Webasto Air Top 2000 D, Air Top 2000 B Service And Repair Manual

List of Contents

Air Top 2000

– Improper installation or repair of Webasto heating and cooling systems can cause

fire or the leakage of deadly carbon monoxide leading to serious injury or death.

– Installation and repair of Webasto heating and cooling systems requires special

Webasto training, technical information, special tools and special equipment.

– NEVER attempt to install or repair a Webasto heating or cooling system unless you

have successfully completed the factory training course and have the technical skills,
technical information, tools and equipment required to properly complete the
necessary procedures.

– ALWAYS carefully follow Webasto installation and repair instructions and heed all

WARNINGS.

– Webasto rejects any liability for problems and damage caused by the system being

installed by untrained personnel.

Air Heater

Air Top 2000 D (Diesel)
Air Top 2000 B (Gasoline)

Service and Repair Manual

NOTE

Technical changes in this issue of the

manual compared with its previous issue

are identified with a vertical change bar on

the lefthand side of columns.

I

List of Conten ts

1. Introduction

1.1 Scope and Purpose.................................................................................................................................101

1.1.1 Use of Air Heaters.................................................. .......... .......... .......... ........ .......... .......... .......... .101

1.2 Meaning of Warnings, Cautions, and Notes............................................................................................101

1.3 Additional Documentation to be used......................................................................................................101

1.4 Safety Information and Regulations........................................................................................................101

1.4.1 General Safety Notes..................................................................................................................101

1.5 Legal Provisions for Installation........................................................ ................ ................ ................ .......102

1.6 Corrections and Improvements............ ................ ................ ................ ................ ................ ................ ...103

2. General Description

2.1 Combustion and Heating Air Fan ............................................................................................................201

2.2 Heat Exchanger.................................................................... ................ ................ ................ ................ ...202

2.3 Burner Insert with Com bustion Tube........................ .......... ........ .......... .......... .......... .......... ........ .......... ...202

2.4 Control Unit / Control Circuit Board.................... ................ ................ ................ ................ ................ .....202

2.5 Flame Sensor..........................................................................................................................................203

2.6 Glow Plug................................................................... ................................................ .............................203

2.7 Temperature Limite r....................... .......... .......... ........ .......... .......... .......... .......... ........ .......... .......... .........203

2.8 Dosing Pump...........................................................................................................................................203

3. Functional Description

3.1 Functional Description Air Top 2000 without Diagnosis (Fig. 301)..........................................................301

3.1.1 Control Element..........................................................................................................................301

3.1.2 Switch-On....................................................................................................................................301

3.1.3 Stabilization................................................................................................................ .. .. .. .. .. .. .. .. .301

3.1.4 Heating Operation.......................................................................................................................301

3.1.5 Control Operation........................................................................................................................302

3.1.6 Control Idle..................................................................................................................................302

3.1.7 Switch-Off....................................................................................................................................302

3.1.8 Functions of the Air Heater in TRS Vehicles.............................................. .......... .......... ........ .....302

3.1.9 Switch-Off upon Failure...............................................................................................................302

3.2 Functional Description Air Top 2000 Diagnosis.......................................................................................304

3.2.1 Control Element..........................................................................................................................304

3.2.2 Switch-On....................................................................................................................................304

3.2.3 Stabilization................................................................................................................ .. .. .. .. .. .. .. .. .304

3.2.4 Heating Operation.......................................................................................................................305

3.2.5 Control Operation........................................................................................................................305

3.2.6 Control Idle..................................................................................................................................305

3.2.7 Switch-Off....................................................................................................................................305

3.2.8 Functions of the Air Heater in TRS Vehicles.............................................. .......... .......... ........ .....305

3.2.9 Switch-Off upon Failure...............................................................................................................306

4. Technical Data .... ........ ............ ........ ........ ............ ........ ............ ........ ........ ............ ........ ............ ........ ........ .......401

Air Top 2000

List of Contents

II

5. Troubleshooting

5.1 General....................................................................................................................................................501

5.2 General Failure Symptoms......................................................................................................................501

5.3 Failure Symptoms during Operation........................................................................ ................................502

5.4 Error Code Output (Air Top 2000 Diagnosis) .............................................................. ................ ............503

6. Functional Tests

6.1 General....................................................................................................................................................601

6.2 Adjustments.............................................................................................................................................601

6.2.1 Adjustment of the CO

2

Contents......................... .......................................................... ..............601

6.3 Components Testing .. .. .... .. .. .. .. .. .. .... .. .. .. .. .. .. .... .. .. .. .. .. .. .... .. .. .. .. .. .. .... .. .. .. .. .. .. .... .. .. .. .. .. .. .... .. .. .. .. .. .. ...........602

6.3.1 Glow Plug Resistance Test.........................................................................................................602

6.3.2 Flame Sensor Resistance Test...................................................................................................602

7. Circuit Diagrams

7.1 General....................................................................................................................................................701

8. Servicing

8.1 General....................................................................................................................................................801

8.2 Work on the Air Heater........................ ........ .......... .......... .......... .......... ........ .......... .......... .......... .......... ....801

8.3 Work on the Vehicle ................................................................................................................................801

8.4 Air Heater Test Run.................................................................................................................................801

8.5 Servicing..................................................................................................................................................801

8.6 Visual Inspections and Installation Regulations ......................................................................................801

8.6.1 Heating Air System .......... ........ .......... .......... .......... .......... ........ .......... .......... .......... .......... ........ ....801

8.6.2 Fuel Supply..................................................................................................................... ............802

8.6.3 Dosing Pump...............................................................................................................................804

