ᐅ Air in cold water pipe: Loud noises despite normal water pressure?
Created on: 9 Dec 2025 12:02
H
holp4444
Hello everyone,
For several weeks now, we have been experiencing air in the cold water pipe, which causes loud noises when water is running (for example, when the flush tank fills, the washing machine draws water, or when washing hands). You can also notice the water turning briefly cloudy at the faucet, indicating air in the system.
We live on the upper floors (1st and 2nd floor) of a two-family house built in 2004.
When I stand in the basement near the supply line or close to the expansion tank (refix DD 12) while water is running, I can clearly hear the noises.
Since I could not find any leaks or dripping pipes and the pressure seems fine (around 5.5 bar), I wanted to ask here if you can suggest possible causes?
I just pressed the valve on the expansion tank again, and only air came out...
I have attached a few photos. Could it be that air is entering the system through a defective component in the pipe run?
I hope enough is visible despite the poor lighting conditions.
For several weeks now, we have been experiencing air in the cold water pipe, which causes loud noises when water is running (for example, when the flush tank fills, the washing machine draws water, or when washing hands). You can also notice the water turning briefly cloudy at the faucet, indicating air in the system.
We live on the upper floors (1st and 2nd floor) of a two-family house built in 2004.
When I stand in the basement near the supply line or close to the expansion tank (refix DD 12) while water is running, I can clearly hear the noises.
Since I could not find any leaks or dripping pipes and the pressure seems fine (around 5.5 bar), I wanted to ask here if you can suggest possible causes?
I just pressed the valve on the expansion tank again, and only air came out...
I have attached a few photos. Could it be that air is entering the system through a defective component in the pipe run?
I hope enough is visible despite the poor lighting conditions.
C
chand198623 Dec 2025 07:44We had similar issues with the heating water circuit. Replacing the entire expansion tank solved the problem.
The white expansion vessel has reached the end of its lifespan and needs to be replaced. The new vessel should be the same size as the previous one, at least 10% of the volume of the hot water storage tank.
Unfortunately, these components tend to have a rather short service life.
The connection nozzle should also be mounted on a special T-piece, a so-called flow divider, to prevent stagnant water. Keyword: Legionella.
Unfortunately, these components tend to have a rather short service life.
The connection nozzle should also be mounted on a special T-piece, a so-called flow divider, to prevent stagnant water. Keyword: Legionella.
C
chand198623 Dec 2025 13:23holp4444 schrieb:
How do you determine that?Simply because we solved a very similar problem this way. The air that had entered didn’t show up at the valves but was trapped in one spot in the system as a bubble.holp4444 schrieb:
How do you determine that?
Without further explanation, I don’t see any connection between my troubleshooting and the suggestion to replace the vessel. The vessel is filled with nitrogen; if the membrane has a hole, the contents escape into the drinking water system.
It’s as simple as that.
I have been dealing with this issue for two months now. We live in a two-family house with a total of six people.
Shouldn't the vessel be empty by now?
Why do I have a few days of no problems after briefly opening the safety valve once?
From my perspective, this does not make technical sense, or I am missing the logical conclusion.
Shouldn't the vessel be empty by now?
Why do I have a few days of no problems after briefly opening the safety valve once?
From my perspective, this does not make technical sense, or I am missing the logical conclusion.