The hot kitchen tap is being a nightmare to me.

It runs OK at low flow, however as flow is increased, it starts making noise, high pitched squeal, followed by shaking and then water stops flowing altogether. This seems to be worsened as water heats up and it seizes up at smaller flows. Running the hot tap upstairs seems to make it run again. Waiting an hour or so until the water cools down also makes the water run properly.

Initially, I thought it was a worn out tap and replaced it. It seemed good at first, making some squeal noise at highest flows, but no seizing up. However after a few days, it started behaving like the old tap, so I ruled out the tap problem. The hot water upstairs and downstairs doesn't show any issues. However, I'm starting to run out of ideas what to look into, aside from replacing the whole piping in that section...

The overall hot water system is hooked up to a combi boiler.

The fixture for hot water also has a very weird setup, where it look like it was extended to make space for dishwasher.

Does anyone have any ideas what could be causing this and if it's fixable by self? And how urgent this is to address? It's using a BSP3/8 joint, which I think is acceptable for kitchen taps.

Pipes providing kitchen tap water

  • 2
    Think it might be something inside of the pipe, a blob of sediment or something. Probably just below the shut off valve. Greater flow causes it to rise up and block the valve or a small opening. Will have to turn off the water and open up the pipe. Having a bucket and turning water on might clear the pipe.
    – crip659
    Jan 14, 2023 at 19:41
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    The squealing increasing with flow makes me think of something partially blocking the flow and flapping/vibrating faster and faster with more flow. Rubber-based gaskets/washers like those in "multi turn shutoff valves" break down after years of use, faster in hot water lines. Perhaps such a washer/gasket has torn and an end is flapping in the flow, or a piece has broken off and hung up downstream in the piping.
    – Armand
    Jan 14, 2023 at 19:41
  • Sounds (squeal, and temperature-sensitivity) like a malfunctioning anti-scald (temperature-limiting) valve, but unless there's one external to the tap you've already replaced, that doesn't add up...
    – Ecnerwal
    Jan 14, 2023 at 22:19
  • 1
    Wild guess based on only the symptoms, not knowledge of the tail construction… the tails are lined with 'rubber' like a shower hose. Somewhere there's a rip in it causing high flow to make it act like a valve, flapping across the pipe diameter & sealing the flow. Running water elsewhere might just release pressure on it sufficient to let it drop back, otherwise having to wait until it's cold might just let it settle back into place.
    – Tetsujin
    Jan 15, 2023 at 9:46
  • We've got 4 answers here masquerading as comments. Any one of them would garner several up votes...
    – FreeMan
    Jan 15, 2023 at 13:46

1 Answer 1


Try clearing your line of any possible particle obstruction, to rule that out, by unscrewing the tip of the faucet where your filter screen is, place a container under the faucet so you can catch the water for examination and turn the hot water on. If there are flakes of sediment in it go around and take all of the tips off of all faucets and see how much you find.

  • There could also be crud caught at any of the valves along the way, too - the hot water knob, the shut off valve under the sink, the main hot water shut off at the heater, etc.
    – FreeMan
    Jan 20, 2023 at 13:56

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