Onan 25.0 DEH-53R Series Operator's Manual And Parts Catalog page 16

C O O U N G S Y S T E M
Standard Radiator Cooling, uses a set mounted
radiator and engine driven pusher type fan to cool
engine water jacket. Air travels from the generator
end of the set, across the engine and but through the
radiator. An integral discharge duct adapter flange
surrounds the radiator grille.
Heat Exchanger Cooling (optional), uses a shell and
tube type heat exchanger instead of the standard
radiator and fan. Engine jacket coolant circulates
through the shell side of the heat exchanger, while
raw cooling water is pumped through the tubes.
Engine coolant and raw water do not mix. This type of
cooling separation is necessary when the raw water
contains scale forming line and other impurities.
This system reduces set enclosure airflow ahd noise
levels. Proper operation depends upon a constant
supply of raw water for heat removal. The engine
coolant side of the system may be protected from
freezing the raw water side cannot. See Figure 8 for
typical installation.
c
EXPANSION
' TANK
^
HEAT EXCHANGER
• ~ - r n ENGINE
FROM
ENGINE
J
DRAIN
SOLENOID
V A L V E
(OPENS WHEN.
SET IS RUNNING)
7"
A D J U S T A B L E
V A L V E
( R A T E O F FLOW) e x
R e v .
JTwATER
IN
S T R A I N E R
F I G U R E 8. T Y P I C A L HEAT E X C H A N G E R S Y S T E M
Siandpipe Cooling (optional) substitutes a mixing
(tempering) tank for the standard radiator and fan.
Cooling watercirculating through theenginejacket is
mixed with raw water in the tank. Because raw water
flows through tho engine jacket, it must not contain
scale forming .impurities or fouling of the engine,
water will occur. Fouling results in engine
overheating and ^ostiy repair bills.
This system reduces set enclosure airflow re-
quirements and noise levels. Proper operation is
dependent on a constant supply of cooling water.The
system cannot be protected from freezing. See Figure
9.
ANTI-SIPHON —I
SOLENOID V A L V E
(OPEN WHEN
SET IS RUNNING) -
N
STAND
P I P E
WATER
IN
DRAIN
: FROM
ENGINE
TO ENGINE
A D J U S T A B L E V A L V E
( R A T E OF FLOW)
STRAINER
F I G U R E 9. TYPICAL STANDPIPE SYSTEM
Remote Radiator Cooling (optional), substitutes a
remote mounted radiator and an electrically driven
fan, for the set mounted components. Removal of the
radiator and fan from the set reduces set enclosure
airflow requirements and noise levels without forcing
dependence on a continuous cooling water supply.
The remote radiator system can be completely
protected against freezing.
This system must be designed to meet specific
requirements of the application.
Water Jacket Heater (optional) may be installed to
keep engine coolant warm while engine is shutdown.
It heats and circulates the coolant within the engine,
which reduces start-up time and engine wear caused
by cold starts. It is electrically operated and. ther-
mostatically controlled.