Manifold location

neophyte1

Hi all, 
  I have been reading here for a while but this is my first post. 
  I  am in the process of installing a staple up under floor system.  I am using extruded aluminum heat transfer plates on 8 inch centers with 1/2 pex-al-pex piping, 6 loops but only one zone as we are all 5 here most of the time and in most parts of the house. 
  The main design and boiler installation was done by a professional who sadly passed away very recently.  He was both old and old-school so there wasn't much on paper.  He did the heat load calculations, but I don't have them, he installed the combi-boiler and expansion tank, etc.  He set up a dummy heating loop so the combi would make domestic hot water during the install. He told me how to install the transfer plates and run the piping. He explained how to finish the system out, but the one question I have that I didn't ask before he passed was where to place the minifold. 
  Is it better to have it near the boiler, which is mounted on an exterior basement wall, or better to have it more centrally located?  The difference in this instance is only about 25 feet, but I don't want to make a mistake.  

  Thanks for any advice you guys can give. Sorry if my explanation wasn't great. 

Ironman

Locate locate the manifold as close to the ends of the tubing as is reasonably possible. That will keep the loop lengths as short as possible.

You’re probably gonna need 1” lines feeding the manifold if it has 6 1/2” loops.