How to Install Hydronic Tubing

Plan the Installation

• 1

  Choose a tubing installation method. Hydronic heating systems that heat flooring in homes typically are installed either in a slab on grade, in a thin layer of gypsum or concrete subflooring, or between layers of wood subflooring. Slab-on-grade installations are the most common type of installation in new construction.

• 2

  Plan the zones and tubing runs. Many suppliers of hydronic heating components offer free design services, although in many cases, it's helpful to have a professional design the system.

• 3

  Determine the locations where piping will need to penetrate the slab, for example at the slab edges or at free-floating control joints. Each of these locations will require a sleeve at least two pipe sizes larger than the tubing to be installed. PVC or ABS pipe sections are an excellent choice for sleeving hydronic tubing.

• 4

  Eliminate any joints in the piping inside the slab. Most building codes prohibit the use of joints in the piping, because repairing any leaks that might occur would require destruction of the slab.

Prepare the Slab

• 5

  Install the necessary vapor barrier, insulation and reinforcing wire in the following order.,

• 6

  Lay the vapor barrier. Vapor barrier should be installed between the ground and the slab prior to pouring concrete.

• 7

  Install the insulation. Expanded polystyrene insulation can be installed between the vapor barrier and the slab to improve efficiency, although it may not be required in all cases. The sides of the slab and footings, however, should be insulated in all cases.

• 8

  Install the reinforcing wire. Use the same techniques for installing reinforcing wire that you would use for an unheated concrete slab.

Install the Tubing

• 9

  Uncoil the PEX tubing from the roll. Ensure that the tubing comes off the roll without twisting by either rolling the coil of tubing along the ground or by suspending the coil and allowing it to unroll as you pull the tubing off of the roll. If you lay the coil horizontally and lift the tubing off of it, the tubing will come of the coil with twists and kinks.

• 10

  Lay the tubing according to plan. Most of the time, the tubing is run in parallel courses approximately 1 foot to 2 feet apart, depending upon the needed heating load. The tubing should be run parallel to the walls that are expected to lose the most heat, such as exterior walls.

• 11

  Secure the tubing to the reinforcing mesh with plastic zip-ties or the manufacturer-recommended fasteners. Do not use wire to tie the tubing to the mesh, as it may wear through the tubing and cause a leak.

• 12

  Leave plenty of extra tubing sticking out at the ends of the tubing runs, so that you can trim it to fit after the slab has been installed.

• 13

  Route the tubing through sleeves at locations where the tubing penetrates the sides of the slab. In many cases, it's easiest to route the tubing first, then install the sleeve after cutting the tubing to length. However, you need to make sure that each loop of tubing in the slab is continuous, with no joints that will be embedded in the concrete later.

Test, Pour and Cure

• 14

  Test each loop by plugging one end and pressurizing the tubing with an air compressor, then testing for leaks. If there's a leak in the tubing for some reason, it can only be repaired before the concrete is poured. Pressure testing kits can be purchased from hydronic suppliers or you can build one with a few common plumbing components and a pressure gauge.

• 15

  Pour and finish the concrete slab according to typical installation guidelines. Leave the tubing firmly attached to the reinforcing mesh so it doesn't float to the top of the slab as the concrete cures.