8.6.4 Fuel Filter................ ........ .......... .......... .......... .......... ........ .......... .......... .......... .......... ........ .......... ..804

8.6.5 Combustion Air Supply................................................................................................................805

8.6.6 Exhaust Line ...............................................................................................................................805

8.6.7 Combustion Air Intake and Exhaust Lines..................................................................................805

8.6.8 Electrical Connections.................................................................................................................806

8.7 Removal and Installation.........................................................................................................................8 08

8.7.1 Air Heater, Removal and Installation..................................................... ................ ................ ......808

8.7.2 Replacement of Control Unit.......................................................................................................808

8.7.3 Replacement of Temperature Limiter..........................................................................................808

8.8 Installation of new Control Units............................ ................................................ ..................................811

8.8.1 Replacement of Control Unit Air Top 2000 (12 Volt)

with External Temperat ure Sensor.............................................................. ................ ................811

8.8.2 Replacement of Control Unit Air Top 2000 (24 Volt) not TRS.....................................................811

8.8.3 Replacement of Control Unit Air Top 2000 (24 Volt) TRS...........................................................812

8.9 First Operation.........................................................................................................................................812

List of Contents

Air Top 2000

9. Repair

9.1 General....................................................................................................................................................901

9.1.1 Work on Components after Disassembly....................................................................................901

9.1.2 Incorporation of Modifications................ .. ................................................ .. .................................901

9.2 Disassembly and Assembly.....................................................................................................................902

9.2.1 Removal of Housing Components/Covers..................................................................................902

9.2.2 Replacement of Control Unit................................................................................ .......................904

9.2.3 Replacement of Temperature Limiter................................................................. ................ .........904

9.2.4 Replacement of Combustion Air Fan ..........................................................................................905

9.2.5 Replacement of Flame Sensor....................................................................................................906

9.2.6 Replacement of Glow Plug..........................................................................................................906

9.2.7 Replacement of Burner Insert, Combustion Tube, and Heat Exchanger....................................909

10. Packaging/Storage and Shipping

10.1 General..................................................................................................................................................1001

III

Air Top 2000

List of Contents

Lis t of Figu res

301 Functional Diagram (Air Top 2000 without Diagnosis)....................................................................................303

501 General Failure Symptoms............................................................................... ........ ........ ........ ........ ........ ......501

502 Failure Symptoms during Operation....................................................... .......... .......... .......... .......... .......... ......502

601 Adjustment of CO

2

Contents ..........................................................................................................................601

701 Terminal Pin Assignment, Air Top 2000 Diagnosis.........................................................................................701

702 Terminal Pin Assignment, Air Top 2000 without Diagnosis............................................................................702

703 Circuit Diagram Automatic Control Air Top 2000 Diagnosis, 12V/24V with Control Element.........................703

704 Circuit Diagram Automatic Control Air Top 2000 Diagnosis, 12V/24V with Combination Tim er.....................704

705 Circuit Diagram Automatic Control Air Top 2000 Diagnosis,

12V/24V with Control Elem ent and Standard Time r....................................... ................ ................ ................705

706 Circuit Diagram Automatic Control Air Top 2000 Diagnosis,

24V TRS Operation with Control Element.................. ................ ................ ................ ................ ................ ....706

707 Circuit Diagram Automatic Control Air Top 2000 Diagnosis,

24V TRS Operation with Combination Tim er...................................................... ................ ................ ............707

708 Circuit Diagram Automatic Control Air Top 2000 Diagnosis,

24V TRS Operation with Combination Timer and 2 Auxiliary Drives..............................................................708

709 Circuit Diagram Automatic Control Air Top 2000 without Diagnosis, 12V with Control Element....................709

710 Circuit Diagram Automatic Control Air Top 2000 without Diagnosis,

12V with Control Element and Timer............................................ ................ ................ ................ ................ ..710

711 Circuit Diagram Automatic Control Air Top 2000 without Diagnosis, 24V with Control Element....................711

712 Circuit Diagram Automatic Control Air Top 2000 without Diagnosis,

24V with Control Element and Timer............................................ ................ ................ ................ ................ ..712

713 Circuit Diagram Automatic Control Air Top 2000 without Diagnosis,

24V with Control Element , TRS............................................ ................ ................ ................ ................ ..........713

714 Circuit Diagram Automatic Control Air Top 2000 Diagnosis,

24V TRS Operation with Control Element in Vehicles w ithout Auxiliary Drive................................................714

715 Connection Diagram, Air Top 2000 Diagnosis with Combination Timer (not TRS!)...................................... ..715

801 Fuel Supply.....................................................................................................................................................802

802 Webasto Fuel Tank Tap .................................................................................................................................803

803 Fuel Tapping from Plastic Tank (tapping via fuel drain plug).................................................. ................ ........803

804 Fuel Tapping from Plastic Tank (tapping via fitting plate)......................................................................... ......803

805 Pipe/Hose Connection....................................................................................................................................804

806 Dosing Pumpe, Installation Position and Attachment....................................................................... ..............804

807 Fuel Filter.............................................................................................................. .. ........................................804

808 Exhaust Muffler, Direction of Flow..................................................................................................................805

809 Exhaust Pipe Outlet, Installation Position................................................................................. ................ ......805

810 Removal of Fuse Holder Attachment Plate.....................................................................................................806

811 Fuse Holder, Installation Position ............................................. ................ ................ ................ ................ ......806

812 Control Element...................................................................................................................................... .... ....806

813 Pulling the Plug...............................................................................................................................................806

814 Example of an Installation...............................................................................................................................807

815 Replacement of Control Unit and Temperature Limiter (Air Top 2000 without Diagnosis).............................809

816 Replacement of Control Unit and Temperature Limiter (Air Top 2000 Diagnosis)..........................................810

901 Removal of Housing Components/Covers......................................................................................................903

902 Replacement of Combustion Air Fan (Removal) ............................................................................................904

903 Replacement of Combustion Air Fan (Disassembly)................................ ................................................ ......905

904 Disassembly of Heat Exchanger......................................................................................................... ............907

Lis t of Figu res

Air Top 2000

IV

1. Introduction

1.1 Scope and Purpose

This repair shop m anual is intended to support famil­iarized personnel in the repair of air heaters Air Top
2000 of the fuel and Diesel type as well as of Air Top
2000 Diagnosis with serial no. 30.000 and up.

