Chill water valve arrangement
Our air handlers' chill water valves (under building controls) are all configured as bypass regulators. That is, when the controls send a 100% signal, the valves squeeze off the bypass, and 0% opens the bypass. This doesn't give us complete control. I estimate that when set to 0% valve position, we still get about a 15% flow through the coil. There is a balancing valve (manual op) in the bypass, but it doesn't seem to give us any less coil flow than 15%.
There are many times/situations where we really need 0% flow and I have to run around manualling isolating the coils to keep the chill water circuits from adding unwanted heating or cooling during the temperate months.
Is this typical design? If so, why and what can be done to obtain complete positive control through the controls system?