I moved to an apartment in Luxembourg (which uses german-style plumbing) with a vented tap kitchen sink.
The issue I'm having is that when I close the tap after using the cold water, for a few seconds there will be scalding hot water coming.
This is becoming annoying and I thought of replacing the whole tap with a new one (same brand, same model).
However now I am starting to wonder if the issue might come from the water heater under the sink. We also have minor issues with water pressure in the kitchen - it takes a few seconds to build up even with cold water.

This is the first time I have a vented tap, I've always been used to classic hot/cold water coming from the main boiler, so I'm a bit lost.
These are the mounting instructions from the DIY shop https://youtu.be/7a3pr_HK76o?t=111

Any ideas?

  • Welcome to Home Improvement! It would be very helpful if you would edit your post to include the brand & model of both the faucet and the water heater. Once you've done that, take a couple of minutes to take the tour to see how this Question & Answer forum is different from general discussion boards and to learn what to expect here.
    – FreeMan
    Nov 27, 2020 at 13:55
  • Additionally, a picture of the under-sink plumbing may be very helpful. There may be something odd in the plumbing causing this.
    – FreeMan
    Nov 27, 2020 at 14:51

1 Answer 1


a vented tap system controls the flow of cold water into the heater and allows the hot water to flow freely out of it.

the only cause for hot water to come out is cold water going in.

check the heater theromstat is set correctly, and working. If it is boiling dry it could be sucking in cold water and and then blowing it back out hot with steam pressure

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