interruption" 505
5.4.3 Error symptom "Low voltage" 507
5.4.4 Error symptom "Extraneous light detected prior to ignition or during run-down" 508
5.4.5 Error symptom "Flame detector defective" 509
5.4.6 Error symptoms "Temperature sensor / overheating protection defective" and "Overheating" 509
5.4.7 Error symptom "Circulating pump interruption" 509
5.5 Individual component tests 510
5.5.1 General visual inspection 510
5.5.2 Heat exchanger visual inspection 510
5.5.3 Combustion chamber visual inspection 510
5.5.4 Resistance check of the temperature sensor with integrated overheating protection 511
5.5.5 Adapter wiring harness inspection 512
5.5.6 Fan and combustion air intake line visual inspection 512
5.5.7 Burner motor inspection 512
5.5.8 Electronic ignition unit inspection 513
5.5.9 Ignition electrode inspection 514
5.5.10 Flame detector inspection 515
5.5.11 Fuel pump inspection 516
5.5.12 Solenoid valve inspection 517
5.5.13 Nozzle block preheater inspection 518
5.5.14 Circulating pump inspection 519
6 Schematic diagrams
6.1 General 601
7 Servicing
7.1 General 701
7.1.1 Heater servicing 701
7.2 Servicing 701
7.2.1 CO2 content adjustment 702
8 Burner, components and heater removal and installation
8.1 General 801
8.2 Burner removal and installation 802
8.3 Removal and installation of the temperature sensor with integrated overheating protection 803
8.4 Hood removal and installation 803
8.5 Combustion air fan removal and installation 804
8.6 Electronic ignition unit and ignition electrode removal and installation 806
8.7 Control unit removal and installation 808
8.8 Fuel pump removal and installation 808
8.9 Solenoid valve removal and installation 810
8.10 Atomiser nozzle removal and installation 810
8.11 Combustion chamber removal and installation 811
8.12 Heat exchanger removal and installation 811
8.13 Heater removal and installation 811
8.14 Start-up after burner or heater installation 812
8.14.1 Bleeding of the fuel system 812
8.14.2 Bleeding of the water circulation 812

Thermo S 160/230/300/350/400 1 Introduction
3
9 Modifications and retrofits
10 Packing / storage
and shipping
10.1 General 1001
Appendix A 1
Periodic heater maintenance A-2

1 Introduction Thermo S 160/230/300/350/400
4

Thermo S 160/230/300/350/400 1 Introduction
101
1Introduction
1.1 Content and purpose
This workshop manual is used to support personnel
briefed and/or trained by Spheros during
maintenance and repair of water heaters Thermo
S160,S230,S300,S350andS400.
1.2 Workshop manual validity
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 valid version is binding.
This version can be found on the Spheros homepage
under Service / Technical Documents.
1.3 Meaning of highlighted content
In this manual sections highlighted with CAUTION,
ATTENTION and NOTE have the following meaning:
CAUTION
This caption is used, if improper adherence or non-
adherence to instructions or procedures may cause injuries
or fatal accidents.
ATTENTION
This caption is used, if improper adherence or non-
adherence to instructions or procedures may cause
component damage.
NOTE
This caption is used, if a distinctive feature is pointed out.
1.4 Additional applicable documentation
We recommend the use of additional documentation.
References are provided in the workshop manual at
appropriate locations.
The following documents can be consulted during
operation and maintenance of the heaters listed on the
title page:
• Operating instruction
• Installation instruction
• Technical communications
• Technical information
• Spare parts list
1.5 Installation and safety regulations
1.5.1 Legal installation regulations
For the heaters exist type approvals according to the ECE
Regulations
R10 (EMC): No. 03 5266 and
R122 (Heater) No. 00 0208 for Thermo S 160
No. 00 0226 for Thermo S 230
No. 00 0227 for Thermo S 300
No. 00 0228 for Thermo S 350
No. 00 0225 for Thermo S 400
Installation is governed above all by the provisions in
Annex 7 of the ECE Regulation R122.
NOTE
The provisions of these Regulations are binding within the
territory governed by ECE Regulations and should
similarly be observed in countries without specific
regulations.
(Extract from ECE Regulation R122, Annex 7)
4. The heater must have a manufacturer’s label showing
the manufacturer’s name, the model number and type
together with its rated output in kilowatts. The fuel type
must also be stated and, where relevant, the operating
voltage and gas pressure.
7.1. A clearly visible tell-tale in the operator’s field of view
shall inform when the combustion heater is switched on or
off.
(Extract from ECE Regulation R122, Part I)
5.3 Vehicle Installation Requirements for
Combustion Heaters
5.3.1 Scope
5.3.1.1 Subject to paragraph 5.3.1.2., combustion
heaters shall be installed according to the requirements of
paragraph 5.3.
5.3.1.2 Vehicles of category O having liquid fuel heaters
are deemed to comply with the requirements of paragraph
5.3.
5.3.2 Positioning of combustion heater
5.3.2.1 Body sections and any other components in the
vicinity of the heater must be protected from excessive
heat and the possibility of fuel or oil contamination.
5.3.2.2 The combustion heater shall not constitute a risk
of fire, even in the case of overheating. This requirement
shall be deemed to be met if the installation ensures an
adequate distance to all parts and suitable ventilation, by
the use of fire resistant materials or by the use of heat
shields.
5.3.2.3 In the case of M2and M3vehicles, the combustion
heater must not be positioned in the passenger

