Webasto Thermo 90 ST User manual

Wasserheizgerät
Water heater
xxx
Einbauanweisung
Installation Instructions
Thermo 90 ST WDT
Thermo 90 ST WDT (Diesel)

Thermo 90 ST WDT
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.
To install and repair Webasto heating and cooling systems you need to have completed a Webasto training course and have the
appropriate technical documentation, special tools and special equipment.
Only genuine Webasto parts may be used. See also Webasto air and water heaters accessories catalogue.
NEVER try to install or repair Webasto heating or cooling systems if you have not completed a Webasto training course, you do not
have the necessary technical skills and you do not have the technical documentation, tools and equipment available to ensure that
you can complete the installation and repair work properly.
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.

Table of Contents
II
Table of Contents
1 Regulations governing installation.................................................. 34
1.1. Statutory regulations governing installation ................... 34
1.2. Additional documentation to be used............................ 34
2 Use / version .................................................................................. 35
2.1. Use of the water heaters ............................................... 35
2.1.1. Parking heater ............................................ 35
2.2. Version.......................................................................... 35
3 Installation ..................................................................................... 36
3.1. Installation location/installation position of the heater
and control unit ............................................................ 36
3.2. Installing heater............................................................. 36
3.3. Installing control unit..................................................... 36
3.4. Using rub guard ............................................................ 37
4 Type label ...................................................................................... 37
5 Installation example ....................................................................... 38
6 Integration in coolant system ......................................................... 39
6.1. Connection ................................................................... 39
6.2. Checking....................................................................... 39
7 Fuel integration.............................................................................. 40
7.1. General Information ...................................................... 40
7.2. Integration in vehicle fuel tank....................................... 42
7.3. Integration in engine return line .................................... 43
7.4. Fuel line ........................................................................ 44
7.4.1. Line installation........................................... 44
7.4.2. Line design ................................................. 45
7.4.3. Connecting two lines with a hose ............... 45
7.4.4. Metering pump........................................... 45
7.4.5. Installation location..................................... 45
7.4.6. Installation position and attachment ........... 45
7.4.7. Fuel filter .................................................... 46
7.5. Label ............................................................................. 47
7.6. Cold-resistant fuels........................................................ 47
8 Combustion air supply ................................................................... 48
9 Exhaust System .............................................................................. 49
9.1. Exhaust pipe.................................................................. 49
9.2. Exhaust silencer ............................................................. 49
9.3. Recommendations for installation.................................. 49
10 Electrical connections ..................................................................... 51
10.1. Connection of control unit / heater................................ 51
10.2. Installation and connection of the heater controls.......... 51
10.5. Connector types ............................................................ 51
10.6. Earth connection ........................................................... 52
10.7. Using adapter wiring harness......................................... 52
10.8. Setting control temperatures ......................................... 52
11 Circuit diagrams............................................................................. 53
12 Initial start-up................................................................................. 58
13 Malfunctions.................................................................................. 59
13.1. Fault lock-out ................................................................ 59
13.2. Diagnosis in case of fault lock-out ................................. 59
13.2.1. Equipment with standard timer ................... 59
13.2.2. Equipment with switch................................ 60
14 Technical data................................................................................ 61
14.1. Technical data Thermo 90 ST WDT ................................ 61
14.2. Electrical Components ................................................... 61
14.3. Fuel for Thermo 90 ST WDT........................................... 61
14.4. Military standards met for Thermo 90 ST WDT............... 61

Thermo 90 ST WDT
33
Note
Mechanical system
Electrical system
Coolant circuit
Fuel
Exhaust gas
Combustion air
Caution
Technical information
Explanatory Notes on Document
To provide you with a quick overview of the individual working steps, you will find an identification mark on the outside top corner of the page in question.
Sections in italics contain an excerpt from the Directive ECE-R 122.

