Boiler Continually Airing, Splashing, Overflowing - Open System, Two-Jacket Boiler Issues

Hello. I have a problem with a boiler that keeps airing, splashing, overflowing water, two-jacket boiler, open system. When I close the boiler power several times with this black valve next to the bleed valve, or the pump turns off, the air starts to escape through the vent valve, but after 2 hours in the boiler it starts overflowing again and you can hear air.

From what I read, a properly made open installation should vent itself automatically through the vessel, and for me it does not happen.

I wonder if the problem lies with the water supply to the installation. The pipe through which I admit water to the installation is led to the boiler return.

And at what height is the vessel open? Is aeration of the collecting vessel done?

The vessel is in the attic, i.e. at the highest point of the entire installation. As for the aeration of the vessel, I will not answer because I do not know, maybe the photo will answer this question. Air enters the boiler from the boiler. When I closed the valve on the pump for 5 seconds a few times, the air broke somewhere from the boiler and went to the boiler. I am surprised why the air that goes to the boiler supply and has two automatic vents on the way (you can see in the photos) does not escape through them, just stop in the jacket, and the boiler is vented when the pump stops working, or I temporarily close one of the boiler supply valves, then the air starts escaping through the vents.

And where is the check valve on the supply line to the hot utility water tank?

The very process of venting such a system is lengthy. I changed the boiler in August and there is air in the system until today. I do not care at all because many years of experience with previous exchanges shows that it will eventually die down. The fact that I use boilers with coils and it may be easier to bleed it here. But for you this advice:
Place a spirit level on the top of the boiler and check how it is fitted. If the side with vents is lower than the opposite, the airbag will still "hide" there.

Is this valve all about?

Looks like a flap check valve ...

Move the check valve over the pipe section above the domestic hot water heater between the two vents.

There is always a bubble of air or gas coming out of the boiler's power supply. The overflow vessel is probably not properly connected and there is air in the section from the boiler to the hot utility water pump. Non-return valve on off the pump is closed and here is the problem, because the way to the vent above the hot utility water is cut off. When the pump starts, you can hear the "buzzing" of water and air. The non-return valve opens. Some of the air will escape through the vent, but the rest of the small bubbles will go with the water to the hot water. And hence the "gurgling" in the hot water tank. In extreme cases, the pump may become air-bled and then it runs dry ... I do not have to describe the effects anymore.

Forget the fact that alupex is connected to the overflow vessel ... To be modernized as soon as possible.

Waldemar z Kaszub wrote:

The very process of venting such a system is lengthy. I changed the boiler in August and there is air in the system until today. I do not care at all because many years of experience with previous exchanges shows that it will eventually die down. The fact that I use boilers with coils and it may be easier to vent here. But for you this advice:
Place a spirit level on the top of the boiler and check how it is fitted. If the side with vents is lower than the opposite, the airbag will still "hide" there.

The last changes to the system were made sometime at the beginning of this year, probably February. The problem continued before and after today. From what I read, a properly made open installation should vent itself through the expansion vessel, and in my case, the air that detaches from the boiler goes straight to the boiler and, what is most puzzling, bypasses 2 automatic vents on the way.

As you can see in the first post, the first vent is mounted almost to the ceiling, and the second one is just above the power inlet to the mantle. I also checked with a spirit level and the boiler is installed correctly, by the way, I checked that they had not mistaken the power supply and installed it backwards, but everything is fine.

Added after 31 [minutes]:

Ptak3124 wrote:

Looks like a flap check valve ...

Throw the check valve over the pipe section above the hot water heater between the two vents.

There is always a bubble of air or gas coming out of the boiler's power supply. The overflow vessel is probably not connected properly and there is air in the section from the boiler to the domestic hot water pump. Non-return valve on off the pump is closed and here is the problem, because the way to the vent above the hot utility water is cut off. When the pump starts, you can hear the "buzzing" of water and air. The non-return valve opens. Some of the air will escape through the vent, but the rest of the small bubbles will go with the water to the DHW. And hence the "gurgling" in the hot water tank. In extreme cases, the pump may become air-bled and then it runs dry ... I do not have to describe the effects anymore.

Forget the fact that alupex is connected to the overflow vessel ... To be modernized as soon as possible.

You can write why the overflow vessel is badly connected and why alupex should not be used here?

The vessel is connected with PEX and probably to the riser with radiators. Re-attach the vessel directly from the boiler. The check valve can stay where it is. This galvanized tube on top of the vessel is clogged with something?

If you have vents somewhere low on the return side, close them. Try shifting the pump to the lowest gear. The pump can draw air through the vent.

The overflow vessel is not only about venting the installation, but above all for safety if the boiler boils. The most important pipe for the overflow vessel is the so-called safety pipe. There must be no valves, pumps or other devices on this pipe. The diameter of the pipe should also not be the smallest. Min ?25mm, but should be larger. A safety pipe can be a heating riser, if it meets the above-mentioned and other conditions specified by standards ...
Safety pipe should be steel or copper. It is about the high temperature resistance of the materials.

The vessel itself is also badly connected. Overflow, expansion pipe, vent ... Generally, "twists" are allowed and the safety pipe can be treated as an expansion pipe, but you need to connect it well at the vessel. Look on the forum - everything is there.

I hope that the room with the overflow vessel does not freeze in winter.

Hello gentlemen. Let me refresh the topic.
Well, I have a question, can the automatic air vent suck in air?
When only the pumps are running, the air vent that is mounted on the boiler sucked in and released air temporarily. Is it possible? I checked it on a running pump, put the bag on the vent and closed the valve for 2 seconds. When the water flow closed, the bag was drawn in and filled. I suspect these air problems in the boiler could be through the vents. There is a possibility?
I will add that when I unscrew the vent, no air flies, only water comes out after pressing the center of the vented vent.

You have a cap on the vent, so when you vent the boiler, close the vent and see if it will air.

I raise the topic because the problem is still valid, but I found out the reason why the air is still gathering in the boiler.

When I have the 3d valve set to half, on a scale of 1-6 by 3, there is no full flow of water through the boiler because half of the water returns to the system and the other half to the boiler. And the problem is the too high heating of this water in the boiler, or actually on the water grates, because the problem only occurs when burning coal and in the coking phase (I burn from the top). Both DHW and CH pumps go to the maximum, but when there is no full water flow through the boiler, it does not bring the expected effect.
There is also a second issue. Why does this water keep collecting in the boiler when I have two vents installed on the boiler and the air instead of escaping through the vent falls into the boiler shell?

Perła1985 wrote:

There is constant accumulation in the boiler, since I have two vents on the boiler installed, and instead of escaping through the vent, the air flows into the boiler jacket?

At least initially, the air will always fall into the boiler because it is forced by a quick "push" by the pump. Provided the first vent is properly installed, the second (the one above the boiler) should also "stand" on a piece of pipe that catches the flowing air. The deaeration of the boiler itself (based on my experience) takes a long time. You should bleed faster when the pump is working in the lowest gear. If you do not have fire in the boiler all the time, turn it on also in the non-smoking phase (1).

Deaeration of the boiler is not a problem here, because I vent it almost all the time by closing and opening the valve above the boiler several times. When I close the valve for 2 seconds, the air escapes through the vent and after a few closings, all the air is removed, but the problem is that when I have the 3d valve set to half, the water in the boiler gently heats up on the water grates and air is produced somewhere there collects in the boiler because there is no full flow of water through the boiler, because half of the water from the system returns to the system, and the other half to the boiler, but cannot push this air out. Only when valve 3d is closed and there is full water flow through the boiler, the water does not heat up and there is no air then.