1 Introduction Thermo S 160/230/300/350/400
102
compartment. However, an installation in an effectively
sealed envelope which also complies with the conditions
in paragraph 5.3.2.2. may be used.
5.3.2.4 The label referred to in Annex 7, paragraph 1.4.,
or a duplicate, must be positioned so that it can be easily
read when the heater is installed in the vehicle.
5.3.2.5 Every reasonable precaution should be taken in
positioning the heater to minimize the risk of injury and
damage to personal property.
5.3.3 Fuel supply
5.3.3.1 The fuel filler must not be situated in the
passenger compartment and must be provided with an
effective cap to prevent fuel spillage.
5.3.3.2 In the case of liquid fuel heaters, where a supply
separate from that of the vehicle is provided, the type of
fuel and its filler point must be clearly labelled.
5.3.3.3 A notice, indicating that the heater must be shut
down before refuelling, must be affixed to the fuelling
point. In addition a suitable instruction must be included in
the manufacturer’s operating manual.
5.3.4 Exhaust system
5.3.4.1 The exhaust outlet must be located so as to
prevent emissions from entering the vehicle through
ventilators, heated air inlets or opening windows.
5.3.5 Combustion air inlet
5.3.5.1 The air for the combustion chamber of the heater
must not be drawn from the passenger compartment of
the vehicle.
5.3.5.2 The air inlet must be so positioned or guarded that
blocking by rubbish or luggage is unlikely.
5.3.6 Heating air inlet
not applicable
5.3.7 Heating air outlet
not applicable
5.3.8 Automatic control of the heating system
5.3.8.1 The heating system must be switched off
automatically and the supply of fuel must be stopped
within five seconds when the vehicle’s engine stops
running. If a manual device is already activated, the
heating system can stay in operation.
ATTENTION
Failure to follow the installation instructions and the notes
contained therein will lead to all liability being refused by
Spheros. The same applies if repairs are carried out
incorrectly or with the use of parts other than genuine
spare parts. This will result in the invalidation of the type
approval for the heater and therefore of its ECE Type
Approval.
CAUTION
At petrol stations and other fuel filling facilities the heater
must be switched off due to the explosion hazard. To
advice to this requirement the self-adhesive label with the
text ’’Switch off heater before refueling!“, delivered with
each heater, is to be affixed next to the filler neck.
1.5.2 Installation regulations for railway
vehicles
For heater models Thermo S 230 / 300 / 350 / 400 Rail a
design certification acc. to § 33 EBO (= Federal Railway
Authority) has been issued with the following approval
number: EBA 32AZ3/0006/10.
Particular attention must be given to incidental provision
1.6 of the design certification:
Should the manufacturer, operator or service technician
gain knowledge of any accidents and damage (caused by
fire, explosion, escape of Diesel fuel or heating oil EL) that
may have occurred despite proper use of the heater, he is
required to immediately notify the certifying body thereof.
1.5.3 General safety regulations
General accident prevention regulations must be
observed.
"General safety regulations" beyond the scope of these
regulations are listed below.
The safety regulations must be observed during
operation, maintenance and repair of heaters of the
Thermo S series.
For heaters in vehicles, which are not subjected to the
European Directive, inspection and approval by the
respective inspection authority is required, if applicable
regulations are in place.
The year of first start-up must be permanently marked
on the type plate by removal of not applicable dates.
The heaters are registered and licensed for the use in
vehicles according to the respective EU Directive 70/156/
ECC (e.g. 2001/56/EC). When using the heater for other
applications not subjected to this EU Directive (e.g. ships),
respective applicable regulations must be fulfilled.
ATTENTION
The heaters are not approved for vehicles subjected to
Directive 94/55/EC (ADR).
The heater may only be installed in the driver's cab or
passenger compartment, if an installation box is used,
which can be tightly sealed vs. the vehicle interior. The
installation box must be sufficiently vented from the
outside.