Technical Information
34
1 Regulations governing installation
1.1. Statutory regulations governing installation
Type approvals according to ECE-R 10 (EMC) and ECE-R 122 (Heater) exist
for the Thermo 90 ST WDT heater.
See chapter 14, "Technical data" for the approval number.
1.2. Additional documentation to be used
These installation instructions do not contain all necessary information and
instructions with regard to the installation of Thermo 90 ST WDT heaters.
In addition, the operating instructions must also be used.
The provisions of these Directives are binding within the
territory governed by EU Directive 70/156/EEC and/or EC/
2007/46 (binding for new vehicle types as of 29/04/2009) and
should also be observed in countries in which there are no
special regulations!
Failure to follow the installation instructions and the notes
contained therein will lead to all liability being refused by
Webasto. 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 homologation/ECE type approval.

Technical Information
35
2 Use / version
2.1. Use of the water heaters
2.1.1. Parking heater
The Thermo 90 ST WDT water heater was designed for use in military
vehicles. When installing in other special vehicles, the applicable
regulations must be taken into account. Other uses are possible in
consultation with Webasto.
The Webasto Thermo 90 ST WDT water heater is used in conjunction with
the original vehicle heating system in the parking heating mode
– for heating the cab,
– for defrosting the vehicle windows,
– to pre-heat water-cooled engines (if technically possible).
The water heater operates independently of the vehicle engine and is
integrated in the vehicle's cooling system, fuel system and electrical system.
2.2. Version
Thermo 90 ST WDT - Diesel
Water heater for "diesel" fuel.
The heater is designed for 24 V.
See chapter 14, "Technical data" for the technical design.

Technical Information
36
3 Installation
The water heater must be installed outside the passenger cabin.
If the vehicle manufacturer has issued instructions, they must be
followed.
3.1. Installation location/installation position of the heater and
control unit
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.
(Requirement from ECE-R 122, Point 5.3.2.1.).
The 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.
(Requirement from ECE-R 122, Point 5.3.2.2.).
Installation should be carried out as low as possible to ensure automatic
bleeding of the heater and circulation pump. This is particularly important
as the circulation pump is not self-priming.
Fig. 1 Permissible installation positions for Thermo 90 ST WDT
3.2. Installing heater
Every reasonable precaution should be taken in positioning the heater to
minimize the risk of injury and damage to personal property.
(Requirement from ECE-R 122, Point 5.3.2.5.).
The heater must be secured on the bracket with at least 3x M8 bolts with
18 Nm.
3.3. Installing control unit
The control unit must be secured with at least 4x M6 nuts with 8 Nm. The
installation position can be selected as desired, however the permissible
protection type must be observed! A suitable connection between the eart-
hing pins and the vehicle earth must be provided to ensure EMC protection.
The heater may not be installed:
– in the direct area of radiation of exhaust systems
– below the wading line of the vehicle.
– above the coolant expansion tank.

Technical Information
37
3.4. Using rub guard
A suitable rub guard must be provided when installing the heater wiring
harness (see Fig. 1, marked with “X”) to prevent damage to the braided
shield.
4 Type label
The label referred to in Annex 7, paragraph 4, or a duplicate, must be
positioned so that it can be easily read when the heater is installed in the
vehicle.
(Requirement from ECE-R 122, Point 5.3.2.4.).
The type label must be located in an area protected against damage.
Inapplicable years must be erased from the type label and the current year
must be retained.
Fig. 2 Example of type label

Technical Information
38
5 Installation example
Fig. 3 Example of Thermo 90 ST WDT installation in a vehicle.
Without check valve (on left) and with check valve and thermostat (on right)
Coolant circuit
Exhaust pipe
Fuel line
Wiring harness
Combustion-air intake pipe
1) Heat exchanger of vehicle heater
2) Switch for fan of vehicle heater
3) Relay for vehicle fan
4) Standard timer
5) Fuse block in vehicle
6) Check valve with leakage hole
7) T-piece
8) Vehicle engine
9) Water heater
10) Circulation pump
11) Water pump
12) Radiator
13) Control valve
14) Exhaust silencer
15) Metering pump
16) Combustion-air intake pipe
17) Thermostat
18) Control unit