1.1.1 Use of Air Heaters

The air heaters Air Top 2000 and Air Top 2000 Diag­nosis are used to

- heat the cabin

- defrost the windscreens.
They are not cleared for heating a transportation com-

partment for dangerous goods.
The heaters operate independent from the vehicle en­gine and are connected to the fuel tank and to the electri­cal system of the vehicle. Their use is possible in
vehicles with water- or air-cooled engines.

1.2 Meaning of Warnings, Cautions
and Notes

WARNINGS, CAUTIONS, and NOTES in this manual
have the following meaning:

WARNING

This heading is used to highlight that non-compliance
with instructions or procedures m ay cause injuries or
lethal accidents to personnel.

CAUTION

This heading is used to highlight that non-compliance
with instruct ions or procedures may cause d am age to
equipment.

NOTE

This heading is used to highlight and draw specific atten­tion to information.

1.3 Additional Documentation to be used

This workshop manual contains all informat ion and pro­cedures necessary for the repair of heaters Air Top 2000
and Air Top 2000 Diagnosis.
The use of additional documentation is normally not
necessary.
Operating instructions/ins tallat ion instruct ions and the
vehicle specific installation proposal may be used as
complementary informat ion as necessary .

1.4 Safety Information and Regulations

The general safety regulations for the prevention of acci­dents and the relevant operating safety instructions have
to be observed at all times."General Safety Regulations"
beyond the scope of these regulations are detailed in the
following.The specific safety regulations applicable to
this manual are highlighted in the individual chapters by
Warnings, Cautions, and Notes.

1.4.1 General Safety Notes

Within the scope of the StVZO (Road Licensing Regula­tions of the Federal Republic of Germany) “Design
General Approvals”, laid down by the Federal Office for
Motor Traffic, exist for the Water Heater Air Top 2000
and Air Top 2000 Diagnosis with the following official
marks of conformity:

-S 270 (Diesel)

-S 277 (Fuel)

The installation of the heaters is to be performed in ac­cordance with the installation instructions and must b e
checked in case of
a) the vehicle ty pe inspect ion in accordance with

§ 20 StVZO

b) the individual inspect ion in accordance with

§ 21 StVZO or

c) the examination in accordance wit h § 19 StVZO

performed by an officially authorised expert or exam­iner for road traffic, a vehicle inspector or a public
servant as per section 7.4 a of Annex VIII to the

StVZO.
In the event of c) the installation must be certified on the
acceptance certificate included in the copy of the
“General Operating License” giving details about

- manufacturer

- type of vehicle , and

- vehicle identif ication num ber.
This validates the “Design General Approval”.

The acceptance certificate must be kept with the
vehicle.
The year of first operation must be permanently
marked on the identification label.

The heaters are cleared for heating the passenger and
driver cabins but not for heating compartments intended
for the transportation of dangerous goods.
The use of the heater in special vehicles (e.g. vehicles
for the transportation of dangerous goods TRS) or ve­hicles not subject to the StZVO (e.g. ships) are ruled by
partially regional regulations.
For the installation of the

AT 2000 D in vehicles used for
the transportation of dangerous goods, in addition to the
StVZO, the requirements in TRS 002 and TRS 003
(Technical Guidelines for the Transportation of Dan­gerous Goods on Roads) must be met.

101

Air Top 2000

1 Introduction

The heater must not be installed in the passenger or
driver compartments of busses. Should the heater never­theless be installed in such a compartment, the installa­tion box must be sealed tight against the vehicle interior.
There must be sufficient ventilation of the installation box
from the exterior in order not to exceed a maximum tem­perature of 40 °C in the installation box.

At filling station s and fuel depots the heat er must be
switched off as there is a potential dan ger of explo ­sion.

Where flammable fumes or dust may build up (e.g.
in the vicini ty of fuel, coal , wood, cereal depots, or
similar installat ions) the heat er must be switched off
to prevent explosions.

Due to the danger of poisoning and suffocation the
heater must not be operated in enclosed areas such as
garages or workshops without exhaust venting, not even
if the start-up is activated by the timer or telest art device.

When removing the heater the gasket below must be re­placed.

The heat exchanger of the air heater remains service­able for a maximum of 10 years and must then be r e­placed with an original spare part by the manu­facturer or by one of its authorized workshops.
The heater must then be provided with a label
marked with the sales date and with the words “Orig­inal Spare”.
Should exhaust pipes be rou ted through rooms
accommodating person s, these pipes shal l also be
renewed after 10 years.

Installations not legally authorized will void the air
heater’s “Official Marks of Conformity” and thus the
vehicle’s permit of operation. The same applies for
repairs performed by unskilled personnel and repairs
with no original spare parts.

1.5 Legal Provisions for Installation

For testing the heater in accordance with 19, 20, or 21
of the StVZO the following regulations are to be ob­served in particular (§ 22 a StVZO):

Testing is performed upon presentation of the operating
and installation instructions of the manufacturer.

