TM 5-2410-241-23-1
0012
AIR CONDITIONING AND HEATING SYSTEM CONTINUED
Heating System with Water Valve Control
00012
The heating system is a water valve control type system. The control system for the water valve regulates the
amount of hot engine coolant that is circulated through the heater coil. The water valve is regulated by a
mechanical cable.
The hot coolant from the engine circulates through the heating system. This coolant flows from the outlet valve of
the engine cooling system (Figure 8, Item 1), through the heater control valve (Figure 8, Item 4), through the heater
coil (Figure 8, Item 2), and back to the return valve (Figure 8, Item 3) for the engine cooling system. The
temperature control knob, which is located on the control panel within the cab, regulates the flow of coolant.
With the temperature control knob in the maximum cold position, the heater control valve (Figure 8, Item 4) is
closed. This prevents the flow of coolant into the heater coil (Figure 8, Item 2). When the control knob is moved
away from the maximum cold position toward the maximum heating position, the heater control valve begins to
open. As the control valve opens, coolant begins to flow from the outlet valve for engine cooling system (Figure 8,
Item 1) through the heater control valve and into the heater coil. As the hot coolant flows through the heater coil,
the temperature of the air that is flowing through the coil increases.
The temperature of the air that is flowing out of the heater coil (Figure 8, Item 2) and into the cab is controlled by
the amount of coolant that circulates through the heater coil. The coolant transfers the heat into the air stream. By
increasing the amount of coolant that is circulating through the heater coil (Figure 8, Item 2), the temperature of the
air that is flowing out of the coil also increases. The coolant leaves the heater coil at a reduced temperature and
flows back into the return valve (Figure 8, Item 3) for the engine cooling system.
Figure 8. Heating System.
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