In heating priority mode, the heat pump is controlled in response to the heating load, and the LHWT is the controlled parameter.
If condenser water flow is constant, the LHWT will vary, based on the amount of heat rejected to the condenser.
To maintain a consistent LHWT, the tower-water temperature must be artificially held at an elevated temperature, which penalizes the chillers' efficiency whenever the potential for lower tower water temperature exists.
However, the LHWT cannot be controlled by the machine while operating in the cooling priority mode, because the cooling load will vary, causing the heat production to vary.
LHWT and/or LCHWT can be maintained if variable primary water flow is used on the water loop(s).
If the heating requirement is insufficient, the LHWT will rise uncontrollably until the heat pump shuts down.
Regardless of the system arrangement, there will always be design setpoints for the LHWT and LCHWT, even if the chilled water is not produced for beneficial use.