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[Sprinter]

I would go back to each exchanger you have and see what btu or GPM they need. 1" pex is recommended to flow 3.8-7.5gpm, PAP is 5.2-10.4gpm.  1gpm@180 supply & 160 return =10,000btuh.
Just an estimate but pool 200-300kbtu + DHW 40-100kbtu + 2 air handlers 80-120kbtu =320-520kbtuh if all zones are calling. That's a minimum of 32 GPM for 1 tap, this would max out 2" pex. If the boiler only has 2-sets of 1" taps that limits its max btu output to 160kbtuh under safe design.
What boiler model?

[muffin]

I would go back to each exchanger you have and see what btu or GPM they need. 1" pex is recommended to flow 3.8-7.5gpm, PAP is 5.2-10.4gpm.  1gpm@180 supply & 160 return =10,000btuh.
Just an estimate but pool 200-300kbtu + DHW 40-100kbtu + 2 air handlers 80-120kbtu =320-520kbtuh if all zones are calling. That's a minimum of 32 GPM for 1 tap, this would max out 2" pex. If the boiler only has 2-sets of 1" taps that limits its max btu output to 160kbtuh under safe design.
What boiler model?

CB 6048.  Thought it was rated to 500K BTUs if I remember right.

[LittleJohn]

If memory serves me correctly the largest port on the 6048 is 1.25" - about 10-12 GPM

[cando attitude]

Do yourself a big favor and read this http://www.taco-hvac.com/uploads/FileLibrary/SelectingCirculators.pdf

Great reading for anyone that wants to do things right.

Thanks for posting the link hondaracer.........indeed I found it very informative reading....would highly suggest to others looking for objective information