Pressure in the water pipe increases due to water heating

Hello everyone,

we have built a new house, into which we moved in January. Since then, I have noticed the following problem:

We have a Vaillant gas heating system with solar thermal and underfloor heating.

Behind the main water pipe that goes into the house and the water meter, we have a GUBI-E water treatment device with a pressure gauge. Usually, the device shows a water pressure of about 4 bar.
It has already been noticed several times that the pressure gauge is at its limit and shows a water pressure of 10 bar. I am sending a photo with this.
The pressure in the pipe slowly builds up while hot water is being produced by the heating system. As soon as a tap is opened, you hear a backflow in the pipe and the gauge jumps back to about 4 bar.
A pressure relief valve that is supposed to trigger at 6 bar has already been replaced by the plumbing company, without success.

However, I cannot imagine that this behavior is normal and good for the longevity of the pipes.

I hope someone here among the experts can give me advice on whether this is normal, or what could be the cause.

Thank you very much!

Hi,

not good at all.... with distant acquaintances, a situation like this broke the water pipe during their vacation. The resulting water damage made the house completely uninhabitable for 6 months, all floors including screed had to be removed, etc. The damage was clearly in the six-figure range.

For them, exactly this pressure relief valve had been installed the wrong way around, so it could not trigger.

Definitely keep on it!

Best regards,

Andreas

Hi

There is no visible pressure relief valve there.
It is a filter with a pressure reducer.

The cause of the pressure increase in the cold water installation will be a faulty or contaminated safety group of the water heater.
When heating the hot water, the pressure in the tank usually rises up to 10 bar.
A functioning safety group normally prevents water from flowing back into the cold water pipe.

Olli

Hello

This part is installed on the heating system and according to the plumbing company, it is supposed to prevent overpressure. However, this part has already been replaced and the problem still persists.