The first method has more extensive pipe works. But the water side flow control is
easier and there is less pressure drop. Globe valves may be needed to ensure
sufficient flow rate. Check valves are not required.
Due to the header pipes in the second method, check valves are needed for each
chiller. Globe valves or balancing valves are also needed for each chiller for water
balancing. All the pumps will operate in parallel and a higher water pressure drop is
expected. Furthermore, balancing valves are also required in each circuit of the fan
coil unit for proper balancing of the entire coil.
Nevertheless, if any one of the chiller is OFF, the second method will always allow an
even water distribution to the whole heat exchanger in the fan coil unit. In the first
method, hot air will by-pass through the portion of the coil which the chiller is OFF.
Section 2 Page 23
To Next Page
Loading...
