FOR MANIFOLD SUPPORT ISSUES: 

We’ve used manifolds from Safelink/Mr. PEX for several years.  They won’t sell parts directly to a homeowner.  Here are some links to potential online suppliers who will:

House Needs - http://www.houseneeds.com/shop/atop/radiantheatingindex.asp

PEX Supply - www.pexsupply.com

Blue Ridge Company - www.blueridgecompany.com