The year of the initial operation must be durably marked
on the heater identification plate by the installing person.

Heating Air System

Heating air intake openings must be arranged so that
under normal operating conditions exhaust fumes of the
vehicle engine or air heater are not likely to be expected.

Extracting combustion air from the vehicle interior is not
permissible.

Combustion A ir Line

The combustion air required must be taken from the
exterior.
Within rooms accommodating persons, the com bust i on
air lines must not have more than four disconnects and a
splash-water protected ext erior w all feedthrough. The
disconnects must be sealed in a way not to exceed a
leak rate of 200 l/h at an overpressure of 0.5 mbar.
The line including feedthrough, disconnects, material
and specific type must be described in the installation
instructions.
The line must require tools for installation and removal,
must be protected against damage, and must be shock­proof.

Exhaust Line

Heaters must be designed to discharge the exhaust to
the exterior.

Exhaust pipes must be routed so that exhaust fumes are
unlikely to penetrate into the vehicle’s interior.
The function of any parts of the vehicle essential for its
operation must not be impaired. Condensate or water
penetrated must not be able to accumulate in the
exhaust line.
Drain holes are permissible; these must drain the fluid to
the exterior via lines sealed against the vehicle interior.

The exhaust line outlet is to be positioned to the top, to
the side, or in case of exhaust venting below the vehicle
floor, to the nearest possible location of the vehicle’s or
cockpit’s side or rear end. In compartments accommo­dating persons, exhaust lines must not have more tha n
one disconnect and must have a splash-water protected
feedthrough in the exterior wall/floor . For water , that has
penetrated into the exhaust line, the connection of a
drain line with a metal-sealing joint is permissible. The
drain pipe must be routed sealed through the exterior
wall or the vehicle floor.The heat exchanger, the exhaus t
line connected, as well as the possible drain pipe must
be sealed so that with an overpressure of double the
overpressure of the exhaust having the maximum per­missible exhaust line length - at least however at an over­pressure of 0.5 bar - a total leak rate of 30 l/h is not
exceeded.

The line including feedthrough, disconnects, material
and specific type must be described in the installation
instructions.
The line must require tools for installation and removal,
must be protected against damage, and must be shock­proof.

102

1 Introduction

Air Top 2000

Metal lines must be used. These m ay not heat to mo re
than 110 °C should there be the possibility of contact
within the room interior. Protective devices against con­tact may be fitt ed.
Should exhaust pipes be routed through rooms accom­modating persons, these pipes shall be renewed after 10
years using genuine spare parts.

Combustion Air Inlet and Exhaust Outlet

During installations these ports for combustion air entry
and exhaust fume exit must be of such type, that a ball
with a diameter of 16 mm cannot be inserted.Elec tric al
lines, switch gear and control gear of the heater must be
located in the vehicle so that their proper function cannot
be impaired under normal operating conditions.

For the routing of fuel lines and the installation of addi­tional fuel tanks §§ 45 and 46 of the StVZO are to be
adhered to.
The most important regulations are: Fuel lines are to be
designed in such a way that they remain unaffected by
torsional stresses in the vehicle, engine movement and
the like. They must be protected against mechanical
damage.
Fuel-carrying parts are to be protected against ex­cessive heat and are to be arranged so that any dripping
or evaporating fuel can neither accumulate nor be ig­nited by hot components or electrical equipment.
In busses, fuel lines and fuel tanks may be located
neither in the passenger area nor in the driver’s compart­ment. In these type of vehicles the fuel tanks must be lo­cated such that they do not pose a direct hazard to the
exits in the event of a fire. Fuel supply must not be by
means of gravity or pressurization of the fuel tank.

Installatio n Rules for Webasto Fuel Tanks for the
Fuel Supply of Heaters in Vehicles

In busses the installation is not permitted in the pas­senger or driver compartment.
The fuel fill neck must in no vehicle be located within any
of these compartments.
Fuel containers for carburettor fuel must not be located
immediately behind the front panelling of the vehicle.
They must be sparate from the engine so that even in
case of an accident the inflammation of fuel is unlikely to
be expected. This does not apply for towing vehicles
with an open cockpit.
The operational state of the heater, i.e. an indication “on”
or “off”, must be easily and clearly visible.

1.6 Corrections and Improvements

Deficiencies, improvements , or proposals for correction
of this workshop manual are to be mailed to:

Webasto Thermosys tem e Gmb H
Abt. Technische Dokumentation
D-82131 Stockdorf

Telephone: 0 89 / 8 57 94 - 5 42
Telefax: 0 89 / 8 57 64 10

103

Air Top 2000

1 Introduction

2. General Description

The air heater Air Top 2000 and Air Top 2000 Diagnosis
with serial no. 30.000 and up operat ing to the evaporator
principle basically consist of:

- combustion and heating air fan

- heat exchanger

- burner insert with combustion tube

- control unit

Air Heater Air Top 2000

For control and monitoring a

- control unit/control circuit board

- flame sensor

- glow plug

- temperature limiter

- temperature sensor
are located within the unit.
12 Volt heaters (Air Top 2000 without Diagnosis) may be

controlled by means of an external temperatur e sensor.
All heaters of air Top 2000 Diagnosis may be controlled
by means of an external temperature sensor.

Fuel supply is provided externally by a fuel dosing pump.

Air Heater Air Top 2000 without Diagnosis

(covers removed)

A malfunction in air heaters Air Top 2000 Diagnosis out­puts an error code to the display of the combination or
standard timer. When equipped with a control element
the operating indicator flashes. In addition a heater chec­kout may be performed using a personal computer (refer
to operating instructions PC air heater diagnosis).

