Recurring High Pressure in Nike Pilot Boiler Despite New Valve and Vessel

Hello everyone,

I have such a problem with the Nike Pilot boiler. The boiler is 10 years old and it has started to rain a bit recently. First there was a problem with turning the boiler on and the pilot flame - replacing the thermocouple solved the problem. Then one of the pipes supplying water to the boiler started to leak - replacing it with a new one solved the problem.

Now there is a fault with increasing pressure, which is indicated on the boiler, when I turn on the heating and the boiler works. At 3 bar, water began to drip from the safety valve. A service technician came and replaced the valve, plus he pumped air into the expansion vessel. After two days, the pressure rose to 3 bar again and the water began to drip. The service technician is of the opinion that this time the replacement of the entire compensation vessel will eliminate the defect. The problem is that I would not like to pack my cash in this 10-year-old stove, because in a year it may turn out that a pump will go in it and it will be another expense that will give me half the value of the new boiler after adding up to the previous ones.

Before I decide on the above-mentioned repair or replacement of the stove, new, I would like to know if it is possible to drain some water from the system from time to time using the drain cock on the boiler so that the pressure is released and water stops dripping from the valve. I am aware that this is a temporary solution, the question is is it acceptable? I would ask for help.

Hello!
Install an additional vessel and, after the trouble, blind it. The usual one should be cheaper.

Hello.
I had a similar problem with the pressure build-up in the Vaillant stove - reported in this forum. The service technician insisted on replacing the expansion vessel. However, I was not convinced of his diagnosis, if only because, after unscrewing the valve, not a drop of water flowed out of the vessel - which would indicate a damaged diaphragm. After analyzing all the possibilities, I came to the conclusion that the reason may be the valve that allows water from the network to enter the stove. The plumber put two valves (on the hose) in place of the old one and the problem is gone.
Another appeared - after reaching the set temperature, the stove does not turn off, although the controller shows that the stove is not working?
I think my hint will be useful.

Thanks for the useful info, colleagues.

However, I would still like to know if, before installing additional vessel or valves, can I release some water from the furnace through the drain cock to reduce the pressure to 1-1.5 bar, and if necessary, can I repeat this action without damage to the entire heating system?

greetings

Hello!
You have to save yourself, I think you can.

Therefore, I believe that water replenishment to the installation should not be done "permanently"
replace the release valve, drain the water to 1.5 and watch
or maybe you have a 2-function cauldron?

Yes, the cauldron is dual-function.

Although I drain the water and the pressure drops to 1.5, after some time with the heating on, the pressure starts to slowly increase again - by about 0.5, for a period of about 8 hours.

I also noticed that when the heating is turned on (winter switch) and I release hot water in the taps, the pressure on the stove decreases slightly, i.e. the pressure gauge pointer goes back by some 0.2. After turning off the hot water in the tap, the pressure returns to the state it was before opening it.

greetings

On the cold stove, set the pressure to about 85 ÷ 90 kPa. After heating, the pressure will increase to no more than 120 kPa, then equalize the pressure in the expansion vessel (it may be air, it does not have to be nitrogen) and it should be done.
I am writing this on the basis of my MORA 673 oven, also an old man, maybe 15 years old and still functional.

2 options:
1.the valve allowing water to the boiler does not hold
2 hole in the boiler water / DHW exchanger and water from the water supply is seeping in
If failure 2 is rather a new boiler
if failure 1 is not so bad

Hello.
I just fixed the problem with the rising pressure in the Thematek combi boiler. The cause was 12 cm. a pipe connecting the water pump with the expansion vessel. Pumping air into the vessel beforehand did not help, venting did not help, and neither did the release of water. The hose was clogged. After cleaning, I pumped air into the vessel to 0.6 bar, flooded and vented the boiler. now the pressure in the system is as i set 1.8 bar. Maybe my example will help. Greetings.

Hello everyone and refresh the thread,

in the case I have described, cleaning the valve that allows water to the boiler did not help. Replacing the expansion vessel did not solve the problem either. The pressure continues to increase when the heating is on, besides, it also increases slightly when hot water is released in the taps, it reaches 3 bar and ... water no longer drips from the safety valve.

Could anyone comment on this?

Well, gentlemen, no one will say? Maybe some Immergas service technician?

Let me say this, the pressure on the cold boiler should be in the range of 1.0-1.5 bar. However, the phenomenon you are talking about is a symptom of the lack of an airbag in the tank. The service technician did the right thing to inflate air into the tank and should eliminate any pressure surges in 100%. However, if the phenomenon repeated itself, it was necessary to check the tightness of the valve and not to replace the tank. And one more thing to the tank, we pump air with a car compressor after releasing water from it - press. 1.0-1.2 bar. That's all - it has to work.

