Celotex and heat?

Discussion in 'Plumbers' Talk' started by candoabitofmoststuff, Jun 19, 2021.

  1. candoabitofmoststuff

    candoabitofmoststuff Screwfix Select

    Just had a new boiler installed... and as part of the work I had a faulty immersion heater replaced.
    Removing the old one needed a bit of "thermal persuasion", and to enable this some of the insulation was cut away from the top, as pictured...
    New Immersion Heater.jpg

    Now I know Celotex is a thermal insulator, used to stop loss of heat through walls/ceilings, so it can cope with some heat.... but will it be ok to fashion a suitable sized piece to replace what was removed from the top of the cylinder, or will the HOT, 60 degree-ish, copper top be too much for direct contact with Celotex?
    I have some 1" thick left from a previous project, so it will be easy to do!

    Thanks in advance,

  2. CGN

    CGN Screwfix Select

    I wouldn’t bother. Negligible loss.
    BiancoTheGiraffe likes this.
  3. candoabitofmoststuff

    candoabitofmoststuff Screwfix Select

    Perhaps... but I have the material to patch it... if it's safe?
  4. BiancoTheGiraffe

    BiancoTheGiraffe Screwfix Select

    Stick a bit of expanding foam on it if you're really that bothered.

    It's only 60-70 degrees, not that hot really
  5. CGN

    CGN Screwfix Select

    Im sure it will be fine
  6. andy48

    andy48 Screwfix Select

    1. I can't find an ignition temperature for Celotex but it seems unlikely to be anywhere near the maximum temperature of a hot water cylinder. I would expect the ignition temperature to be much higher.
    2. The only possible ignition source I can think of would be arcing from the terminals inside the immersion heater cover.
    3. If you do fit it, make sure it stays below the level of the brass octagon at the base of the immersion heater's black cover.
  7. candoabitofmoststuff

    candoabitofmoststuff Screwfix Select

    Thanks all.

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