Coolant circuit
39
6 Integration in coolant system
6.1. Connection
In thermostat circuits, only use thermostats which start to open at < 65 °C.
The heater is connected to the vehicle cooling system as shown in Fig. 3.
The coolant quantity present must at least be equivalent to the volume
specified in chapter 14, "Technical data".
It is preferable to integrate the heater in the coolant system at the vehicle
heat exchanger inlet.
The coolant hoses supplied by Webasto must always be used. If other hoses
are used, they must at least comply with the standard DIN 73411, material
class B. The hoses must be routed without kinking and preferably uphill
from the heater to ensure perfect bleeding.
Hose connections must be supported by hose clips to prevent them slip-
ping.
Care must be taken to bleed the cooling system before the heater is taken
into service for the first time or after refilling with fresh coolant. Heater and
lines should be installed in such a way as to ensure static bleeding.
Perfect ventilation can be identified by the circulation pump operating
almost silently.
Malfunctions due to overheating may occur during operation if the heater
and lines have not been bled correctly.
6.2. Checking
After the heater and all coolant-carrying components have been installed,
the entire coolant system must be checked for leaks with the system
pressure specified by the vehicle manufacturer.
Any coolant running off should be collected using an
appropriate container.
The hose clips must be tightened with a torque of 4 Nm.

Fuel
40
7 Fuel integration
7.1. General Information
The fuel filler must not be situated in the passenger compartment and must
be provided with an effective cap to prevent fuel spillage.
(Requirement from ECE-R 122, Point 5.3.3.1.).
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.
(Requirement from ECE-R 122, Point 5.3.3.2.).
The fuel line is divided into the intake and the delivery line. As a result, the
intake line is a connection between the fuel tank and the metering pump,
while the delivery line produces the connection between the metering
pump and the heater.
The values for the maximum pressure at the fuel extraction point and the
permissible line lengths are shown in the following tables and in Fig. 4.

Fuel
41
Fig. 4 Fuel supply
Suction side:
D1: Inside diameter of fuel line = 2 mm.
H1: Dimension for fuel tank over metering pump [m]
S1: Dimension for fuel tank under metering pump [m]
l1: Length of fuel line
l1 1.2 m
Pressure side:
D2: Inside diameter of fuel line = 2 mm.
l2: Length of fuel line
l2 8.8 m
Permissible fuel inflow height H1
[m]
At max. perm. pressure in fuel line
[bar]
0.00 0.20
1.00 0.11
2.00 0.03
Permissible fuel suction height S1
[m]
At max. perm. vacuum in fuel line
[bar]
0.00 -0.10
0.50 -0.06
1.00 -0.02

Fuel
42
7.2. Integration in vehicle fuel tank
The fuel must be removed from the fuel tank or a separate tank (see Fig. 5,
Fig. 6 and Fig. 7).
Also see chapter 5, "Installation example", with Fig. 3.
The specified securing measures of the vehicle manufacturer must be
complied with.
Deburr the cut on the tank connector after sawing it off and
remove any metal chips.
Fig. 5 Fuel removal from a plastic fuel tank; removal via fuel-
tank sending unit
Fuel standpipe
Fuel-tank sending unit
Sealing ring

Fuel
43
Fig. 6 Fuel removal from a plastic fuel tank; removal via fuel-
tank drain screw Fig. 7 Webasto fuel standpipe
On Fig. 7: The valve and/or fuel tank must be made from metal!
7.3. Integration in engine return line
Fuel may only be removed from the return line with the special Webasto
fuel standpipe. In this case, it must be ensured that the return line reaches
almost up to the bottom of the fuel tank and is not closed by a check valve.
The fuel extractor must be fitted in such a way that any air or gas bubbles
are automatically discharged towards the tank (see Fig. 8).
The fuel extractor must not be located near the engine, as gas bubbles may
form in the lines on account of heat radiated from the engine. This may
cause problems during combustion.
Plastic tank
Sealing ring
Only use fuel standpipe with
metal fuel tank
Hole diameter: 25 mm

