UA value and primary return/air volume flow are both locked

Owned by Dennis De Beuckeleer
Dec 20, 2022
1 min read

The error message

Here you see a heat exchanger which gets this fault (note that in the case of air volume flow you are using a dry cooler, and the same comments for return temperature apply).

This is due to the definition of the heat exchanger. There are 2 options:

  1. a UA value is applied, which Hysopt uses to calculate the primary return temperature based on the secondary design flows/temperatures, the UA value and the primary supply temperature.

  2. primary flow and return temperature are filled in, which Hysopt used to calculate the UA value based on primary and secondary flow. temperature.

As you can see, Hysopt will do a calculation based upon the filled in parameters. If both return temperature and UA-value are filled in and locked, Hysopt is not able to make the calculation. Leave one of them to be calculated by Hysopt to correct this error message.