2008/12/08 Caterpillar

Generator Set:

3508 (S/N: ZAB1-UP)

3508B (S/N: ZAD1-UP)

3512 (S/N: ZAF1-UP; YAK1-UP)

3512B (S/N: ZAH1-UP; YAM1-UP)

3512C (S/N: SBG1-UP)

3516 (S/N: ZAL1-UP; YAS1-UP)

3516B (S/N: ZAP1-UP; PBR1-UP; YAT1-UP)

3516C (S/N: SBJ1-UP; SBK1-UP)

A new jacket water heater is available for 3500, 3500B, and 3500C generator sets. The new heater is 480 V three-phase AC voltage. Unlike the heaters that transfer heat via the convection of jacket water, the new heater utilizes a pump in order to circulate the jacket water.

The pump allows the heater to operate at a higher wattage and with greater efficiency. The continuous circulation of the coolant results in a lower peak temperature for the coolant. Degradation of heater hoses, seals for the engine, and heating elements is reduced by the lower peak temperatures.

The new heating system exceeds the requirements of ratings for low ambient temperatures. In comparison to convection heaters, the new system can save the customer in excess of 30 percent of the electrical costs that are associated with heating the jacket water.

Note: The new heating system enables the use of heavy-duty air cleaners for 3500 Generator Set Engines. The heavy-duty air cleaners were not previously available for these packages with jacket water heaters. The 3508 high voltage package with heavy-duty air cleaners is the only package that is incompatible with this heating system.

The new jacket water heater includes the following features and benefits:

• Hoses, a pump for circulation of the coolant, and isolation valves are provided with the new jacket water heater.

• Mounting the heater to the base frame minimizes vibration that is induced by the engine.

• The heater is automatically disconnected when the engine is running via the relay for the generator space heater.

• The heater is supplied with UL® recognized components.

• The jacket water heater provides uniform heating for the entire cooling system.

• Reduced outlet temperature from the jacket water heater extends the life of the hoses, the coolant, and the heating element.

• The new heater reduces the operation cycle of the thermostat by 50 percent.

Illustration 1	g01624896
Left side view (1) Pump (2) Heater (3) Control box

Refer to Special Instruction, REHS3424, "Replacing the Convection Jacket Water Heaters with the 325-6250 Jacket Water Heater Gp on 3500 Generator Set Engines" for a complete parts list, for the electrical requirements, and for installation instructions.