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Twin Impeller Shower Pump

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Ref. Grundfoss STP-2.0B twin impeller shower pump. 2.2 Amp. 510 Watts. 240 Volts.


Will this pump be o.k. run through a B6 M.C.B. or will it trip the B6 on starting do you think?


Thanks,


Z.
  • 0
    That's a positive head pump, think twice if you are supplying it.

    Is the tank considerable higher than the shower outlet and is it a thermostatic mixer shower?

    If the answer is no and yes, fit a negative head shower pump.
  • 0
    I would have thought a generic pump motor would have a start up current up to 8 times the full load current. On the surface it may not trip as its below the instantaneous tripping current rating of the MCB. However, I have seen 2 times 300W lighting transformers take out C6 breakers. So perhaps I'd rate the MCB for this particular job at C6.


    Legh.
  • 0
    Instructions here say 5A fuse in plug or fused spur, so 6A breaker should be fine.  These are normally induction devices not brushed  so I'd be surprised if it was capable of popping a B type if it was the only load. (the friskeist  B6 in spec. would be instant trip at 12A, and never more than 30A. ) I'd be less happy if you tell me the 6A breaker is also supplying lights for the whole floor as well :D . (though I have seen it done)

    Equally, as above  a C6 would be the get out of jail card if it is.

  • 0

    Sparkingchip:

    That's a positive head pump, think twice if you are supplying it.

    Is the tank considerable higher than the shower outlet and is it a thermostatic mixer shower?

    If the answer is no and yes, fit a negative head shower pump. 




    A plumber has supplied the pump. I am only concerned with the electrics Sparkingchip. But thanks for the advice.


    Bye,


    Z.

     

  • 0
    If the pump doesn’t turn itself on the customer and plumber will also certainly assume it is due to a wiring fault due to poor workmanship on your part, rather than poor plumbing or the wrong choice of pump.
  • 0

    Legh Richardson:

    I would have thought a generic pump motor would have a start up current up to 8 times the full load current. On the surface it may not trip as its below the instantaneous tripping current rating of the MCB. However, I have seen 2 times 300W lighting transformers take out C6 breakers. So perhaps I'd rate the MCB for this particular job at C6.




    My rule of thumb, gleaned from manufacturers' data is a start-up current of 6 x full load. I agree with C6.

  • 0
    Why not a B16 at the consumer unit feeding a 1.5mm t&e circuit and a switched 5-amp fused connection unit to provide the final connection to the pump flex and provide local isolation?


     Andy
  • 0

    Sparkingchip:

    Why not a B16 at the consumer unit feeding a 1.5mm t&e circuit and a switched 5-amp fused connection unit to provide the final connection to the pump flex and provide local isolation?


     Andy 




    Normally a good idea for a "power" circuit, but in this case it is just not possible due to the location of the new shower pump on the ground floor in an outside "coal shed".


    Z.

  • 0
    Although if you're following the manufacturer's instructions to the letter - "The unit must be connected to a switched spur fused at 5A" (my emphasis) there seems little advantage to messing about with a lowish rated MCB.


    Presumably the FCU could be located near the CU rather than the pump (provided it can be locked off of course).


       - Andy.
  • 0
    Hello Sparkingchip. The plumber has already erred by not planning the correct system for the shower, or it may have been the customer through lack of thorough planning and forethought. All of my previous work for this customer has been spot on and works perfectly. If the pump misbehaves I will be forgiven and not locked into the stocks. The shower's water flow was inadequate so the new pump is a bolt on addition to try to rectify the problem. The water works have nothing to do with me.


    Andy, the supply for the new pump had only a B6 protected electrical supply at its location, as running a new supply is very difficult and has not been anticipated, so I am praying that it will be adequate. If not I will fit a C6 M.C.B. at the consumer unit.


    Z.

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