Fuel
44
Fig. 8 Webasto fuel standpipe
7.4. Fuel line
Since the lines normally cannot be routed with a constant rising gradient,
the internal diameter must not be allowed to exceed a certain size. Air or
gas bubbles will accumulate in lines with an internal diameter of more than
4 mm and these will cause malfunctions if the lines sag or
are routed downwards. The diameters specified in Fig. 4 will ensure that
bubbles do not form.
7.4.1. Line installation
When installing the fuel line, it must be kept as short as possible.
See Section 7.1, "General Information".
The line must be installed protected against damage (e.g. stone impact) in
all areas.
The fuel line must always be routed in cool areas to prevent the formation
of bubbles due to warming. High fuel temperatures can cause heater
malfunctions. As a result, the line may not be routed either past strong heat
sources (e.g. exhaust gas) or near stored heat zones.
In addition, the steepest possible routing of the fuel line must be ensured
from the fuel tank to the heater.
Fuel lines must be fastened in accordance with the latest technology so
that, for example, line sag is avoided.
Rub protection must be installed at sharp-edged transitions.
To engine
To metering pump
From fuel tank
Do not route fuel lines through the vehicle interior.

Fuel
45
7.4.2. Line design
Only steel and plastic lines made of light and temperature-resistant PA11 or
PA12 (e.g. Mecanyl RWTL) approved by Webasto and in accordance with
DIN 73378 may be used as fuel lines.
7.4.3. Connecting two lines with a hose
The correct connection of fuel lines with a hose is shown in Fig. 9.
Ensure freedom from leaks!
Fig. 9 Pipe/hose connection
7.4.4. Metering pump
The metering pump is a combined delivery, metering and shut-off system
and is subject to specific installation criteria (see Fig. 4, Fig. 10 and Fig. 11).
The Thermo 90 ST WDT heater may only be operated with the DP2 or 30.2
metering pumps.
7.4.5. Installation location
Before installing the metering pump, make sure that the maximum pressu-
re at the removal point is below 0.2 bar.
The metering pump may not be installed in the radiation area of hot vehicle
parts. A heat shield must be used if necessary. The pump should preferably
be installed near the tank.
For the permissible ambient temperature, see chapter 14, "Technical data".
7.4.6. Installation position and attachment
The metering pump must be secured with a vibration-damping mounting.
The installation position is restricted as shown in Fig. 10 or Fig. 11
(maximum inclination of metering pump, axial installation position of
metering pump) to ensure good self-bleeding.
The arrow indicates the direction of flow of the fuel.
Cut lines without burr and do not crush them.
Do not cut them with side-cutting pliers.
Hose clamp Air bubble

Fuel
46
Fig. 10 DP2 metering pump
Installation position and mounting
Fig. 11 30.2 metering pump
Horizontal installation position
7.4.7. Fuel filter
Only a Webasto filter, order no. 487 171, is allowed to be used if the fuel
is expected to be contaminated. Install vertically if possible, however at
least horizontally. See Fig. 12.
Note the installation position and direction of flow.
The arrow indicates the direction of flow of the fuel.
Fig. 12 Fuel filter

Fuel
47
7.5. Label
A notice, indicating that the heater must be shut down before refuelling,
must be affixed to the fuelling point.
(Requirement from ECE-R 122, Point 5.3.3.3.).
Use included adhesive label (for an example, see Fig. 13).
The sticker "Switch off heater when refuelling“ must be applied near the
filler neck.
Fig. 13 Example of adhesive label “Switch off heater when refu-
elling“
7.6. Cold-resistant fuels
If you change to low-temperature fuel, the heater must be operated in the
boost mode (full load) for approx. 15 minutes so that fuel line and fuel
pump are also filled with the new fuel.
Also see the section 14.3, "Fuel for Thermo 90 ST WDT".