In my opinion, colleague A-mail is right. If there is no valve that allows water to the central heating system, there is a hole in the exchanger for heating hot water. If the cause was in any way (broken diaphragm or lack of air) the diaphragm vessel, the pressure will only increase once more than 3 bar, the safety valve will release it, and it should not exceed 3 bar any more. If the pressure rises systematically (without admitting), the reason is the pressure (water) from the water supply to the central heating system. goes to the central heating system If you do not allow water to the central heating system and the pressure is systematically increasing, then one of these two reasons is on the bank. The valve is not so expensive, while the exchanger costs several hundreds - depending on the manufacturer and type of boiler. You can periodically depressurize the system, e.g. through a drain valve, but this is a temporary solution. Eventually you won't have time to drop this water and you'll be pouring out of the safety valve.

I have a similar problem with the MORA Z24CE dual-function gas boiler

At the beginning, one of the four gaskets that seal the heat exchanger with the water unit was damaged.
As is known, the heat exchanger consists of two chambers.
1 compartment is CCW - central hot water
The 2nd chamber is CO - central heating
After replacing the gasket, it turned out that the diaphragm vessel (expansion tank) on the gas side - "valve" is empty. According to the service instructions, the pressure in the expansion tank was pressed above 0.5 bar of the expected pressure. Then the CO system was filled with water to a pressure of 1.3 bar. Remember that the correct pressure in the gas system of the diaphragm vessel - in relation to the water volume in the CO system, takes place when the pressure gauge is connected to the CO system and the manometer supplying pressure to the expansion tank, the pressure on both pressure gauges will drop at the same time. This is done by gently bleeding air in the gas system of the expansion vessel. This operation sometimes requires repeating, so that we can catch the moment of pressure drop on both manometers. (Filling the expansion tank with air when there is water in the CO system is practically pointless). Remember this.
It is worth mentioning that the expansion vessel should be filled with argon due to the properties of this gas. However, atmospheric air hardly changes the cold water / hot water diaphragm deviation characteristics.
So you don't have to overpay for argon
As it turned out, after several hours (despite the deaeration of the central heating system - an automatic air vent in the pump housing), the pressure on the pressure gauge began to increase. After exceeding 2.5 bar, the safety valve was activated, which protects the further increase in pressure in the CW system.
This can be dealt with for a short time by bleeding the CO water down to 1 bar. However, it should be remembered that this leads to limescale, staining, and eventually damage to the gas boiler, as well as lowering the efficiency of all radiators in our apartment.
As it turned out, the repeated increase in pressure was a damage to the CO / CCW exchanger. Leakage between both chambers, which led to the ingress of tap water into the CO system. Unfortunately, the cost of the exchanger is several hundred zlotys.
Greetings.

Hello
I have a similar problem with too high pressure in the installation, I have read all the threads in this topic, similar, but I do not know how to exactly work in my stove fault. The Vaillant VU 180 dual-function stove from 2000 heats the house. The water will leak out once and the pressure drops to about 1.5 - 2 bar, the stove heats up normally, the pressure on the clock remains within these limits. When the stove and the water cool down to zero, the pressure becomes about 0.8 - 09 bar, which is too little and does not rise higher by itself, After admitting the water to the standard, according to the instructions, 1.2 bar (on a cold system), during heating, the pressure rises to 3 bar again and throws the water out through the safety valve and becomes again 1.5-2 bar. What should I do, whether the stove can work like this for some time. In severe frosts, I would not like to start anything, because it can cause even worse meatball. In addition, in the autumn, the stove without heating, which let water into the radiators while heating domestic hot water, the radiator got warm, too It calmed down for a while and it was a one-time episode. Probably a valve has blown. The stove is 12 years old and if these current water leaks are not related to this episode of heating the radiators in autumn. The service repair will be unprofitable. The stove has not worked for these 12 years with full load 24 hours a day, because there is also a fireplace. 2 years ago, someone helped me with a leak of water from the vent in this stove and I managed, everything is fine. Maybe someone will help now

Mr. Andrzej, yes, the boiler can work in such a regime for some time. However, it should be remembered that in the spring it is necessary to repair the boiler.
Continuous admission of tap water to the Central Heating system will eventually cause limescale to the entire water system, leading to a reduction in heat exchange.



What activities should you do at the moment:

1. Check that there is gas (air) on the gas side of the Expansion Vessel - (Expansion Vessel).
For this purpose, locate the location of the expansion vessel in a given boiler model.
Then find the valve on it - (the same as in the inner tubes of car wheels). Remove the cap from the valve.
2. Connect to it with a manometer (pressure gauge).
3. Check the pressure gauge - (pressure should be approx. 1.3-2 bar (with cold water in the boiler).
If the pressure on the gas side of our expansion vessel is less than
1 bar, or it is close to zero pressure.

