Sizing criteria of Deaerator balancing line

[ConanCake]

With reference to this thread [URL unfurl="true"]http://www.eng-tips.com/viewthread.cfm?qid=63883[/url]

About Deaerator balancing line for balancing pressure and level of both deaerators, is there any design criteria this line? sizing, general requirement, etc..

Many thanks

 

[GenB]

Best to use a full size DA and if backup is needed add another full size DA. Then isolate with auto or manual valves to change when needed.