hot water pressure

Discussion in 'Motorhome Chat' started by electricscott, Sep 19, 2012.

  1. electricscott

    electricscott Funster

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    had to replace the water pump and during our recent holiday the hot tap started to drip and on our last day the hot pipe in shower whale mixer valve came clean out of its housing (including the brass ferrel).
    my is question is is there an increase in pressure from the boiler when the water is hot as water will flow for a short while without the pump?
    the new direct replacement water pump has a slightly higher pressure e.g. 20psi from 16psi and my concern is will it happen again as in my view the pipe connection to the whale valve is poorly design.
    i got the following reply from whale:
    "Thank you for your enquiry. The new pump which cuts out at 2bar will have no effect on the mixer Sir. Only excessive pressures above mains pressures would cause issues for caravan equipment. Unfortunately the brass inserts cannot be replaced therefor eyou will need to replace the mixer unit completely. The part number for the Elite mixer shower is MT0140B and you can order this through any of the below retailers:”
    on the face of all should be well, except if the boiler causes excessive pressure.
     
  2. Snowbird

    Snowbird Funster Life Member

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    Have had this problem on RVs. To remedy it I used to switch the pump off and open a hot tap whilst the boiler was warming up. Once the water is up to temperature turn tap off and switch pump back on. Its the water expanding when hot.....it has to go somewhere.
     
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  3. normanandsue

    normanandsue Funster

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    As one who is slow on the uptake regarding things mechanical and electrical how do you switch the pump off? My mh does not have a separate isolation switch for the pump or the lights, just a master switch. Would this mean, at night, plunging mh into darkness whilst I wait for the hot water to heat up?

    Norman
     
  4. Snowbird

    Snowbird Funster Life Member

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    Having owned more motorhomes than I can remember I have never had one that didn't have a switch for the water pump, so am afraid I cant help in that matter.
     
  5. Terry

    Terry Funster

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    Have a look at your control panel, you prob have one :thumb:
    You will be in the dark a long time, boiler will not work with power off
    Terry :Wink:
     
  6. electricscott

    electricscott Funster

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    what a useful piece of advice, :thumb: many thanks snowbird
     
  7. pappajohn

    pappajohn Funster Life Member

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    what make and model is the water pump ?

    the boiler should have an expansion area (free space) at the top to counter the effect of hot water expansion, the air gets compressed as the water expands....just as a sealed domestic boiler (combi) has an expansion tank.

    regardless of what whale have said, I reckon a 2bar (28psi) cut-off pressure is too high for the system.
     
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