Thermo S 160/230/300/350/400 1 Introduction
103
If the temperature within the installation box exceeds the
permissible ambient temperature of the heater, the
venting opening must be increased after consultation with
Spheros.
ATTENTION
Prior to opening the heater it must be disconnected
from the vehicle electrical system.
NOTE
The heater should always be disconnected from the
vehicle electrical system prior to disconnecting the
temperature sensor plug.
If the order is reversed, the heater will automatically be
interlocked.
Prior to removing the burner from the heat exchanger,
the temperature sensor plug must be removed.
ATTENTION
A temperature of 110°C may not be exceeded in the
heater areas (storage temperature).
Exceeding the temperature may cause heater
malfunctions and permanent damage to the
electronics.
Electrical cables must be routed avoiding isolation
damage (e.g. by pinching, heat development,
bending, fraying, etc.).
CAUTION
For risk of poisoning and suffocation the heater may
not be used in closed rooms such as garages or
workshops without exhaust fume extraction. This
also applies when pre-set times/timers are used. This
also applies for burner operation during adjustment
of the CO2content in the exhaust fumes.
For explosion risk the heater must be switched off at
gas stations and gas systems.
For explosion risk the heater must be switched off,
when combustible fumes or dust can be generated
(e.g. in the proximity of fuel, coal, wood dust, grain
storage/silos or similar).
ATTENTION
The heaters may only be installed in horizontal
position.
CAUTION
If operated without coolant (overheating!), the heaters
outer enclosure may reach the ignition temperature of
diesel fuel during operation!
Dripping or evaporating fuel should not accumulate
or ignite on hot parts or electrical equipment.
The heater should be installed as low as possible to
ensure automatic venting of heater and circulating pump.
This in particular applies for the circulating pump, which
does not automatically draw.
After coolant replacement sufficient purging of the cooling
system must be ensured. Insufficient venting during
heating operation can cause malfunctions due to
overheating.
Proper venting can be recognised by almost noise-free
operation of the circulating pump.
The opening pressure in the vehicle cooling system,
usually indicated on the cooler lid, may not exceed 2.0 bar
working overpressure (also applies to separate heating
circulations).
Hose connections must be secured with hose clamps
against slipping.
ATTENTION
The tightening torques of the used hose clamps must be
observed.

1 Introduction Thermo S 160/230/300/350/400
104
Coolant level verification and cooling system purging
must be performed according to the vehicle
manufacturer's specifications. The coolant in the heating
circulation system should contain at least 20 % of an anti-
freezing agent recommended by the vehicle
manufacturer.
The anti-freezing agent content should not exceed 60 %.
Fuel hoses may not be bent or twisted during installation.
In order to avoid sagging, they should secured using
clamps in 25 cm distances.
Fuel lines must be protected against temperature
exposure.
Permissible fuel line dimensions must be obtained from
the installation instruction.
If a shut-off fitting is installed in the return line, an
information plate must be installed at a well visible
location.
Fig. 101 Heater installation example in a bus
1 Wall heater with fan
2 Heat exchanger at the entrance
3 Heater
4 Circulation pump
5 Roof heat exchanger
6 Vehicle engine
7 Shut-off valve
8 Driver seat heater
9 Control element
Water heating circulation system - wall heater and roof channel heater
Supply
Return
Fig. 102 Information plate

