26 Generac®Power Systems, Inc.
6.3 COOLING AND VENTILATING AIR
It is absolutely essential that an adequate flow of air for
cooling, ventilating and engine combustion be supplied
to the generator set. Without sufficient airflow, the
engine/generator quickly overheats. Such overheating
can cause serious operating difficulties and also may
cause fire and personal injury. The installer must make
sure that sufficient air is available to the generator for
cooling, ventilating and combustion. The installer also
must provide for a path for exhausting the cooling air to
the exterior of a compartment, if so equipped.
Never use discharged cooling air for heating or
permit such air to enter the vehicle interior. This
air contains deadly carbon monoxide gas and
other poisonous, flammable or explosive gases.

6.3.1 GENERATOR AIRFLOW

Engine operation drives cooling fans for the two-stage
cooling air system. A pressure fan draws cooling air into
the top of the generator (Figure 2.9). This airflow cools
the engine/generator and electronic components. The
second part of the cooling system, a suction fan, draws
air that is heated from a hot engine into a collector pan
at the base of the unit. This heated air (although cooler
than exhaust muffler) is then deflected out the bottom
toward the ground.

Figure 6.9 – Airflow Through Engine/Generator

6.3.2 COOLING AIR IN LET OPENINGS

The minimum size of the air inlet opening, whether the
generator is housed in a conventional compartment or
not, is at least 100 square inches (see Figure 2.10).
This rule applies whether inlet air is brought in through
an opening in the compartment door, an opening in the
vehicle skirt, through ductwork, or by any other means.
NOTE:
Screening, louvers or expanded metal that cover air
openings restrict airflow. You must compensate for
this by making the actual air opening proportionate-
ly larger. See Section 2.3.3 (Page 27).

Figure 6.10 – Air Inlet in Compartment Door

NOTE:
Be sure to meet the minimum clearances illustrated
in Figure 2.4 (Page 23).
When the unit is installed on a suspended mounting
system, one of several different methods of supplying
airflow may be used as follows:
• Provide a door in the vehicle skirt having an air inlet
opening (Figure 2.11).

Figure 6.11 – Suspended Mount: Inlet Door

• Using ductwork (Figure 2.12, Page 27). The installer
must be sure air is available to the top of the genera-
tor since air inlets are located at the top.
• By providing an opening in the vehicle skirt and space
behind the generator for cooling airflow (Figure 2.13
Page 27). Recommended clearance behind the back
of the generator is at least 1/2 inch (13 mm).