Air Heater Air Top 2000 Diagnosis

(covers removed)

2.1 Combustion and Heating Air Fan

The combustion and heating air fan delivers the air re­quired for combustion from the combustion air inlet to
the burner insert. By means of the fan the heating air is
also delivered to the air outlet.

Combustion and Heating Air Fan

201

Air Top 2000

2 General Description

2.2 Heat Exchanger

The heat exchanger dissipates the heat provided by
combustion to the air delivered by the combustion and
heating air fan.

Heat Exchanger

2.3 Burner Insert with Combustion Tube

Within the burner insert fuel is distributed in the combus­tion tube across the burner cross-section. In the combu s­tion tube the combustion of the fuel/air mix ture take s
place heating up the heat exchanger.

2.4 Control Unit / Control Circuit Board

Air Top 2000 without Diagnosis

The control unit/c ontr ol ci rcuit boar d is the cent ral co nt rol­ling unit for functional sequen cing and m on itori ng of the
combustion oper ation . A tempera ture sens or located on
the side is used for temperature co ntrol . 12 Volt heate rs
may have the temperature sensor replaced against an ex­ternal temper at ure sensor. The c om bust ion an d heat in g
air fan may be set by m eans of a po te ntiom et er .

Control Unit Air Top 2000 without Diagnosis

Air Top 2000 Diagnosis

The control unit/control circuit board is the central co n­trolling unit for functional sequencing and monitoring of
the combustion operation. A temperature sensor located
on the control unit is used for temperature control. All
heaters may have the temperature sensor replaced
against an external temperature sensor. The combustion
and heating air fan may be set by means of a poten­tiometer.

A malfunction in air heaters Air Top 2000 Diagnosis out­puts an error code to the display of the combination or
standard timer. When equipped with a control element
the operating indicator flashes. In addition a heater chec­kout may be performed using a personal computer (refer
to operating instructions PC air heater diagnosis).

Combustion
Tube

Burner
Insert

Potentiometer

Temperature
Sensor

202

Fuel
1 mm

Diesel
2 mm

2 General Description

Air Top 2000

Control Unit Air Top 2000 Diagnosis

2.5 Flame Sensor

The flame sensor is a low-Ohm PTC resistor changing
its resistance dependent on its heating by the flame.
The signals are routed to the control unit for processing.
The flame sensor monitors the flame operating condition
over the complete duration of heater operation.

Flame Sensor

2.6 Glow Plug

The glow plug ignites the fuel/air mixture at the start of
the air heater operation. The glow plug is acting as an
electrical resistor and is located in the burner insert
opposed to the flame side.

Glow Plug

2.7 Temperature Limiter

The temperature limiter protec ts the air heater against
excessive operating temperatures . Overheat protec tion
is activated at temperature higher than 150 °C to inter­rupt the electrical circuit of the dosing pump and switch
off the heater with run-dow n operation.
After cooling down the electrical circuit is restored.
The air heater may be switched on again (see 3.9).

Temperature Limiter

2.8 Dosing Pump

The dosing pump is a combined supply, dosing and shut­off system for the fuel supply of the heater out of the
vehicle’s fuel tank.

Dosing Pump DP 2 for Fuel and Diesel operated Heaters

Dosing Pump DP 30 for Diesel operated Heaters

Potentiometer

Temperature
Sensor

203

Air Top 2000

2 General Description

3. F unctional Description

3.1 Functional Description Air Top 2000
without Diagnosis (Fig. 301)

3.1.1 Control Element

The control element is used to switch the air heater on
and off, set the desired room temperature (air intake tem ­perature between 10 °C and 45 °C), and to unlock a
failure interrupt condition.

The green LED indication is used to indicate the opera­ting condition (LED per manently on) and an overheat
condition (LED flashes).

NOTE

After application of power upon swit ch-on of the battery
switch and selecting the contr ol element “ON”, the c on­trol unit enters the “error lockout” condition. Prior to a re­activation the control element has to be placed to “OF F”.

3.1.2 Switch-On

The control element is set to the desired room tempera­ture. When switching the air heater on, the operating indi­cator is illuminated and the glow plug is activated
(cycled). The motor of the combustion and heating air
fan starts high-speed operation for 1 second (break­away moment) and is then under slow -dow n control.

NOTE

Should the temperature of the intake air be above the se­lected, rated temperature, only the mot or of the combus­tion and heating air fan will operate (control idle). Start
operation will be initiated with a heating air temperature
below the rated temperature.

After approx. 20 seconds (for fuel operated heaters after
approx. 15 seconds) the fuel dosing pump is activated.
After another 25 seconds the speed of the combustion
and heating air fan is continuously increased to a higher
rate and combustion begins. As soon as a flame is
detected, combustion w ill be stabilized (see 3.1.3).

Should no normal combustion be achieved within 120
seconds (for fuel operated heaters after approx. 115
seconds), the speed of the combustion and heating air
fan is increased for approx. 30 sec and there will be an
automatic repeat start w ith the glow plug activated an d
fuel dosing pump deactivated (no fuel supply).

Should the no-combustion-condition persist , after an­other 80 seconds (for fuel operated heaters after approx.
85 seconds) there will be a switch-off by error lockout
(see 3.1.9) with a run-down of the combustion and heat­ing air fan lasting 120 seconds at 2/3 of its max. speed.

