Repair a Non-Working Radiant Floor
Kevin O'Connor advises on how to hunt down the break
The heated electric floor in our tiled kitchen no longer works. Is there a way to locate a break in this kind of wiring so it can be repaired? — Russ Blinco, via e-mail
Have you asked an electrician to make sure there's no other problem with your floor-heating system? If so, master electrician Scott Caron, owner of Caron Electric and a regular guest on Ask This Old House TV, says it is possible—but not easy—to find a break in hidden wires and repair it.
The trick is to use a device called a tone generator and probe. The generator clips to the wire you want to trace. The probe emits a ringing tone when it's directly over a buried but unbroken wire, then goes quiet where there's a break. "You can buy one at a home center for about $40," Caron says. You'll also need to get a wire-splicing kit from the company that made your system. "Look for the manufacturer's name on the thermostat," Caron says.
Clip the generator to one of the floor-heating wires in the junction box, where the heating system connects to the house wiring. Then use the probe to trace that wire as it zigzags back and forth under the tile. Focus on places where the wire would likely have been cut and, Caron says, "with a little luck and a lot of patience, you should be able to find the break."
Now carefully chip out the tile, without damaging any more wires. (Find the how-to for removing a tile.) After you splice the faulty wire, but before you lay a new tile, turn on the floor heat. If it works, congratulations! If not, you'll need to hunt down another break.
— This Old House host Kevin O'Connor