Operating instructions

1. Introduction
1.1 General Description
Fig. 101: Webasto Thermo 90 S Coolant Heater
The Webasto Thermo 90 S is designed to be used on any diesel or gasoline equipped vehicle
(diesel and gasoline versions available) including: trucks, small buses, vans, construction, off-road
and military equipment, generators and independent heating systems.
Webasto Thermo 90 S Coolant Heater Applications:
1. Engine block preheating of liquid cooled engines to ensure reliable starting in cold weather and
to reduce cold start wear and emissions (white smoke).
2. Sleeper and engine block heating with the engine off. The heater will increase the driver’s
comfort in cold weather, cut down on unnecessary idling and reduce engine and transmission
wear, as well as, air and noise pollution.
3. Boost heating with the engine running. The heater will boost the heating system in cold weather
when an engine is running at light loads, even at high speeds or idling. The heat rejection of
modern diesel engines to the coolant, especially in buses, is often no longer adequate to heat the
vehicle’s interior.
4. Cargo heating - The heater can be used in independent heating systems to protect valuable
cargo (produce, beverages, paint) from freezing.
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Thermo 90 S 1 Introduction