Using PEX for the first time.

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Old 09-25-15, 05:24 AM
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Using PEX for the first time.

I am going to be replumbing a house using PEX (replacing metal pipes). I know that PEX is flexible and can turn corners, but how tight of a corner can it turn? When is it time to use a elbow?
Thanks in advance for the info.
 
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Old 09-25-15, 05:55 AM
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You'll know right away. It wasn't as flexible as I thought.
 
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Old 09-25-15, 06:11 AM
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The minimum bending radius for PEX is 8 times outer diameter, so:

1/2 (ID Nom.) PEX bending radius is 5"
3/4 PEX 7"
1 PEX 9"

It can be difficult to achieve those minimum values without a bend support; I've found the "natural" bend radius is somewhat higher.

Part of the benefit of using PEX is minimal need for fittings like 90s and 45s, which has benefit of fewer chances for leaks, and higher flow rates. So one generally tries to avoid using fittings when possible. This does take some getting used to and planning to allow space for more gentle curves. But it quickly becomes second nature. An example: When running PEX along side of a joist, and you need to route it into the next joist bay, you drill the hole at a 45 instead of a 90 so the tubing just makes two gentle bends. Good luck with your project.
 
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Old 09-25-15, 06:16 AM
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Most stores that carry pex have plastic & metal elbow forms you snap the tubing into. They form about a 4" radius and are not really necessary in most cases but are handy in tight spaces or when you need to secure the bend to a stud.
 
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Old 09-25-15, 06:21 AM
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Thanks guys, that was most helpful.
 
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Old 09-25-15, 08:30 AM
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In the end I think you'll find that many/most of your bends can be made by bending the tubing. And it's better for flow if you bend the tubing instead of using fittings as the fittings go inside the tubing and reduce the inner diameter in addition to the flow loss for a sharp 90 degree.
 
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