Falling Pressure in Combi Boiler: 0.1 Bar Drop Daily, Leak Detection, and Tightness Check

I have a condensing combi boiler that started 4 days ago. However, I noticed that my system pressure dropped by 0.1 bar day by day. From 1.7 to now 1.4. I do not heat much for 3-4 hours a day. However, the decrease was noticeable after a dozen or so hours of break in heating, when I turned on the stove again.
Does this mean that the installation needs to be done anew? That it's leaky? This is how it looks to me, but is it possible to check the tightness of the installation otherwise than in practice to observe how the pressure drops in it?

Hello. You must control the pressure under similar temperature conditions, e.g. after cooling down, before turning the heating on again.
Is that a big pressure drop? Depends on the size of the heating system. After identifying any losses, it is worth checking all connections before turning on the heating. I had minimal cavities. There was no visible moisture in the working system. After a break in heating (3 days) water tears appeared at one radiator. After tightening (pexy) the cavities stopped.

joda08 wrote:

Hello. You must control the pressure under similar temperature conditions, e.g. after cooling down, before turning the heating on again.
Is that a big pressure drop? Depends on the size of the heating system. After identifying any losses, it is worth checking all connections before turning on the heating. I had minimal cavities. There was no visible moisture in the working system. After a break in heating (3 days) water tears appeared at one radiator. After tightening (pexy) the cavities stopped.

The pressure drop is unmistakable. The problem is that the wires are hidden in the wall and under the floor, so if something goes underground somewhere, there's no way to find it. On the other hand, I get tens of meters of underfloor heating, which is also unavailable. On the third, I'm a bit broken, because how to look for a leak?

Kurtka na wacia wrote:

bobo6969 wrote:

On the third, I'm a bit broken, because how to look for a leak?

Were pressure tests done before hiding the pipes?

Ba. Theoretically they were. I have guarantees from installers. But did they do heating or just water? I think on both. It's just that there were small corrections and then rehearsals. I do not know.
But I understand that such an attempt can be made and now. Only under what pressure is it done. Because if it is similar to what is now installed, it is probably a bit weak, because a drop of 0.1 bar is noticeable only after one day.

During heating, water may evaporate. Check (if you have not done so) with tissue or white toilet paper the connection points. Fittings should not be in the walls.

You don't have an automatic air vent there?
A freshly filled system will vent slowly for a while.

willyvmm wrote:

A freshly filled system will vent slowly for a while.

I will agree slowly but 0.1 bar a day, i.e. 0.3 bar in 3 days, is not normal for me.

I suggest cutting off the central heating installation from the boiler (if you have service / shut-off valves at the boiler) and see if the pressure on the boiler will also drop. So far, the heating season has not fully started, so you can make such attempts.

If you have a divider then you can then test with individual circuits to narrow down the potential leak location.
Make sure the installation is 100% vented.

joda08 wrote:

During heating, water may evaporate. Check (if you have not done so) with tissue or white toilet paper the connection points. Fittings should not be in the walls.

How should it not be in the walls? Everything is in the walls and under the floor, a total of 4 hmmm (tees?) For the radiators so it is impossible to check it. Nothing leaks near the radiators and the stove.

Added after 4 [minutes]:

willyvmm wrote:

You don't have an automatic air vent there?
A freshly filled system will vent slowly for a while.

I have an automatic deaerator. But it's been about a week since the installation is up and running and the bloody pressure keeps dropping. And yet when I finish them, as far as I know, the air enters again. It's a bit strange, because I haven't heard anyone screwing up the installation so that it was leaking in the walls. I have seen pex floor heating many times at construction sites. Tens of meters of pipes hidden under the floor. If it were so defective, then the floor would have to be torn off. Really the plumbers could tighten the tees incorrectly, i.e. those divergences to the radiators?

Added after 4 [minutes]:

BUCKS wrote:

willyvmm wrote:

A freshly filled system will vent slowly for a while.

I will agree slowly but 0.1 bar a day, i.e. 0.3 bar in 3 days, is not normal for me.

I suggest cutting off the central heating installation from the boiler (if you have service / shut-off valves at the boiler) and see if the pressure on the boiler will also drop. So far, the heating season has not fully started, so you can make such attempts.

If you have a divider then you can then test with individual circuits to narrow down the potential leak location.
Make sure the installation is 100% vented.

Well, but I will rather not do such things because I will lose my warranty. When I cut off the installation from the boiler, how do I check if the pressure in the boiler is constant. Well, what if it turns out that the radiator circuit is not tight? Forging all pipes?
And if it turns out that the furnace is leaky, how, where? I can see that it is not leaking.

bobo6969 wrote:

Well, but I will rather not do such things because I will lose my warranty

If you have a guarantee, chase the contractor. They can handle trials on individual parts of the installation.

bobo6969 wrote:

Well, but I will rather not do such things because I will lose my warranty.

I don't know what you are writing about. What warranty loss, from what, from closing service / shut-off valves? After all, it is normal that in an emergency you have the option to cut off the boiler from the entire central heating installation and this does not affect the warranty. Similarly, in an emergency, you can, and even have to, cut off the gas supply by closing the gas valve in front of the receiving devices, and this will not affect the warranty either. Valves are not a parade, but only closing and opening if there is a need for a moment.

bobo6969 wrote:

When I cut off the installation from the boiler, how do I check if the pressure in the boiler is constant

Well, I guess you have a pressure gauge on the boiler and you use it to check how much pressure has dropped you and hence this thread, so I still don't know what you mean.

bobo6969 wrote:

Well, what if it turns out that the radiator circuit is not tight? Forging all pipes?

You've noticed a problem and need to be resolved. First you need to find out what the problem is and then fix it. In the worst case, you may have to hammer the potentially leaky walls.
You act weird because you post in the forum but it looks like you don't want to do anything, and it is best if you want to do it yourself.

bobo6969 wrote:

And if it turns out that the furnace is leaky, how, where?

I wrote in an earlier post how to check if the pressure drop is on the boiler side. If you call the boiler service on the side of the boiler (although this is the least likely option), and if it is OK on the boiler side, there is a loss on the installation side.
You can then test on individual circuits to narrow down the area of pressure loss.

However, I see that you totally do not understand these matters, so I do not know what is better in your case, an attempt to determine the cause on your own, or calling a "specialist", the author of this "leaky" work. Since this specialist allowed such a "rub" for use, I have doubts whether he will be able to reliably fix it for you, without doing a demolition in the cottage.
Only even if you decide on your own in which circuit the defect is, the removal of the leak will still require a visit by a specialist, and because of the warranty, it is best that it was the one who did the damage, because everyone else will delete you as for a post-warranty repair.
Either way, the problem is yours and you need to solve it now, otherwise it will end up where you have cavities but then it can mean a lot of costs and additional problems.