These operations can be performed without draining the boiler water. Because we wanted to find out if there was any gas in the vessel. If it is absent or its pressure is too low -

we do the following:

1. Close the supply valve and the Central Heating return valve - (input and output).
2. Close the cold domestic water valve - (tap water) and the domestic hot water valve - (input and output).
3. Close the gas supply valve to the boiler.
4. Remove the plug from the socket (cut off the power supply to the boiler).
5. Open the boiler water drain valve.
We completely drain the water from the boiler. At the end, we also open the valve refilling water to the boiler. The flaw will drop to zero on the pressure gauge mounted on our boiler. This means that the water pressure in our boiler has equalized to the atmospheric pressure and amounts to 0 bar.
Then connect a pump with a pressure gauge to the valve of the Expansion Vessel and fill the gas part of the Expansion Vessel to a pressure of 1.3 - 2 bar (depending on the boiler model, its purpose, and the water volume that the boiler heats).
After reaching the given pressure, disconnect the pump from the valve. We check its tightness, if the valve does not let through ... Then we put a cap on the valve (plug).

We perform the next steps as follows:

1. Close the boiler water drain valve.
2. Close the valve that replenishes water to the boiler.
3. We open the domestic cold water valve - (tap water)
4. Gently open the valve that allows water to the boiler, so that the pressure on the boiler pressure gauge rises between 1.2 - 1.5 bar. After reaching this pressure, we close the valve that allows water to the boiler.
5. We open the domestic hot water valve.
6. We open the gas valve.
7. Connect the electric cord plug to the socket.
8. Start the boiler - open the tap in the hot water position. We close the tap.
Next:

1. We open the Central Heating supply and return valves.
2. Central heating is started - the water pump will be turned on.
3. Gently unscrew the air vent on the water pump (it is located at the rear of the pump, a screw is visible parallel to its shaft). Unscrew it gently with a screwdriver. There is an automatic air vent on the front of the pump. We do not regulate this vent!
4.If the pressure on the boiler pressure gauge drops slightly, gently open the valve allowing water to the boiler so that the pointer is within the pressure range described above, ie 1.2-1.5 bar.
5. The water temperature in the Central heating should be set at 80 - 90 degrees Celsius
Note that an increase in the temperature of the liquid (water) will increase the volume of the liquid, which will result in an increase in pressure. Therefore, depending on the water temperature in the Central Heating system, the needle of the pressure gauge in our boiler will go up or down. When the boiler is at standstill - (water in the boiler is cold), the pressure should always remain within the previously set limits, that is: 1.2-1.5 bar.
It is also worth paying attention to whether there are air bubbles in our radiators.
To do this, they must be vented by starting venting from the farthest radiator. The action can be repeated again.
Each venting of the radiator may result in a pressure drop in our pressure gauge installed in the boiler, therefore, each time the radiators are vented, water should be topped up in the system by adding water through the water refilling valve.

Correctly set gas (air) pressure in the Expansion Vessel is only when the pointer of the pressure gauge installed on the boiler will slightly increase when the temperature in the water system of the boiler increases. Assuming that the pressure on the pressure gauge of the boiler, with cold water, is 1.2 bar, the needle of the pressure gauge of this boiler, which shows the pressure in the water system of the Central Heating, should rise slightly.
And so with cold water - 1.2 bar, with hot water, about 60 degrees C - 1.4 bar
Then we can say with certainty that the diaphragm vessel is doing its job properly.

If the Safety Valve continues to open, please let me know.
Greetings.

Thanks for the tips and help. I decided to solve it in such a way that if, after checking the diaphragm vessel, it turns out that there is only a shortage of air and you need to finish it thanks to the descriptions on the forum, it is quite simple and I can handle it. If the vessel is to be replaced, the repair is not worth it. dishes about 500 + service, and the stove is 12 years old. I am waiting for the frosts to pass and then I will check. I am already doing some research on the new stove. For now, I do not allow water into the system, because during heating after a single discharge of water through the safety valve. , on a cold system, the pressure on the clock is normalized within the range of 0.8 - 0.9 bar and for several hours on a cold system, it remains at this level, i.e. there is no leakage from the valves of the water supply system. it is too low pressure, but temporarily I can not help it. When the stove heats up to approx. 70 c, the pressure rises to about 1.5-2 bar and no more water is expelled through the safety valve. Besides, the furnace works fine. Most likely, the fault is on the side of the expansion vessel, which does not take into account the differences in water expansion in the system. If nothing else breaks down, it will probably last until spring. I think that the topic can be finished. The help was very useful.

