When the thermostat calls for cooling, the hot water pump is off. The chilled water pump moves water from the chiller tank and pumps it up a “candy cane” shaped loop and out to the air handler. See Fig. 17-4. As the water returns to the chiller tank to be cooled again, it passes through the water reservoir.
The water does not flow through the tubes of the hot water generator as it returns to the chiller tank. The water in the generator is dormant because it is plugged by a check ball. This is held in place by the pressure from the discharge side of the chilled water pump.