Combustion air
48
8 Combustion air supply
The air inlet must be so positioned or guarded that blocking by rubbish or
luggage is unlikely.
(Requirement from ECE-R 122, Point 5.3.5.2.).
Under no circumstances may the combustion air be taken from areas occu-
pied by people.
The intake opening for combustion air must be located so that it cannot
become clogged with dirt. It must not point in the direction of travel.
The withdrawel point for the combustion air must be located in a cool place
where it is protected from splashing water and above the fording line of the
vehicle.
An intake line is required for combustion air.
A combustion air pipe with a minimum length of 0.5 m and a minimum in-
side diameter of 30 mm must be used.
The maximum permissible length of the combustion air pipe is 5.0 m.
The combustion air pipe may have several bends; the total bending angles
may not exceed 360°.
The smallest bending radius is 45 mm.
The combustion air intake must not be routed above the exhaust outlet.
If the heater is installed in a general installation space near the vehicle’s fuel
tank, the combustion air must be taken in from the outside and the exhaust
fumes discharged into the atmosphere. The openings must be splash-
proof.
A ventilation opening measuring at least 6 cm2is required if the heater is
installed in an enclosed box. The size of the ventilation opening must be
increased accordingly if the temperature in the box exceeds the permitted
ambient temperature of the heater (see chapter 14, "Technical data").
If the combustion-air intake pipe from the outlet opening to
the heater cannot be routed with a continual upward incline,
then a 4 mm dia. water drain hole must be drilled at the lowest
point.

Exhaust gas
49
9 Exhaust System
9.1. Exhaust pipe
The exhaust pipe (inside diameter 38 mm) can be routed with several bends
(360° altogether, minimum bending radius 85 mm).
The total line length must be between 0.5 and 5 mm.
Lines approved by Webasto must be used as exhaust pipes.
9.2. Exhaust silencer
It is not permissible to operate the Thermo 90 ST WDT heater without
exhaust silencer.
The exhaust silencer must be installed near the heater and must not be
installed near the intake opening for the combustion air.
9.3. Recommendations for installation
The exhaust silencer and the exhaust pipe may not be fastened to tem-
perature-sensitive vehicle parts (e.g. brake line, electr. lines, vehicle control
units, headlights, underbody protection, plastic parts, etc.) and must be a
sufficient distance of at least 40 mm from them.
Only approved Webasto spacer brackets may be used with this application.
The exhaust pipes are sufficiently fixed in place to ensure the minimum
distances even during driving.
It is recommended that the exhaust application be installed splash-water
protected.
The exhaust pipe is secured to the heater using a clamping collar, for
example.
Exhaust gases escaping from condensed-water drain holes may not blow
onto temperature-sensitive vehicle parts.
The exhaust outlet must be located so as to prevent emissions from
entering the vehicle through ventilators, heated air inlets or opening
windows.
(Requirement from ECE-R 122, Point 5.3.4.1.).
The exhaust outlet must be unobstructed. It must not be directed at vehicle
parts. The exhaust outlet may not be located within the range of throw of
the wheels.
Watch the maximum steering angle of the front wheels. It must be ensured
that the exhaust outlet is not clogged and cannot be damaged under any
operating conditions.
The opening of the exhaust pipe must not point in the direction of travel.
The exhaust pipe should be secured no further than 150 mm from the end
of the exhaust pipe to ensure that the angle of 90° ± 10° is achieved
See Fig. 14.
After passing through the underbody cover, the exhaust pipe must be ex-
tended by another 10 mm.
When installing the exhaust silencer, it must be ensured that
the condensed water can run off through the condensed-wa-
ter drain hole of the silencer.
Collections of condensed water in the exhaust pipe must be
drained off directly. If necessary, a condensed-water drain hole
may be drilled at the lowest point.