Hot Air System; Heating Air Intake - Webasto Dual Top ST 6 Installation Instructions Manual

9 | Hot air system

9 Hot air system
NOTE
The heater must not be integrated into the vehicle heat-
ing system.
The recirculating air system ensures frost protection of the wa-
ter hoses with underfloor installation. It also contributes to a
high total efficiency and avoids fumes from the outside being
drawn inside. You can only use the recirculating air system
with air intake from the interior.
Use the control panel to adjust the interior temperature 41 to
95 ºF (5 to 35 ºC). Heat is generated with a diesel-operated
burner. The
Dual Top ST 8 also generates heat with an electric heater,
combining both devices (not available in North America). Power
of the Dual Top ST 8 electric heater, depending on the type and
setting:
n Low power = 1,000 W.
n High power = 2,000 W.
The heating capacity is automatically adjusted by the diesel
powered heater and modulated between 1,500 W and 6,000 W
depending on the output requirement. This is calculated from
difference between selected temperature and current interior
temperature.
To make sure that the heater functions satisfactorily, the flow
resistance of the connected hot air system must be minimized.
At maximum speed of the hot air fan, the maximum pressure
drop between the inlet and outlet side of the hot air line is 3.0
hPa (hectopascal).
Make sure that the air flow (air velocity) does not differ more
than factor two, comparing the two hot air distribution chan-
nels.
If the resistance of the hot air ducts is too high, the temperature
sensors inside the heater will detect a high air temperature. This
results in a higher speed of the hot air fan, causing more noise
and power consumption.
You must secure the hot air hoses (inlet and outlet) with clamps
or screws at their connection points.
NOTE
Check the installation for:
u
No air due to a short circuit between the vehicle's
heating system and the heater air inlet.
u
No air due to a short circuit between the heater's air
inlet and its air outlet, see also Fig. 21.
u No air due to leakage from openings created to
route the hoses in or out of the interior.
Dual Top ST
2
1
Fig. 21
1 Air inlet for the heater
2 Air outlet for the heater
12 / 32
Dual Top ST
2
1
9.1

Heating air intake

9.1.1 General
NOTE
The heating air must be drawn from the interior.
Extracting heating air from an enclosure, such as the bottom of
the bed or the seat box, will reduce noise from the hot air fan.
Mounting the air intake in a central area provides even air circu-
lation throughout the interior.
Do not position the heating air inlet too low. This minimizes the
risk of dirt and small particles being sucked in. If necessary,
mount an air grille on the heating air intake.
Webasto recommend to position the inlet sufficiently above
floor level.
Make sure that no fluids can be spilled into the air inlet.
Fig. 22
If an air intake hose is used, its internal diameter must be
3.6 in (90 mm).
9.1.2 Installation
The length of air intake hose outside the interior shall be as
short as possible, ideally less than 3.3 ft (1 m). This is to
avoid heat losses and to protect the water pipes from
freezing. For the same reason, thermal insulation of the air
intake hose is re-quired.
Fig. 23 Heating air intake
1.
Determine the position of the hole in the floor through
which you want to pass the air intake hose.
2. Drill a hole in the floor with a diameter of 4 in (100 mm).
3.
Seal the joint between the floor and the air intake hose
with temperature resistant sealing compound (up to 194 ºF
90 °C).
4.
Outside the vehicle, insulate the air intake hoses to protect
the water lines against frost and to minimize energy loss.
9026389C II Dual Top ST 6