841349 Volvo.Penta Cylinder block

Circulation of Coolant
Illustration 1 g00883536
Schematic of the coolant flow
Upon energizing the heating system, coolant is drawn from a low point in the engine's cooling system. The coolant is circulated by a centrifugal pump through the heating tank. The coolant exits the tank through a switch that senses the fluid flow (flow switch). The heated coolant is pumped to the top of the engine. The coolant flows downward through the engine for recirculation.During engine operation, a solenoid valve at the heater's outlet limits the coolant's backflow. The solenoid also limits the backflow when the heating system is shut down.Circulation of Lube Oil
Illustration 2 g00883468
Schematic of circulation of lube oil
Upon energizing the system, engine oil is drawn from the engine oil sump. The engine oil is circulated by a gear pump through the heating tank. The heated engine oil exits the tank through a switch that senses the fluid flow (flow switch). The engine oil is routed back to the engine oil sump for recirculation.A check valve at the heater's outlet limits the backflow when the heating system is shut down.Electrical System Operation
Illustration 3 g01365810
Operational schematic of the electrical system
(1) Customer supplied circuit breaker
(2) Fuse
(3) Transformer
(4) Control relay
(5) Control box's on/off switch
(6) On/off indicator
(7) Solenoid
(8) Time delay relay
(9) Coil for the pump motor's contactor
(10) Pump motor's contactor
(11) Pump motor's protective switch
(12) Pump motor
(13) Flow switch
(14) Pump motor's protective switch's auxiliary contacts
(15) Thermostat
(16) Coil for the heating element's contactor
(17) Heating element's contactor
(18) Heating element Note: Except for the few differences that are noted, the jacket water heater and the lube oil heater operate in the same manner. In combined heating systems, the jacket water heater and the lube oil heater can be operated independently.The requirement for voltage and frequency depends on the particular system. The different systems require 380 to 480 volts and 50 or 60 Hz.Customer supplied circuit breaker (1) protects the system from electrical overload. The 380 to 480 volts are provided to transformer (3), to pump motor (12), and to heating element (18).Note: The fuses at the different locations have different ratings.Fuses (2) protect transformer (3) from electrical overload.Although the pump motor and the heating element require high voltage (380 to 480 volts), the heating system's control is powered with lower voltage. Transformer (3) reduces the high voltage to 110 to 120 volts in order to operate the system. After the transformer, fuse (2) protects the 110 to 120 volt system from electrical overload.Before the system can be operated, control relay (4) must close the circuit. The control relay is operated via customer supplied 24 volts. The control relay opens the circuit during engine operation and the control relay closes the circuit when the engine is shut down.When on/off switch (5) on the control box is switched, the system is powered up and indicator (6) on the control box illuminates.Note: Solenoid (7) is only installed on the outlet for the jacket water heater. The solenoid valve limits the coolant's backflow. The lube oil heater has a check valve which limits backflow.Time delay relay (8) is normally closed. The relay enables voltage to energize coil (9). The coil's magnetic field closes magnetic contactor (10). Closure of the contactor allows high voltage through protective switch (11) to pump motor (12) in order to circulate the fluid for heating.Protective switch (11) protects pump motor (12) from two conditions: electrical overload and thermal overload. If either condition occurs, the switch opens in order to remove power from the pump motor. The pump motor's protective switch must be reset before the heating system can be restarted.Flow switch (13) is installed at the heating tank's outlet. Upon every activation of the heating system, the flow switch activates time delay relay (8). If proper flow is not established, the time delay relay shuts down the entire heating system according to the delay time. During the time delay, the pump continues to operate in an attempt to restore the flow.The time delay is adjustable from 0 seconds to 180 seconds. For initial start-up, the maximum of 180 seconds is recommended in order to allow the pump to establish the fluid flow. For subsequent operation, the recommended setting is 30 seconds.After the fluid circulates through the heating tank, the fluid passes through the flow switch. The established fluid flow closes the flow switch. Closure of the flow switch enables voltage through the pump motor's protective switch's auxiliary contacts (14) and through thermostat (15) to energize coil (16). The coil's magnetic field closes magnetic contactor (17). Closure of the contactor allows high voltage through fuses (2) to heating element (18). The element heats the fluid that circulates through the tank.If the fluid flow is interrupted, the flow switch immediately opens and the circuit for coil (16) is interrupted. Magnetic contactor (17) opens and the high voltage is removed from the heating element. The time delay relay is activated again. Unless the fluid flow is restored within the delay time, the time delay relay shuts down the entire heating system.Auxiliary contacts (14) provide a redundant shutdown for the heating element. If the pump motor's protective switch opens, the auxiliary contacts also open in order to interrupt the circuit for coil (16).Thermostat (15) is located at the inlet to the heating tank. If the fluid's temperature exceeds the thermostat's rating, the thermostat's switch opens and voltage is removed from coil (16). Loss of the coil's magnetic field opens contactor (17). The high voltage is removed from the heating element. The pump motor will continue to operate. When the temperature of the fluid is reduced below the thermostat's rating, the thermostat's switch closes and power is restored to the heating element.Note: In addition to the thermostat at the inlet to the heating tank, the lube oil heater's element also has a backup thermostat for a high limit. If the primary thermostat is faulty and the heating element exceeds the backup thermostat's rating, this backup thermostat removes power from the heating element. This prevents the lube oil from overheating.The automatic shutdowns protect the heating element