3.1.3 Stabili zation

Diesel Operated Heaters

With the glow plug activated the operating speed of the
combustion and heating air fan is increased. After an­other 20 seconds the speed of the combustion and heat­ing air fan is continuously increased within 17
seconds to full load for full heat.
A flame-out during the speed rise control period causes
a repeat start.

Fuel Operated Heaters

With the glow plug activated the operating speed of the
combustion and heating air fan is continuously increased
within 4 seconds to full load for full heat. A flame-out dur­ing the speed rise control period causes a repeat start.

3.1.4 Heating Opera tion

During operation the combustion exhaust gasses flow
through the heat exchanger charging its walls w ith com ­bustion heat, which in turn is taken up by the heating air
delivered by the heating air fan to be routed to the
vehicle interior.
The temperature of the heating air sucked in is
measured by means of a temperature sensor fitt ed to
the air intake side of the air heater or in case of 12 Volt
heaters also by means of an externally located tempera­ture sensor. A temperature below the one set with the
control element increases the heater performanc e up to
maximum heat.
In order to extend the burner idle period of Diesel oper­ated heaters during permanent operation with a heating
performance in excess of 1.2 kW, the fuel dosing pump
delivery rate is reduced every 30 minutes for 20 seconds.

A heating performance less than 1.2 kW causes the fuel
delivery to the dosing pump to be interrupted every 30
minutes for 4 seconds. For both types of heaters (fuel
and Diesel) heating operation is shortly interrupted every
9 hours like in control idle.

After reaching the temperature set with the contr ol ele­ment, heating performance is controlled to decrease.
The speed of the combustion and heating air fan slows
down and the fuel delivery rate to the pump is reduced.
When exceeding the air intake temperature set with the
control element during minimum heating perform ance,
the dosing pump is deactivated after 5 seconds and com­bustion terminates.

NOTE

The control unit/air heater reacts to new sett ings of the
control element with a time delay.

301

Air Top 2000

3 Functional Description

3.1.5 Control Operation

During control operation fan speed and dosing pump
rate of delivery are s ubject to heating performance.
The glow plug is deactivated.

3.1.6 Control Idle

In case the air intake temperature set with the cont rol ele­ment is exceeded and the minimum heating perfor­mance had been achieved f or longer than 5 seconds,
the fuel supply is cut off to terminate combustion.
The motor of the combustion and heating air fan con­tinues operation for another 155 seconds at 2/3 of maxi­mum speed to cool down the air heater (run-down). In
control idle the combustion and heating air fan runs at
minimum speed. The operation indication remains lit.
After reaching the air intake temperature set with the
control element a n ew start procedure is launched (with­out break-away) .

3.1.7 Switch-Off

Switching the heater off ext inguishes the operation indi­cation of the control element.
If no fuel has been delivered (within 20 seconds for Die­sel operated heaters or within 15 seconds for fuel oper­ated heaters after switch-on) or if the air heater is in
control idle, the air heater is deactivat ed immediately
without run-down.

If fuel supply has commenced it will be immediately
stopped at switch-off. The fan speed decreases within
35
seconds to 2/3 of maximum.
Subsequently or if the flame sensor detects “no flame”
the fan speed is increased to maximum for 60 seconds
and run-down is initiated to last 120 seconds. Run-down
is automatically halted.

NOTE

Re-activation of the heater during run-down is permitted.
Run-down will be completed first wit h a subsequent re­start.

3.1.8 Functions of the Air Heate r in
TRS Vehicles

NOTE

Applicable only for Air Top 2000 D Air Heaters installed
in vehicles for the transportation of dangerous goods
(TRS).

If the heater is deactivated using the control element,
run-down will not change.

A short run-down (max. 40 seconds) is automatically
activated if:

l

the vehicle engine is turned off

l

a conveyor facility is put into operation

The short run-down time depends on the operational
condition at which TRS swit ch-off occurs.
A 40 second run-down with maximum speed is initiate d
(TRS switch-off) when:

l

air heater is still in the start phase; stabiliz ation
not yet achieved

l

air heater is in normal run-down

l

air heater is in control idle.

A 20 second run-down is switched on in normal combus­tion operation with the fuel delivery immediately halted
maintaining the fan speed for 5 seconds. Then the
speed is increased for 30 seconds within another 5 sec­onds.

For all heaters after July 1995 the short run-down
out of all operating conditions is a max. of 20 sec­onds.

After a TRS switch-off the control unit is in the “error
lockout” condition.
Prior to resuming operation the control element has to
be set to “OFF”.

3.1.9 Switch-off upon Failure

The control unit recognises failures of individual air
heater components and malfunctions in the start se­quence and in normal operation.

The air heater is deactivated and enter s the error lockout
mode under the following conditions:

l

flame sensor resistance out of tolerance

l

temperature sensor resistance out of tolerance

l

glow plug/glow plug trigger defective

l

fan speed too low, short circuit or open circuit

l

error in dosing pump electrical circuit or of
overheat protection (in start phase only)

l

low voltage below 10 Volt and in excess of 20
seconds for 12 Volt heaters

l

low voltage below 20 Volt and in excess of 20
seconds for 24 Volt heaters

l

control unit defective

In case of overheating there will be no fuel supply. A run­down like after manual switch-off w ill be performed.
After run-down the control unit is in the error lockout
mode. Overheating is indicated by the operation indica­tion flashing. For error unlock the air heater has to be
switched off momentarily to be switched on again.