Thermo S 160/230/300/350/400 1 Introduction
105
1.5.4 Combustion air supply
The combustion air intake opening may not point into
driving direction. It should be arranged to effectively avoid
contaminations as well as snow plastering and splash
water intake. Furthermore the combustion air intake
opening should be protected against object penetration by
installing a grid or other suitable measures.
Combustion air intake and exhaust fume outlet must be
arranged to ensure that no air pressure difference (e.g.
suction) will occur in any vehicle operating condition.
Permissible dimensions of the optional, application-
depending combustion air intake line must be obtained
from the installation instruction.
1.5.5 Exhaust line
The exhaust pipe must be secured to the heater using
e.g. a clamp.
Condensation water accumulations must be drained.
If necessary, a condensation water drain hole with a
diameter of Ø 4 must be implemented.
Permissible dimensions of the optional, application-
depending exhaust line must be obtained from the
installation instruction.
The heater exhaust pipe port may not be partially or
completely obstructed by leafs, soil, snow, mud, etc. (this
may occur when the vehicle is driving in reverse). The
exhaust pipe port may not point into driving direction.
Combustion air intake and exhaust fume outlet must be
arranged to ensure that no air pressure difference (e.g.
suction) will occur in any vehicle operating condition.
If the exhaust line is installed in close proximity to
temperature-sensitive parts, then it must be
insulated.
If exhaust fumes exit downwards under the vehicle,
exhaust gas deflection is absolutely necessary.
1.5.6 Adapter wiring harness
ATTENTION
Do not put strain on the adapter wiring harness or adapter
plugs installed for testing purposes.
1.6 Suggestions for Improvement
and change
Please direct any complaints, improvement or
modification suggestions regarding this manual to:
[email protected]

1 Introduction Thermo S 160/230/300/350/400
106

Thermo S 160/230/300/350/400 2 Technical data
201
2 Technical 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
2.1 Electrical components
Control unit, circulating pump, solenoid valve, electronic
ignition and the digital timer are designed for 24V nominal
voltage. Motor nozzle block preheater and temperature
sensor voltages are controlled by the control unit.
NOTE
Recirculating pumps must be assigned to the heaters
according to the flow resistance in the coolant circulation
system. Voltages directly applied to the burner motor for
testing purposes may not exceed 12 V.
2.2 Fuel
Only fuels listed on the type plate as well as fuels
approved by Spheros may be used. The fuel use
limitations in the heater listed below must be observed.
– Diesel fuel according to DIN EN 590 and DIN 51628: The
limitations of use of the standard apply, hence winter
diesel down to - 20°C, Arctic diesel down to - 40°C
– Light fuel oil according to DIN 51603 (above 0°C)
– Bio diesel fuel according to DIN EN 14214: 0 .. - 5 °C
without preheating system, -10 .. - 15 °C with nozzle
block preheater and heated fuel filter (use limitations
depending on fuel quality).
– Diesel -water emulsions: 0 .. - 5 °C without preheating
system, - 10 .. - 15 °C with nozzle block preheater and
heated fuel filter (use limitations depending on fuel
quality/water content).
– 100% Paraffin: - 10°C with nozzle block preheater and
heated fuel filter, the use of lubrication-improving
additives is recommended.
– Mixture of 70 Vol-% diesel fuel (winter diesel)
according to DIN EN 590 or DIN 51628 and 30 Vol-%
Bio diesel according to DIN EN 14214: - 5 .. - 10 °C
without preheating system, - 15°C with nozzle block
preheater and heated fuel filter (use limitations
depending on fuel quality).
– Mixture of 75 Vol-% diesel fuel (winter diesel) according
to DIN EN 590 or DIN 51628 and 25 Vol-% vegetable oil
(rapeseed oil): 0 .. - 5 °C without preheating system,
- 5 .. - 10 °C with nozzle block preheater and heated fuel
filter (use limitations depending on fuel quality).
– Mixture of 75 Vol-% diesel fuel according to DIN EN
590 or DIN 51628 and 25 Vol-% ethanol:
0 .. - 5 °C without preheating system, -5 .. - 10 °C with
with nozzle block preheater and heated fuel filter
Heater Thermo S 160 Thermo S 230 Thermo S 300 Thermo S 350 Thermo S 400
ECE type permit number E1 122R 00 0208 0226 0227 0228 0225
Design High-pressure atomizer
Heat flow rate (at 20°C ambient temperature) kW
(kcal/h)
16
(13 800)
23
(20 000)
30
(26 000)
35
(30 000)
40
(34 000)
Fuel Diesel / light fuel oil
Fuel consumption kg/h 1.6 2.5 3.0 3.6 4.1
Nominal voltage V = 24
Operating voltage range V = 20...30
Electrical power consumption at 24 V * W 50 65 90 120 180
Max. permissible combustion air intake temperature °C + 85
Permissible ambient temperature during operation °C -40...+ 100
Permissible storage temperature °C -40...+ 110
Permissible operating overpressure bar max. 2.0
Heat exchanger filling volume l 1.8
Minimum water flow ** l/h 1400 1900 2400 2700 3200
Minimum circulation volume l 10.0
CO2in exhaust at nominal voltage Vol % 9.5 +1.5
Heater dimensions (tolerance ±3 mm) mm Length 600 / Width 247 / Height 220
Weight kg 18.4 18.8
* without circulating pump
Max. continuous current of the circulating pump 10 A, maximum peak current for 0.5 s duration = 90 A - We recommend the use of Spheros circulation pumps for
highest efficiency and reliability. In order to reduce starting currents the circulating pump can be synchronized by the control unit for a short time period during activation.
Confirm compatibility in case pumps provided by different manufacturers are 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 Technical data Thermo S 160/230/300/350/400
202
ATTENTION
The listed temperature ranges, hence minimum
permissible temperatures strongly depend on the
respective fuel quality. In case of bad-quality fuel the
use limitations may deviate, e.g. in case of too high
water content.
At temperatures below 0°C commercially available winter
diesel should be used. This especially applies for fuel
extraction from a separate fuel tank.
The use of lubrication and flow improving additives is
permitted. No negative impact is known at time of the
preparation of this workshop manual.
ATTENTION
When fuels are used, their respective limitations of
use must be observed and appropriate measures
(nozzle block preheater, electrically heated filter)
must be applied as needed.
In case fuel is extracted from the vehicle tank, the
vehicle manufacturer's mixing regulations shall apply.

