Basin tap back nut size

Discussion in 'Plumbers' Talk' started by JimLow, Oct 10, 2018.

  1. JimLow

    JimLow New Member

    I’m fitting new bath and basin taps for a friend. Bath ones were fine but when I came to take off the basin ones my 27mm box spanner is too big for the back nut. It’s hard to measure up there but looks perhaps between 22 and 24mm.

    Just wondered if anyone knew of other standard size back nuts smaller than the 27mm AF size or is it a case of me having to buy a set of box spanners and seeing which one fit.

    Actually the bath ones were a bit of a pain as the tap connector nut (not the back nut) was between the 27mm and 32mm sizes of my basin wrench so had to fiddle around with an adjustable spanner up there. They were Yorkshire tap connectors not flexi ones. I was surprised that the wrench didn’t fit as i thought that is what they are for.

    Cheers

    James.
     
  2. dobbie

    dobbie Well-Known Member

  3. JimLow

    JimLow New Member

    Thanks for the reply. I’ve got one of those but the design of the basin meant there wasn’t enough room to get it far enough up to reach the back nut. I can only get it to within about 5mm of the nit and then the curve of the ceramic stops it. I’ll give it another go though.
     
  4. retiredsparks

    retiredsparks Well-Known Member

  5. dobbie

    dobbie Well-Known Member

  6. terrymac

    terrymac Well-Known Member

    Buy backnuts that your box spanner fits. Although the thread is always 1/2 inch ,on basin taps ,the nut size ( measured across the flats ) can vary . i just use a shim inside my box spanner to take up the difference when i get smaller nuts.
     
  7. retiredsparks

    retiredsparks Well-Known Member

    OP says he can get access....just box spanner wont fit .
    Could it be a very unusual size nut ?

    "the basin ones my 27mm box spanner is too big for the back nut"

    Rs
     
  8. JimLow

    JimLow New Member

    Thanks everyone.
    I do have one of those box spanners. They didn’t use flexi pipes but once disconnected (using one of these basin wrenches https://www.screwfix.com/p/basin-wr...odgS0OHw#product_additional_details_container) the pipe drops down inside the floorboards enough to slide the box spanner (like you linked to Dobbie) onto the tap pillar. However, the back nut is smaller than the smallest end of the box spanner. It seems an unusual size (perhaps designed for something else?) and just wondered if anyone else had seen this type before.
    Terrymac, the new taps have 27mm AP size back nuts (1/2” equivalent) so no problem with tightening them with my box spanner.
    Thanks
    James
     
  9. terrymac

    terrymac Well-Known Member

    So if your box spanner is too big for the back nuts on the old taps ,just put a shim into the spanner. Have you tried just spinning the tap back and forth ? You can very often loosen the back nut then by hand.
     
  10. JimLow

    JimLow New Member

    I did try spinning the tap back and forth but it didn't seem to loosen the back nut at all. I'll try adding a shim to my box spanner.

    Thanks,

    James.
     

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