Onan NHC Series Operator's/Service Manual And Parts Catalog page 9

INSTALLATION
The type of installation can affect the . life of the
engine, the cost of operation and the frequency of
necessary service. Plan the installation carefully to
ensure the best performance.
Because of the great variety of uses, and the many
variations of the engine, these installation instruc-
tions are typical or general in nature. Use the
installation recommendations given as a general
guide.
MOUNTING
There are several acceptable methods of. mounting
the engine. Among factors to be considered are:
location, method of coupling the engine to the load,
type of foundation or support, etc. The engine should
be mounted on a level surface if possible. Maximum
operation angle is 15 degrees sideways, 30 degrees
front to rear tilt. If the engine is to operate at an angle, •
be sure to re-mark the oil level indicator to compen-
sate for the tilt.
AIR
O U T
VENTILATION
The engine must be provided with asupply of fresh air
for cooling and for combustion.
Pressure Cooled Engine: Position the air inlet open-
ing directly in front of the engine and as close to the
engine blower wheel as possible. The area ofthe inlet
should be not less than 80 square inches. If louvers or.
grill work ere used, increase the area to compensate
forthe reduced airflow. Provideextra ventilation ifthe
driven load generates heat during operation.
The heated air outlet must allow the heated air to
escape freely and prevent recirculation with the
cooling air. A duct between the compartment air inlet
and the engine blower housing may be necessary.
Locate the air outlet opposite the intake or at least at a
90 degree angle. The area of the outlet should be at
least 15 percent larger than that of the inlet. Allow
sufficient room on all sides to permit access for
servicing.
FIGURE 1. AIRFLOW THROUGH VACU-
FLO SYSTEM
Vacu-F!o Cooled Engine: The vacu-flo equipped
engine uses an integral flywheel-centrifugal fan to
pull cool air into the engine shroud and over the
cooling fins and surfaces of the engine, Figure 1. The
heated air is directed through an air tight scroll which
encases the flyvyheel fan. The scroll may be position-
ed to discharge heated air in the downward, upward,
left or right direction. This is possible because the
back section of the scroll (Figure 2) has four identical
holes shaped to fit over the<end of the starter motor.
The scroll outlet has a mesh-type screen for safety.
Open Air Installation: For installations where the
engine is operated outside, ventilation will be no
problem..However, in protecting the engine from the
elements, see that nothing obstructs the flow of air
around the engine.
The outlet of the vacu-flo scroll must not be
restricted or overheating will result. Engine
overheating can cause troubles ranging from vapor lock to scored
pistons and cylinders.