Operating instructions

C: Engine pre-heating and/or Boost Heating Only (fig. 403)
This type of installation is used where engine pre-heating and or
system boost heating is the primary requirement. The heater can be
installed across the heating circuit before any of the vehicle heating
cores or installed independently of the vehicles heating circuit by
plumbing directly from and returning back into the engine. Depending
on how the Webasto heater is controlled (timer, switch, vehicle
system), heat can be supplied for engine pre-heating and maintaining
higher operating temperatures. Interior heating efficiency will be
enhanced by the higher operating temperatures provided by boost
heating.
Fig. 403: Engine Preheat/Boost Heating Circuit
Instructions for options A, B or C (Typical installations)
On typical systems, the coolant supply will originate at the engine.
From there, it will travel through the supply hose to the Webasto
coolant pump (or vehicle manufacturer supplied boost pump), through
the pump and into the fuel fired heater where the coolant is heated
during operation. The heated coolant then leaves the heater at the
outlet and continues on through the vehicles heating system and
returns to the engine.
1. Identify the type of system you are working with to determine the
appropriate type of installation as shown in figures 401, 402 or 403.
- find and identify heating circuit supply hose. This is the starting
point for determining the type of plumbing configuration you
will choose.
2. Connect heater into the system according to the examples shown in
figures 401, 402 or 403.
NOTE
Silicone hose requires
special hose clamps.
NOTE
Heater hose must meet
SAE 20 R3 specifications.
NOTE
Hose clamps must be
tightened to to 45 in/lb.
(5 Nm) torque.
WARNING
When working on the
coolant system, allow the
engine to cool down and
open the radiator cap
carefully.
Thermo 230/300 4 Installation
405