Webasto HL 90 Owner's Manual - page 29
HL 90
8 Servicing
805
8.6.5 Combustion Air Supply
Combustion air must under no circumstances be
extracted from rooms with persons. The combustion air
inlet must not point towards the forward direction of
motion. It must be located so that no clogging by
contamination is to be expected.
If the air heater is located in a closed installation box,
combustion air must be taken in from and the exhaust
routed to the exterior. The splash water proof
feedthroughs must not allow exhaust fumes to enter the
vehicle interior.
In order to silence the air intake noises an air intake
muffler (included in delivery of 24 v units) is recommended
(Fig. 809). The muffler is fitted onto the air intake pipe.
NOTE
For 12 V units it is recommended to install an air intake
muffler (Order No. 876 59A).
Fig. 809 Air Intake Muffler
8.6.6 Exhaust Line
Rigid pipes made of unalloyed or alloyed steel with a
minimum wall thickness of 1.0 mm have to be used as
exhaust line or flexible pipes made of alloyed steel only.
The exhaust pipe is secured to the air heater e.g. with a
clamp.
The exhaust muffler is preferably mounted near the air
heater. The direction of flow is optional.
Fig. 810 Exhaust Muffler, Direction of Flow
Operation of the air heater is also permitted without
muffler.
8.6.7 Combustion Air Intake and Exhaust Lines
Length of combustion air intake line:
with muffler:
max. 3.0 m
without muffler:
max. 5.0 m
Length of exhaust line: max. 5.0 m
Both lines are to be routed away from the heater in a
decline. If this is not possible, a condensate drain hole
Ø 4 mm must be provided at the lowest point.
Inner diameter of lines:
combustion air line:
30 mm
exhaust line:
38 mm
Smallest bending radius:
combustion air line:
45 mm
exhaust line:
85 mm
In order to ensure an angle of 90° ±10°, an attachment
is required not further than 150 mm away measured from
the exhaust pipe end.
Fig. 811 Exhaust Pipe Outlet, Installation Position
WARNING
Other installation position of exhaust pipe outlet than
shown in Fig. 811 may cause fires.
Sum of bends:
combustion air line:
max. 360°
exhaust line:
max. 360°
10
°
10
°
Direction of exhaust flow
nearly vertical 90° ±10°