I am pumping chilled water thru a heat exchanger and need to control the flow rate. My flow circuit has a modulating three-way diverting valve that can direct all the flow thru the heat exchanger, all the flow thru a bypass around the heat exchanger or it can divide the flow between both the bypass and the heat exchanger. I am concerned that the way I have plumbed it might not provide good flow control.
The chiller supply line enters the 3-way valve at inlet port A. Valve outlet port B runs to the heat exchanger inlet and valve outlet port C tee's into the line which runs from the heat exchanger outlet to the chiller return line.
I think I may need a needle valve or orifice in the bypass line to ensure that the pressure drop thru the bypass line is always greater than that thru the heat exchanger. I am fearfull that when the 3-way valve is splitting flow between the heat exchanger and bypass that the pressure will equalize across the heat exchanger and I will lose flow thru it if there is little or no pressure drop in bypass line. This is because the bypass connects to a common return line rather than using a separate return line. I don't want to add a second return line but wish to find a way for this general arrangement to function.
Any advice would be greatly appreciated.
Thanks, Dave Miller