Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Perplexing radiant floor question

Dayle Member Posts: 3
We installed a flextherm radiant floor system in our new bathroom over a year ago.  We used the wires, and not the mesh roll out.  Everything was going great for over a year, then the polar vortex settled in to our area.  And slowly the floor was not heating up until one morning in Dec, it just stopped heating all together.  We called flextherm which sent out a technician on Jan. 20th.  He could not find the break using his tech, but there were zero OLM's from the wires.  He left with no resolution and said he would send a repair kit if we were lucky enough to find the break somehow on our own.  I called the tiler we used, and he said he broke a wire, "but repaired it on his own."  I asked did you soder it and replace the insulation in the wire......of course not.   But he told me exactly on the floor he "nicked" the wire.  BOOM!  Found it, the wires were burned up, i cut them out, replaced them exactly how flextherm said to do so, and tested the wires again, and I have full OLM output.  But when I put the thermostat back on, it can only get up to 62.4 degrees, and holds there.  So now I am baffled.  There are no breaks in the wires, so we are good there.  No error messages on the thermostat, so what can I do now?  Any help or thoughts would be greatly appreciated.



  • Mark Eatherton
    Mark Eatherton Member Posts: 5,840
    Homes on ohms...

    Watts up?

    Using your digital OHM meter, what exactly is the resistance, and voltage applied?

    Then you can use Ohm's law and figure out what you've got in the way of power.

    Area divided by watts times 3.41 = btu/sq ft. Should be between 20 and 30 per square as a rule of thumb rough estimate.

    Curious as to how you found and repaired the break in the grid?

    Was this poured in gyp, or staple up or?

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Dayle
    Dayle Member Posts: 3

    31.2 is the reading on the meter.

    The guy who installed the tile told me recently he broke a wire with his trowel slinging the leveler. told me exactly where it was, he just tied it back together, where it burned up.

    No staples, the wires were wrapped around orange circular braces to keep the wires down. Then leveler, glue, then tile.
  • Ironman
    Ironman Member Posts: 7,119
    edited March 2014
    Amp Draw?

    If you have a clamp around amp meter (aka amprobe) you can measure the amp draw from one feeder wire and multiply that times the voltage to get the wattage. Then multiply that times 3.413 for the btu output.

    It looks as though you're a little lean on heat cable and I doubt that the floor alone will keep up when the temp is this low.

    What your tile guy did was obviously wrong. He could have left tile out of the damaged area until it was properly repaired. I'm glad he owned up to it. Hopefully, he'll repair your tile at no cost. That would be the right thing to do.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,840
    Not enough information...

    Is that the ohms of resistance, or the applied voltage?

    And how many square feet of active radiant surface is there?

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Zman
    Zman Member Posts: 7,446

    The manufacture should be able to tell you what the normal range specs should be for your particular mat.

    The ohms need to be measured with the mat isolated from the power. The amps can be checked with an amp clamp while the system is energized.

    The best practice for these installs is to check the ohm rating before and after the install and record the readings. This catches the tile guy's mistake early in the process.

    Some manufactures will list the factory readings on the ends of the cables or in the literature provided.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Dayle
    Dayle Member Posts: 3
    Thanks for the help!

    Had the day off from school because of all the snow, so I worked all day on this. Right now I am working on finding a ground fault in one of the three open areas. 2 by Flextherm, and one by me. My bet is on me not grounding correctly. I am almost done rewiring my mess, I will respond if this fixes my problem. Thanks again!