How to Install Hydronic Heat in a Sidewalk

Set up the base, or substrate, as for an unheated walk. Compact 5 to 6 inches of gravel for concrete or the same depth of sand for pavers or stone. Pack the substrate down firmly with a tamper and level the surface with a 2-by-4 board. If possible, allow the substrate to settle overnight before leveling it.

Turn 2-by-6 inch lumber upright on their sides along the edges of the walk for framing to contain the wet cement. Use a mallet to pound in 2-by-2 inch stakes approximately every 18 inches along the outside of the framing to support it. Line walkways made of stone or pavers with edging stones.

Cover the gravel substrate for cement walks with reinforcement mesh.

Lay out a system pattern of loops with spray paint on the substrate. Your specific layout will depend on the size and manufacturer of your heating system. Tubing comes in one-circuit lengths so leave enough extra length on each circuit to reach the manifold, the brass connection that manages the connections of each circuit to the boiler.

Place the tubing on the reinforcement mesh or pour sand along the pattern painted on the substrate. Connect tubing to the mesh with connection clips and galvanized nails and link the tubing with brass connectors. Protect any sharp turns with aluminum guards to keep the tubing from kinking. Connect the circuits through the manifold or directly to a pressure test kit.

Connect a pressure test kit up to the manifold and inflate the coils to 100 pounds per square inch (psi) or another pressure required by local code to test the connections and find any leaks. Run the test for 24 hours or as long as mandated by code: the pressure should not vary by more than 10 psi throughout the test.

Pour concrete or set the pavers carefully on top of the substrate. Re-test the connections periodically, as you work, to ensure that no leaks develop. You can see leaks bubbling up out of concrete, but you must use the pressure gauge signal on walks laid with pavers or stones. Repair any leaks as you find them.

Smooth and level the walk. Finish the cement with a steel float as water seeps up to the surface and brush sand between pavers.

Disconnect the pressure test kit and connect the manifold to the boiler. Installing a boiler system requires a permit or, at the very least, a certified inspection of the work so have a plumber or heating specialist install it. Purging and starting up the system is part of a professional installation.