Operating instructions

Fig. 407: Exhaust Discharge Positioning
4.5 Combustion Air Supply
A combustion air intake tube I.D. 1.18" (30 mm) must be installed on the “Basic” and “Compact”
versions of the Thermo 90 S heater.
Combustion air intake tubing should be kept as short as possible and should not exceed 6.5’ (2m).
Bends in the combustion air tubing should not exceed 360° total. The smallest bending radius
allowed is 1.8" (45mm).
Combustion air should always be taken from a clean area, and should be routed in a gradual
downward slope away from heater allowing moisture to drain.
The intake opening of the combustion air tube must not point in the direction of travel to avoid any
possible clogging caused by snow, mud or foreign materials.
406
4 Installation Thermo 90 S
WARNING
Never draw combustion air from inside the vehicle, or from areas where fumes or gases can
accumulate. Drawing of combustion air from areas where people are present is strictly prohibited!