Thermostatic to Electric shower

Discussion in 'Plumbers' Talk' started by Shiam04, Nov 20, 2020.

  1. Shiam04

    Shiam04 New Member

    Hi all,

    Ive always changed like for like showers. On this occasion i changed a Thermostatic (Hot & Cold Feed) for a standard electric shower (cold feed only). So im assuming im missing something.

    I cant remember the KW rating on the old unit. And the water feed was taken from a branch off an existing pipe.

    I bought a Triton Erich 10.5KW, and for some reason its not operating as it should. I seem to get a few gentle supply of water out the hose, but no pressure or no heat. There is a HUMMMM like noise, power light is on.

    I can only assume its to do with the water pressure.

    Would it be best for me to get one that has a reduced KW rating, and one that uses for exmple 0.7bar pressure.

    Its defiantly not the new unit as i swapped it for a new one thinking the unit was faulty, but encountered the same issue.

    Any help would be great.
     
  2. terrymac

    terrymac Screwfix Select

    If your previous shower had a hot and cold feed ,it would not have been an instantaneous electric shower.
    Please give details of the electric shower circuit . The amperage rating of the MCB ,or fuse that protects the circuit.
     
  3. dcox

    dcox Active Member

    Can you confirm that the cold supply is mains and not from a tank?
     
    Shiam04 likes this.
  4. Shiam04

    Shiam04 New Member


    Hi, from what I can see it’s a branch off. Seems to be branched off from the same water supply as the toilet cistern.
     
  5. Shiam04

    Shiam04 New Member


    No it was not a instantaneous electric shower. It did have the hot feed. But I have now removed that as I’d just like to use the cold feed.
     
  6. dcox

    dcox Active Member

    How do you heat your water for your hot taps? Combi boiler or hot water cylinder?
     
    Shiam04 likes this.
  7. Shiam04

    Shiam04 New Member


    Hot water cylinder in the airing cupboard
     
  8. drety

    drety New Member

    You need to measure the pressure and check it is suitable for the new shower.
     
  9. nigel willson

    nigel willson Screwfix Select

    Turn off your mains stopcock and see if you’ve still got water at ur shower. If you haven’t theres your problem , tank fed water won’t run an electric shower
     
  10. drety

    drety New Member

    You sure.....
     
  11. jonathanc

    jonathanc Screwfix Select

    Two things need checking

    1) is the water supply from the header tank or mains ( as discussed above) and

    2) what is the design of the electricity supply: I.e. mcb rating cable size and rcd protected.

    need details on both counts from the OP
     
  12. Shiam04

    Shiam04 New Member

    measuring this tommrow with a screw on pressure gauge
     
  13. Shiam04

    Shiam04 New Member

    Id Say header tank. as its branched from the Toilet inlet

    Cable size looks about 8mm Twin & Earth grey cable. there is a trip out connected to the circuit thats rated at 30mA

    Hope this helps
     
  14. dcox

    dcox Active Member

    That shower must be fed by mains water, not tank fed. And get your wiring checked out by an electrician. It should be on a dedicated circuit with at least 10mm cable and a 45 amp breaker.
     
  15. jonathanc

    jonathanc Screwfix Select

    What is the mcb rated at? Post a pic of the cable: never seen 8mm2
     
  16. Shiam04

    Shiam04 New Member


    It’s a 10mm twin & earth. 30amp fuse
     

    Attached Files:

  17. terrymac

    terrymac Screwfix Select

    That RCD unit isnt 30 amp. It is 30 milliamp ,and if that is what your cable is connected to its not 10mm² cable.
    Your 10 kw shower is wholly inappropriate for connecting to the fused connection units in your pic. It needs to be connected to a dedicated radial circuit from your fusebox / consumer unit.
     
  18. jonathanc

    jonathanc Screwfix Select

    I had a hunch that the previous shower was one of those pump thermostatic things rather than instantaneous.

    totally agree with you, wholly inappropriate to use existing supply. Given that there are RCD FCU I would guess the CU doesn’t have RCD protection. (to the OP) post up a pic of your CU please. In which case if my guess is right there will need to be some work on the CU too
     

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