8 Service work Thermo 90 S / Thermo 90 ST
804
8.6 Visual inspections and installation
instructions
8.6.1 Connection to the vehicle cooling system
In thermostat circuits, only use thermostats which start to
open at < 65 °C.
The heater should be installed in as low a position as
possible to allow the heater and circulating pump to be
bled automatically.
This is particularly important as the circulating pump is not
self-priming.
The heater is connected to the vehicle cooling system as
shown in Fig. 801. The system must contain at least
6 litres of coolant.
The coolant hoses supplied by Webasto must always be
used. If you do not use these hoses, the hoses that you do
use must comply with DIN 73411. The hoses must be
installed without kinks
and (to ensure perfect bleeding)
rising if possible.
Hose connections must be supported by hose clips to
prevent them slipping.
NOTE
The hose clips must be tightened with a torque of 4 Nm.
The cooling system must be bled carefully before using
the heater for the first time or after replacing the coolant.
The heater and lines should be installed in such a way as
to ensure static bleeding.
Perfect ventilation can be identified by the circulating
pump operating almost silently. Poor bleeding may cause
the resetting temperature limiter to trip whilst the heater is
operating.
8.6.2 Connection to the vehicle fuel system
The fuel is taken from the vehicle fuel tank or from a
separate fuel tank.
The values for the maximum pressure at the fuel
extraction point are shown in the table below.
Only for ADR:
The statutory regulation of ADR (Accord
européen relatif au transport international des
marchandises dangereuses par route) governing fuel
tanks, part 9 para. 9.2.4.7, must be adhered to.
NOTE
A sign must be affixed to the fuel filler neck warning that
the heater must be switched off before refuelling.
Fig. 802 Fuel supply
Permissible fuel inflow
height H (m)
At max. pressure (bar) in
fuel line
0.00 0.20
1.00 0.11
2.00 0.03
Maximum fuel intake
height S (m)
At max. negative pressure
(bar) in fuel tank
0.00 -0.10
0.50 -0.06
1.00 -0.02
l
1
+l
2
≤ 10.0 m
l
1
≤ 1.2 m
l
2
≤ 8.8 m
