How to Put Hot Water Heating Tubes in New Concrete
- 1). Take your foundation plans to the radiant floor heater supplier and work up a material list for the system. He will provide you with a PEX pipe layout plan showing the layout of the heating tubes.
- 2). Take the plans to the architect to ensure that there are no obstructions to the PEX plan layout. These could include step-downs in the slab, structural steel or even post-tension slab.
- 3). Direct the concrete subcontractor to include a 6-millimeter vapor barrier above the ground and a 6-inch compacted layer of gravel screenings to the foundation. Install it after the plumber and HVAC subcontractors rough in the part of the foundation.
- 4). Negotiate with the concrete subcontractor to install 4-by-6-foot extruded polystyrene insulation on top of the screenings. The rebar needs to be installed over the insulation.
- 5). Lay the PEX line in continuous loops of less than 300 feet. Start and end each loop at the location for the plumbing manifold. This is where the plumber ties the PEX pipe into the plumbing system. Follow the PEX plan for the best heating comfort after installation. PEX pipe runs 6 inches apart at the perimeter and runs 12 to 16 inches apart inside the center of the zone. The PEX pipe attaches to the rebar at 16-inch intervals. There should be 3 inches of concrete above the PEX pipe when finished. Number the beginning and end of each loop so you can tell them apart when connected to the plumbing manifold.
- 6). Attach the end of the loops of PEX pipe to a short piece of rebar about 12 inches above the concrete. Tie them to the rebar in order, spacing them about 2 inches apart. Secure them in position so that the PEX pipe will come out of the concrete 1 inch in front of the wall. Cut the PEX pipe about 36 inches above the rebar and cap the ends to keep out dirt..
- 7). Pour the concrete in the customary manner. The Pex pipe is ready to be connected to the homes plumbing.
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