Thermo S 160/230/300/350/400 3 Assemblies and components
301
3 Assemblies and components
descriptions
The Spheros Thermo S 160, S 230, S 300, S 350 and
S 400 water heater systems 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. The heat
it transferred to a coolant circulation system via the
heater's heat exchanger. Intermittent operation adjusts
the heater to changing heat demand (cyclic operation).
The control unit controls heater activation and
deactivation based on the temperature sensor signals.
The heaters of the Thermo S series mainly consist of the
following main components:
– Burner
– Combustion chamber
– Heat exchanger
A circulating pump is externally installed in the system, or
for compact devices directly on the heater.
1
2
3
5
6
7
8
9
10
11
4
1 Burner
2 Coolant, intake
3 Sensor plug
4 Temperature sensor with
integrated over-
heating protection
5 Coolant, outlet
Version for additional
sensor
12
6 Heat exchanger
7 Exhaust outlet
8 Fuel, return
9 Combustion air, intake
10 Fuel, flow
11 Splashguard
(screen alternative)
12 Screen
13 Hot air elbow
(incl. adapter)
(screen alternative)
13

3 Assemblies and components Thermo S 160/230/300/350/400
302
3.1 Burner
The burner consists of components
• Burner motor
• Combustion air fan
• Fuel pump with solenoid valve and atomiser nozzle
• Electronic ignition unit with ignition electrode
• Nozzle block preheater, optional
• Control unit with flame detector
• Disc with inspection glass
• Adapter wiring harness as interface to the
temperature sensor system
3.1.1 Combustion air fan
The combustion air fan transports the air required for
combustion from the combustion air intake to the
combustion chamber.
The combustion air fan consists of burner motor, fan and
motor cross member. Air is drawn in through the air intake
opening in the hood. The air intake opening is equipped
with a splashguard, a protective screen and a hot air
elbow.
Two different motors are assigned to the different heating
capacity classes of the Thermo S series. The respective
heating capacity classes are indicated on the motor. In
addition the motors are differentiated by colour.
• 16 kW - 30 KW: Motor housing
colour: silver
• 35 kW - 40 KW: Motor housing
colour: black
3.1.2 Fuel pump
The fuel pump is responsible for fuel supply.
The pump is driven by the burner motor via a coupling.
Fuel is compressed in the fuel pump to approx. 10 bar and
atomised via the atomiser nozzle.
The solenoid valve integrated into the fuel pump opens
and closes the fuel supply to the atomiser nozzle.
Three different fuel pumps are assigned to the different
heating capacity classes of the Thermo S series.
These are identified by the heating capacity class
specification as well as colour dots:
• 16 KW: 1 colour dot
• 23-35 KW: 2 colour dots
• 40 KW: 3 colour dots
Burner motor
Fan
Shaft
circlip
Motor cross member Coupling with
magnets
Nozzle block
preheater (optional)
Solenoid valve
Fuel pump
Screen
O-ring
Colour dots for
identification
of the heating
capacity class

