Underfloor heating problems - faulty thermostat?

Discussion in 'Tilers' Talk' started by mike pcs, Dec 30, 2009.

  1. mike pcs

    mike pcs New Member

    Guys, a quickie if i may. Maybe this should be posted under electricians section, but anyway..

    Fitted a wire mat UFH as part of a tiling job. Tested the resistance before, during and after fitting and all ok (36 ohms approx). This works out fine considering 240v with 8m sq of 200 watt per metre matting (6 amp or so anticipated load).

    Anyway, connected up to the rcd and it tripped. Once i disconnected the floor probe from the thermo it didnt trip...but the UFH doesnt warmup, even though the thermo is programmed for time and heat etc. To confirm, the mat is connected to the thermo, but the floor probe is now disconnected as it trips the rdc (and the mcb in the consumer unit) when the thermo is powered up. With the probe circuit connected when i "test" the rcd for the heating, the rcd trips, as does the consumer unit mcb. With probe circuit disconnected and i test the rcd, only the local/ufh rcd trips.

    This was a supplied UFH mat and thermo (from Wickes!).

    Anyway, has anyone come across a faulty thermostat before? The floor probe meters fine, as does the UFH mat. I have yet to directly wire the UFH to the mains, bypassing the thermostat (no access til next week as cust away now)to check it warms directly.

    If its a faulty thermo, fine, ill change it. The mat meters fine so it shouldnt be that (fingers crossed - its all tiled up now).

    Question is, is there a way to test the thermostat (digital - usual thing)as i suspect its the thermo at fault so far. I am quite familiar with circuitry and meters etc but cant find any internal wiring/switching diagram for the thermo


  2. tic tic

    tic tic New Member

    if all ok during instalation sounds like faulty thermostat, but i would defo post in the sparks forum mike.

    i dont mess with elect and water leave that to the boys.
  3. I know Best

    I know Best New Member

    sounds like you * the job up. that will teach you not to meddle with trades you know nothing about

    [Edited by: admin]
  4. mike pcs

    mike pcs New Member

    Tic tac, was what I was thinking.

    I know best - yeah, thanks for the useful insight.

    Having installed UFH many times without an issue (in the same way etc)I wouldnt have expected this to be an issue.

    So, not to mess with things I know nothing about? Tell you what, next time I tile over UFH I will have "I know best" there at all times to meter after I lay every tile. I'll prime the customer to pay for his/her time to sit there with his/her flashing light thingy - and massage my ego by telling me "everythin's OK, son, carry on with the next tile, there's a good boy".

    If we were all experts in every associated action with our professions we wouldn't need a forum, would we? Hold on - Maybe forums are here to make some of us feel better and where one can exhube superiority.

    "I know best". See you registered 29th Dec 09. Get a new PC for xmas?

    Thanks for the replies guys


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