302

3 Functional Description

Air Top 2000

303

On

A

0

1

1 2

3 4

5 6 7 8

9

10

B

C

0

1

100%
90%
60%
30%
0

D

1,3 Hz
1,0 Hz
0,8 Hz
0,6 Hz
0

E

F

0

1

0204565 85 102

secondstypical

(20) (60)

(120)

Fig. 301 Functional Diagram (Air Top 2000 without Diagnosis)

1 Start
2 Control Operation
3 Rated Value reached
4 Rated Value exceeded

(e.g. due to reduc ed heat sumption)
5 Run-down
6 Control Idle
7 Start
8 Control Operation (increased heat consumption)
9 Switch-off
10 Run-down

A = Control Element
B = Temperature Sensor
C = Glow Plug
D = Combustion and Heating Air Fan
E = Dosing Pump
F = Flame Sensor

Air Top 2000

3 Functional Description

304

3.2 Functional Description Air Top 2000
Diagnosis

3.2.1 Control Element

The control element is used to switch the air heater on
and off, set the desired room temperature (air intake tem ­perature between 10 °C and 45 °C), and to unlock a
failure interrupt condition.

The green LED indication is used to indicate the opera­ting condition (LED permanently on) and an overheat
condition (LED flashes).

NOTE

TRS Operation:

After application of power upon switch-on of the battery
switch and selecting the control element “ON” , the con­trol unit enters the “error lockout” condition. Prior to a re­activation the control element has to be placed to “OFF”.

3.2.2 Switch-On

The control element is set to the desired room tempera­ture. When switching the air heater on, the operating indi­cator is illuminated and the glow plug is activated
(cycled). The motor of the combustion and heating air
fan starts high-speed operation for 1 second (break­away moment) and is then under slow-down control to
approx. 30% (Diesel) or 50% (fuel) of full speed.

NOTE

Should the temperature of the intake air be above the se­lected, rated temperature, only the mot or of the combus­tion and heating air fan will operate (control idle). Start
operation will be initiated with a heating air temperature
below the rated temperature.

The flame sensor function is checked. If the flame sen­sor at this time already signals “flame”, there will be a
120 second run-down and an error lockout of the control
unit. A malfunction of any other component monitored
causes an error lockout without run-down.

After approx. 20 seconds (for fuel operated heaters after
approx. 15 seconds) the fuel dosing pump is activated.
After another 25 seconds the speed of the combustion
and heating air fan is continuously increased to a higher
rate and combustion begins. As soon as a flame is
detected, combustion will be stabilized (see 3.2.3).

Should no normal combustion be achieved within 120
seconds (for fuel operated heaters after approx. 115
seconds), the speed of the combustion and heating air
fan is increased for approx. 30 sec and there will be an
automatic repeat start w ith the glow plug activated a nd
fuel dosing pump deactivated (no fuel supply).

Should no proper combustion develop within 120 sec­onds (for fuel-operated within 115 seconds) the combus­tion and heating air fan speed is increased to full load for
approx. 30 seconds (15 seconds for fuel-operated
heaters) with the glow plug on and the dosing pump off
(no fuel delivery) with a subsequent automatic restart.

Should the no-combustion-condition persist, after an­other 80 seconds (for fuel operated heaters after approx.
85 seconds) there will be a switch-off by error lockout
(see 3.2.9) with a run-do w n of the combustion and heat­ing air fan lasting 120 seconds at 2/3 of its max. speed.

2. Start (automatic restart)

Fan speed is again reduced to approx. 30% (for fuel
operated heaters to approx. 50%) and fuel is delivered.
During the next 20 seconds fan speed is increased to ap­prox. 60% (for fuel-operated heaters to approx. 75% ) of
full speed. As soon as a flame is detected within the next
55 seconds, combustion will be stabilized. Should there
be no flame condition after a total fuel delivery period of
180 seconds, fuel delivery will be stopped and the glow
plug deactivated. The combustion air fan continues full
load operation for another 120 seconds (run-down) and
the heater enters the error lockout condition.

3.2.3 Stabilization

Diesel Operated Heaters

With the glow plug activat ed the operating speed of the
combustion and heating air fan is increased. After an­other 20 seconds the speed of the combustion and heat­ing air fan is continuously increased within 17 seconds
to full load for full heat.

NOTE

This operating condition is omitted if the set temperature
(control idle) has already been achieved once.
The glow plug is deactivated and heating operation com­mences. A flame-out during speed up control causes a
restart, 5 restarts an error lockout of the heater.

Fuel Operated Heaters

With the glow plug activat ed the operating speed of the
combustion and heating air fan is continuously increased
within 4 seconds to full load for full heat. This operating
condition will be omitted if the start occurs after a control
idle period.
The glow plug is deactivated and heating operation com­mences. A flame-out during speed up control causes a
restart, 5 restarts an error lockout of the heater.

3 Functional Description

Air Top 2000

3.2.4 Heating Operation

During operation the combustion exhaust gasses flow
through the heat exchanger charging its walls with com ­bustion heat, which in turn is taken up by the heating air
delivered by the heating air fan to be routed to the ve­hicle interior.
The temperature of the heating air sucked in is
measured by means of a temperature sensor fitted to
the air intake side of the air heater or by means of an ex­ternally located temperature sensor.
A temperature below the one set with the control ele­ment increases the heater performance up to max imum
heat. In order to extend the burner idle period of Diesel
operated heaters during permanent operation with a
heating performance in excess of 1. 1 kW, the fuel dos­ing pump delivery rate is reduced every 15 minutes for
20 seconds.

A heating performance less than 1.1 kW causes the fuel
delivery to the dosing pump to be interrupted every 30
minutes for 4 seconds. Additionaly heating operation is
briefly suspended every 9 hours like in control idle. For
Diesel-operated heaters this is only applicable, if at this
time heating performance is less than 1.1 kW.

