The tubing should be laid out evenly spaced, with all the tubes of equal length ±5%. If one tube is substantially shorter than another, that tube will have a greater water flow and the full-length tubes will have less water flow, causing uneven heat. As a general rule, place PEX tubing at approximately 3” from what will be concrete slab edge and 12” apart.
PEX Installation TIP: Divide the total area by the number of loops to be used. Space the tubing as required, filling that area with the loop serving it.
Keep in mind that concrete tends to average the temperature of the slab so that precise separation of area temperatures is not possible. All tubes should be protected at the point they enter and exit the concrete, with the pipe bend supports included. The tubes should exit the concrete directly below the RMS panel so that the tubes do not strain the manifold connections when attached.
One method of ensuring this is to make two brackets out of re-rod and drive them into the soil to hold the pipe bend supports during installation. Attached is a plan for tubing layout. It is not always possible to make a complete loop and still have enough tube to get back to the manifold. In those cases, go as far as you can with the run and still allow enough length to get back to the manifold. Fill in the area with the next loop as shown. The tubing can be installed in applications with or without re-rod. If re-rod is not used, the tubing can be attached to the insulation with the plastic anchors that are included with the tubing.
With the tubing held in place, tap the anchors down with a mallet. If re-rod is to be used, the tubing can be installed as described, using the plastic anchors and the re-rod put in place afterward; or the re-rod can be put in place first. If you put the re-rod down first, we recommend tying the tubing to the re-rod with steel or plastic wire ties instead of attaching the tubing to the insulation with plastic anchors.
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