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Discuss Poor pressure from kitchen mixer tap in the Plumbing Forum area at

  1. Fruitbat04

    Fruitbat04 New Member

    Afternoon all,

    We moved into new house (around 25 years old) recently. It's a gravity fed system (cold tank in loft, hot cylinder in airing cupboard upstairs). Pressure from all taps upstairs both hot and cold are fine. However the mixed tap in the kitchen has poor hot pressure (cold comes from the mains and is good).

    As it was a little tatty in anycase, I replaced with a new one but it hasn't cleared the problem. Although the new tap said it was suitable for low pressure, I looked into it further and the minimum pressure in the spec is 0.5bar and the research I've done suggests this is too high for low pressure?

    Do you experts think all I've done is replace one tap which isn't suitable for another, or could it be another problem?

  2. SimonG

    SimonG Trusted Plumber

    Cant beat normal taps for gravity hot water. But plenty of low pressure mixers. Look for 0.1 bar.
    • Agree Agree x 1
  3. SimonG

    SimonG Trusted Plumber

    Oh and then when you find them, open the box and make sure the flexie, prefer copper tails, are bigger than a pipe cleaner.
  4. YorkshireDave

    YorkshireDave Plumber

    You need a tap that's suitable for 0.1-0.2 bar really if its a ceramic disc type. Otherwise go for a traditional valve mechanism and that will give you much better flow.

    In terms of performance, likelihood is that you have a poor quality isolating valve which is further reducing flow. If the tank is open in the loft, then there is further likelihood that you've got detritus stuck in the pipework somewhere. The cheap iso valves narrow down to approx 8mm dia internally and that's often where it sits.

    With a low pressure system, make sure the tap you buy has copper tails as mentioned because they will impede flow by the very smallest amount.
    • Agree Agree x 1
  5. Fruitbat04

    Fruitbat04 New Member

    There is an isolating valve, which I could change to a full bore one to see if it helps. I will try a different tap and replace that at the same time.

    If there is debris in the pipe, is there any way to diagnose and if there is some, how can it be cleared?

    One thing I didn't mention is that it takes a really long time (perhaps a minute) for the hot water to get hot. I assume the cold mains is pushing it back down the pipe.

  6. YorkshireDave

    YorkshireDave Plumber

    No there is no way, that I know of, to diagnose it, it just happens very frequently with open tanks.
    Before you change the iso, take the pipe off and run the open end into a bucket. Time how long it takes opening it up fully to fill the bucket.
    Change the iso valve for a full bore version and when you've removed it run the HW gently into a bucket to see if anything is pushed through. Take care when you remove the iso valve. Sometimes you can see that the upstream side is shinier so if that's the case then it's def debris. Running the HW gently, or fully into a hose and out if poss, will generally clear any rubbish.
    Put the new iso on and see the flow rate by timing how long the bucket takes to fill again. If it's much better then its sorted. If it's around the same then the issue lies elsewhere in that same pipe but back towards the cylinder.
    That is why I'd not change the tap just yet.
    Have fun.
  7. Fruitbat04

    Fruitbat04 New Member

    Thanks very much - a few things to try there, much appreciated.
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