3.2.5 Control Operation

During control operation fan speed and dosing pump
rate of delivery are subject to heating performance.
The glow plug is deactivated.

3.2.6 Control Idle

After reaching the temperature set w ith the cont rol ele­ment, heating performance is controlled to decrease.
The speed of the combustion and heating air fan slows
down and the fuel delivery rate to the dosing pump is re­duced. When exceeding the air intake temperature set
with the control element during minimum heating perfor ­mance, the dosing pump is deactivated after 5 seconds
and combustion terminates.
Fan speed remains constant for 35 seconds and is then
increased to approx. 60% of full speed for cooling the
heater down. the fan then continues to operate at ap­prox. 30% of full speed until temperature is below the
temperature set with the control element. If temperature
falls below the one set with the control element, the
heater will restart (wit hout break aw ay ).

NOTE

New settings on the control element are executed b y the
control unit/heater w ith a time delay.

3.2.7 Switch-Off

Switching the heater off ext inguishes the operation indi­cation of the control element.
If no fuel has been delivered or if the air heater is in con­trol idle, the air heater is deactivated immediately
without run-down.

If fuel supply has commenced it will be immediately
stopped at switch-off. Fan speed remains constant and
then decreases within 30 seconds to approx. 60% of full
speed. After this or with the flame sensor detecting “ no
flame”, fan speed rises to maximum speed for 60 sec­onds and run down for 120 seconds is initiated. Run­down is at approx. 60% of full speed and is deactivated
automatically.

NOTE

Re-activation of the heater during run-down is permitted.
Run-down will be completed first wit h a subsequent re­start.

3.2.8 Functions of the Air Heate r in
TRS Vehicles

NOTE

Applicable only for Air Top 2000 D Air Heaters installed
in vehicles for the transportation of dangerous goods
(TRS).

If the heater is deactivated using the control element,
run-down will not change.
A short run-down (max. 20 seconds) is automatic ally
activated if:

l

the vehicle engine is turned off

l

a conveyor facility is put into operation

The short run-down time depends on the operational
condition at which TRS switch-off occurs.
A 15 second run-down with maximum speed is initiated
(TRS switch-off) when:

l

air heater is still in the start phase; stabilization
not yet achieved

l

air heater is in normal run-down

l

air heater is in control idle.

A 20 second run-down is switched on in normal combus­tion operation and in stabilization with the fuel delivery
immediately halted maintaining the fan speed for 5 sec­onds. Then the speed is increased to maximum for 15
seconds within for a run-down.

After a TRS switch-off the contr ol unit is in the “error
lockout” condition.
Prior to resuming operation the control element has to
be set to “OFF”.

305

Air Top 2000

3 Functional Description

3.2.9 Switch-off upon Failure

The control unit recognises failures of individual air
heater components and malfunctions in the start se­quence and in normal operation.

The air heater is deactivated and enters the error loc­kout mode under the following conditions:

l

flame sensor open or short circuit

l

temperature sensor open or short circuit

l

glow plug open or short circuit

l

fan motor open or short circuit or fan speed wrong

l

dosing pump open or short circuit

l

overheating

l

low voltage below 10 Volt or high voltage above
15 Volt in excess of 20 seconds for 12 Volt heaters

l

low voltage below 20 Volt or high voltage above
30 Volt in excess of 20 seconds for 24 Volt heaters

A switch-off like in “sw itch-off” will be performed.
In case of overheating there will be no fuel supply. After
run-down the control unit is in the error lockout mode.
The operation indication outputs a flash code.
For error unlock the air heater has to be switched off
momentarily (at least 2 seconds) to be switched on

306

3 Functional Description

Air Top 2000

4. Technical Data

As long as no threshold values are given, the following
technical data are understood to include tolerances of

±10% usual for heaters at an ambient temperature of
+20 °C and at nominal voltage and conditions.

Electrical Components:

Control unit, combustion air fan, dosing pump, timer*,
glow plug and control element are for 12 or 24 Volts
operation.

The components temperature limiter and flame detec tor
are independent of voltage.

*not for TRS

Permitted ambient temp.:
Heater:

Dosing pump:
Control element:

- operation

- storage

- operation

- storage

- operation

- storage

Air Heater Operation

AT 2000 B

Mark of conformity

Heater type

Heat flow

Type of fuel

Fuel consumption

Nominal voltage

Operation voltage

Rated power consumption

Volume flow of heating air
against 0.5 bar

CO

2

in exhaust

(perm. functional range)
Dimensions air heater

Weight, heater

Control range

Air heater with

evaporator burner

1.1 – 2.0 kW

Fuel

0.1 .. 0.2 kg/h (0.16..0.27 l/h)

10 … 15 Volt

12 Volt

9 ...22 W

-40 ° … +40 °C

-40 ° … +85 °C

-40 ° … +20 °C

-40 ° … +85 °C

-40 ° … +75 °C

-40 ° … +85 °C

+10 ... +45 °C

70 m

3

/h

9.5 … 10.5

Length 322 ± 2 mm

Width 130 ± 1 mm

Height 122 ± 1 mm

2.6 kg

Control range

Max.

Max.

~ S 277

AT 2000 D

0.9 – 2.0 kW

Diesel/Fuel oil (EL)

0.1 .. 0.21 kg/h (0.12 .. 0.24 l/h)

20 … 30 Volt

12 Volt

9.5 … 12.0

~ S 270

Control range

24 Volt

10 … 15 Volt

Control range

Permitted combustion air
intake temperature

-40 ... +20 °C

Setting range for
indoor temperature

401

Air Top 2000

4 Technical Data