Hey guys,

i have a question about the line sizing of a chiller system i am working on currently. It involves 2 V-Coil style condenser units, so basically 4 individual condenser slabs in V formations. They are to be tied together in parallel. Usually we tie them with a single copper manifold tube that runs from the first inlet to the last, with the discharge pipe going in the middle of the manifold. My question is in regards to the size of the header manifold. From past history, it was always spec'd a size larger than the discharge line. Is this a rule of thumb when it comes down to parallel headers?! I am asking because it does not really make sense to me since now you have decreased the velocity of the oil and refrigerant. Can anyone familiar with parallel air cooled condensers give me some advice on piping them together?

Thanks!
Here is a rendering of the layout:


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