What is causing this knocking sound when I turn ON my hot water tap?

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musicgold

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Hello,

The video below shows the problem I am facing since I changed the mixing valve of my hot water tank. This problem occurs in the hot water tap of one of the 2 sinks in a second-floor bathroom. The problem is not occuring in any other tap of the house. The tap has two handles - hot and cold.

Symptoms: When the hot water tap is turned on for the first time, hot water flows normally. However, when the tap is turned off, and turn on again, water flows for a moment and stops with a banging sound. The flow however doesn't stop completely and a small amount of water keeps flowing.

Dignosis so far: First I thought there was an issue with the tap, so I tested the problem at the supply line level, and as shown in the video the problem remains. I also replaced the valve before the supply line, it did not help either.

video link: hot water issue
 

Jadnashua

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I can't tell for sure, but it looks like you may have flood-stop hoses. These are designed to turn off it they (think) they've detected a leak. If that's what you have, change them out for 'normal' ones, and that problem will go away.

attachment.php
 
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Fitter30

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Either has to be in the faucet or the supply pipe before the shut off valve. First water flow whatever is stopping the flow must have moved away from the stop till the water gets shut off then turning it right back on closes the stop on the second flow. Waiting few minutes faucet flows till shut off then back on.
 

Terry

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I can't tell for sure, but it looks like you may have flood-stop hoses. These are designed to turn off it they (think) they've detected a leak. If that's what you have, change them out for 'normal' ones, and that problem will go away.

I agree, it's the supply lines you're using. Get standard supply lines and problem solved.

redwood_brokenconnector.jpg


It's this part that is the problem.
 
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musicgold

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I can't tell for sure, but it looks like you may have flood-stop hoses. These are designed to turn off it they (think) they've detected a leak. If that's what you have, change them out for 'normal' ones, and that problem will go away.

attachment.php

I tried three different supply lines but the problem remains. The attached picture shows the lines I used to test the issue. All of them are from other basins in the house.
 

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