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Varying water pressure/flow

Discussion in 'Plumbing and Central Heating' started by wobbly2, 14 Aug 2021.

  1. wobbly2

    wobbly2

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    I recently moved into a mid-sixties bungalow that seems to have widely varying water flow at kitchen taps and bath tap manual mixer hand-held shower. This is noticeable on both hot and cold.

    The bungalow has a Glow Worm 30 CSI combi-boiler that has had a history of problems but is currently working OK, least ways it gives good DHW and CH temp.

    Typical static mains water pressure is between 1.5 and 4.5 bar, usually between 4 to 4.5 bar. It rises to over 6 bar when a tap/valve is closed quickly, with the peak being even higher. Typical, dynamic (?) pressure is between 0.5 bar (bath/kitchen taps full on) to 2.5 bar bathroom sink full on and bath mixer partially on. Flow rate at kitchen sink about 17ltr/min at 1.5 bar (1700ml in 6 seconds).

    The main issue is with the bath tap manual shower mixer. After opening the bath tap and setting the flow (usually cold in my case) required for the shower then depressing the collar to divert water to the shower the shower works ok. However, the flow from the shower will frequently fall and the unit will revert to the bath tap outlet. If I then open the bath tap further and reset to shower outlet the flow after a short while will suddenly increase spraying water all over the bathroom if I don't have a good grip of the shower head.

    A similar thing happens with the bathroom and kitchen sink taps; set either to the flow required then often after a short while of use, the flow will fall to a dribble then after opening the tap further the flow will suddenly rise to weigh more than is wanted. With the bathroom sink taps this causes the water to flood over the front of the sink and onto the floor, though I have restricted flow to these taps by partially closing their isolation valves.

    I assume the problem is due varying mains water pressure. If this is the cause will fitting a PRV to the mains inlet, set to a lower pressure, reduce the problem? If not, what else could be causing the issue and how would I stop it?
     
    Last edited: 14 Aug 2021
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  3. wobbly2

    wobbly2

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    I mentioned the boiler because it occasionally gives a dribble of water from the area of the cold water inlet to the DHW heat exchanger. However, hopefully an engineer has fixed this.
     
  4. Gasguru

    Gasguru

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    Are you on a shared main with a few other properties?....what's the pressure/flowrate like at 2am etc ie. when you're likely to be the only one using water.
     
  5. wobbly2

    wobbly2

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    I don't know if it's a shared main but the bungalow is the first property in a small cul-de-sac with 4 other bungalows of which all are occupied by couples, 4 of those being retired (if that makes any difference) so no big households. I'll have to check the pressure/flow at the time you suggest.
     
  6. wobbly2

    wobbly2

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    Water board say it is not a shared main.
    The pressures at 2:00 am were:
    • 6 bar static after turning flow off quickly
    • 4 bar static after turning off slowly
    • 1.6 bar with full flow at kitchen sink
    • 1.5 - 2.3 with partial flow at bathroom sink depending how much tap was open.
    • Flow rate seemed high and possibly higher than previously stated but I forgot actually test it; sorry brain doesn't work to well at 2:00 am.
    If I need to check the flow rate again let me know.
     
  7. wobbly2

    wobbly2

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    Flow rate remained the same at 17ltr/min at 1.6 bar.
     
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