Thermo S 160/230/300/350/400 3 Assemblies and components
303
The fuel pump can be used in dual-line operation (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
– single-line operation
the fuel supply line must be filled prior to first heater start-
up (see 8.14.1).
3.1.3 Nozzle block preheater
In case of very low temperatures fuel may exhibit severely
modified viscosity. Due to insufficient fuel atomisation
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.
The nozzle block preheater consists of a heating element
with an integrated temperature sensor.
At a temperature of < 5°C the heating element heats the
nozzle holder and thus, fuel and atomizer nozzle. Fuel
viscosity is reduced and atomisation improved.
The control unit defines the preheating time depending on
vehicle electrical system voltage and starting temperature.
The use of the nozzle block preheater is optional. It is
possible to retrofit this capability without modifications to
the control unit.
3.1.4 Control unit
The control unit 1586 ensures the operating sequence
and burner operation monitoring.
The flame detector is integrated into the control unit.
Different control units are assigned to the different heating
capacity classes.
The control units are assigned via the ID number and the
performance class indicated on the type plate of the
control unit.
3.1.4.1 Flame detector
The flame detector monitors the flame conditions during
heater operation.
The fame detector is a photo transistor, which changes its
resistance as a function of flame luminous intensity and
thus, the voltage applied.
Nozzle block preheater
Heating element
Control unit 1586
Type plate with
ID number and
heating capacity
class identification
Flame detector

3 Assemblies and components Thermo S 160/230/300/350/400
304
3.1.5 Electronic ignition unit with ignition
electrodes
The electronic ignition unit 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 electrode.
3.1.6 Temperature sensors with water
temperature sensor and integrated
overheating protection
The water temperature sensor captures the coolant
temperature at the heat exchanger outlet as electrical
resistance.
This signal is transmitted to the control unit, where it is
processed.
The overheating protection integrated into the temperature
sensor is responsible for temperature limitation.
Similar to the water temperature sensor, the coolant
temperature is captured at the heat exchanger outlet as
electrical resistance and transmitted to the control unit.
Overheating protection prevents inadmissibly high heater
operating temperatures.
At a temperature greater than 125°C heater deactivation
and interlocking is initiated.
It is not necessary to manually reset the overheating
protection.
3.1.6.1 Adapter wiring harness
It is possible to disconnect the temperature sensor plug
from the adapter wiring harness. Thus, the hood does not
need to be removed for burner head removal.
Flame detector Window
Electronic ignition unit Disc
Electronic ignition unit
Ignition electrode
Temperature
sensor

Thermo S 160/230/300/350/400 3 Assemblies and components
305
3.2 Heat exchanger
The heat exchanger 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.
Coolant inlet
Coolant outlet
Exhaust outlet

3 Assemblies and components Thermo S 160/230/300/350/400
306
3.3 Combustion chamber
The combustion chamber is used for generation and
combustion of the fuel air mixture. The generated exhaust
gas heats the coolant flowing through the heat exchanger.
Three different combustion chambers are used for heaters
of the Thermo S series. Deviating from the standard
combustion chamber variant for Thermo S 230, S 300 and
S 350, the Thermo S 160 is equipped with a combustion
chamber with a sheet metal swirler and the Thermo S 400
is equipped with a burner pipe with increased wall
thickness (1.5 mm).
The combustion chambers of Thermos S 160 and Thermo
S 400 are each fitted with a stamping to distinguish the
individual combustion chambers.
NOTE
If possible, the combustion chamber should be inserted
into the heat exchanger in such a way, that the burner
pipe welding seam is between 60° and 300° in the lower
area.
At the same time it must be ensured that none of the
4 cut-outs of the combustion-chamber head points
vertically downwards (see figure on the right).
It is permissible to change the position during maintenance
or after combustion chamber replacement vs. the previous
installation position.
Combustion chamber
Identification
of the heating
capacity class
Welding seam
Swirl plate
16 KW
23 - 35 KW
40 KW
Cut-out positions
on the combustion
chamber head
in installed condition