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Running a feed to manifold

nickybotz Member Posts: 27
So I have to feed a manifold on the 2nd floor of my house with 1" pex. I have the basement floor ready to be poured all the radiant loops installed,. Is it a bad idea to run my 1' feeds to the 2nd floor in that slab to avoid drilling about 50 joists? Is this a bad idea ? Am I asking for trouble in the future . I can't see any reason not to I mean there's already 1000' feet of 1/2" there I don't see an issue doing it so I figured I'd ask the pros?


  • Larry Weingarten
    Larry Weingarten Member Posts: 2,543
    Hi, I'm not the right kind of pro, but do like being able to maintain things. So, how about putting in conduit you can then pull the PEX through? It could be large conduit if you insulate the pipe first, but I've had good luck doing just that. ;)

    Yours, Larry
  • RetrosPex
    RetrosPex Member Posts: 56
    I would not do that. I've had friends who have done things like drilled into a slab a couple years later, and hit a tube. It creates a huge mess. There is always the risk that will happen, but running your 1" feed upstairs through there could just compound the issue. Get a good bit, and drill away. I have gotten in the habit of making a simple template with a piece of plywood that I can line up against a nearby wall or something, so all the holes are as straight as possible. Sometimes you just have to go around obstacles though. Good luck.
  • hot_rod
    hot_rod Member Posts: 16,272
    There will be some heat loss as it crosses the concrete, sleeving it would help. It's not uncommon to pex to remote manifolds in large slabs.

    Foam type pipe insulation really causes the pex to float out of a pour, tie it well if you go that route, it will be a over a 2" diameter if you insulate, so keep it down below the slab pour or you may get "road map" cracking over the tube..

    Or, a good angle drill and a sharp new bit at least 1-3/8" diameter hole for bushings to fit in.

    Beware of where in the joist you drill a large hole, use an online hole chart to avoid weakening the framing.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream