We have a 2001-era Wirebo 6-loop brass radiant heat manifold that has started to leak @ the 1.25" connections. There are 2 other labels on the manifold: F877 and NSF-rfh (both appear to be standards and not model numbers).

What o-rings / gaskets are going to be optimal to replace the leaking seals? I'm assuming that I'd want to replace the gaskets on the 1/2" PEX (Wirsbo Aquapex) connections at the same time.

I'm thinking I need the one @ the link below and NOT the Truflow gasket? Also, is there a better OEM brand that would limit future leaks?

http://www.pexsupply.com/Wirsbo-Uponor-A2403232-1-1-4-Brass-Manifold-Gasket-spare-part-4583000-p