I will say this:
You can buy an expansion vessel quite cheaply, for as little as PLN 70. After all, it does not have to be the same shape - (they can be placed next to the boiler). When buying, it is necessary to pay attention to the fact that the new expansion vessel has the same or slightly higher pressure parameters as the original vessel had. They can be connected in place of the old expansion vessel by means of a pressure hose and two bands - metal strippers at its ends.
Mr. Andrzej, a combi-boiler can still be used for 2 or 3 years.
It happens that the rubber membrane in the vessel is damaged. A common cause is a valve in the gas part, it just lets it pass.
Therefore, at the beginning, I suggested that you check the pressure in the diaphragm vessel.
You can do it even now. All you need to do is remove the cap, the cap from the valve and press the valve pin for a short moment with a small screwdriver. When the Lord hears air coming out of the vessel, it means that there is some pressure in the gas part of the vessel. And the cause of the breakdown may be of a different type.
And yes:
1. Expansion vessel - unfortunately! Therefore, it is necessary to connect a manometer to make sure 100% that the gas part of the vessel has the correct pressure.
2. The plate heat exchanger has holes in it.
3. The three-way valve does not function properly.
4. The valve that allows water to the boiler, despite being closed, still leaks.

If I could advise you on choosing a new boiler, please take an interest in new generation boilers - condensing gas boilers.
They guarantee great fuel economy, which is the ever more expensive gas.
In addition, these boilers are quite long-lasting due to the fact that they achieve high efficiency even at low set temperatures - 55-60 degrees C. Thus, the consumption of parts, such as e.g. gas burners, is practically negligible.
If you want to "fight" with this cauldron, I can advise you.
Greetings.

Thank you for spending so much time in my case. Such disinterested courtesy does not happen every day. Tomorrow, in the morning, I will get to this furnace. I have already printed the description of activities. in any industrial technique, now I have the knowledge I can manage it. The stove has not worked too hard for these 12 years, because there is a fireplace and it does not look burned out. Once in the fall, the three-way valve passed the water from the heating of the hot utility water tank to the radiators, but it was a one-off episode. The subject of the condensing stove is new to me in terms of installation. However, I have to recognize it, because you must have an emergency exit sometimes very fast.
Tomorrow I will write whether the defect has been repaired. I will fight with this matter. If the diaphragm is damaged, I will see where and how to connect a new replacement vessel. The pressure on the safety valve. is set to 3 bars because this is the maximum pressure of the installation according to the instructions of the stove. According to the instructions for the stove, the DTR of the stove writes as follows: initial pressure 0.75 bar, capacity 8 l. So if you had to buy a replacement vessel, I do not know for what pressure.

greetings

Please kindly:
Some manufacturers specify the initial pressure (from which minimum pressure the diaphragm begins to deform) and the capacity in liters, while others specify the maximum working pressure of the vessel and the capacity in liters.
In your case, it's 8 liters.
Here is the link where you can order a similar Expansion Vessel.

http: // allegro ...

From what I noticed, the dishes I indicated were stored for quite a long time. You can take the risk and order even two pieces at this price, hangers are free . Please call them and find out what the pre-pressure is (should be similar, i.e. 0.6 - 0.8 bar) and the maximum working pressure of the vessel (should be 3-5 bar)

You should also buy a pressure hose up to 3 bar, about 2-3 meters long, and two small metal bands, screwed together with an 8 key or a screwdriver (at any automotive store).


I will answer any doubts you may have tomorrow, around 9 p.m.
Have a nice day.

Moderated By mirrzo:

I deleted the link to the auction

Aquarelle2011 wrote:

1. Check that there is air on the gas side of the expansion vessel - (expansion vessel).
For this purpose, locate the location of the expansion vessel in a given boiler model.
Then find the valve on it - (the same as in the inner tubes of car wheels). Remove the cap from the valve.
2. Connect a pump with a pressure gauge to it.
3. Check the pressure gauge - (pressure should be approximately 2 bar.

If the pressure on the gas side of our expansion vessel is less than
1 bar, ...
Then connect the pump with a pressure gauge to the valve of the Expansion Vessel and fill the gas part of the Expansion Vessel to a pressure of 2 - 2.5 bar. (taking into account the Safety Valve, which opens when the pressure exceeds 3 bar. Depending on, when in a given boiler model, for example, a Safety Valve is installed, which opens when the pressure exceeds 2.5 bar, the pressure in the gas part of the Expansion Vessel should range from 1.5 - 2 bar. bara).

You wrote some fairy tales, which I am hereby correcting:
1. The pressure is checked only after draining the water from the boiler; with water there will be no indications.
2. We pump to the pressure for a given installation; as a rule, it is 1-1.2 bar. With the pressure as you wrote, the vessel will not work, but the entire installation will work.
3. DO NOT give wrong hints

Hello, Mr. moderator.
Yes, you are right.
1. The pressure in the gas part of the expansion vessel should be checked after draining the water from the boiler (only from the boiler).
Otherwise, the pressure reading will be incorrect.
But we want to check if there is any gas in the Expansion Vessel, and this can be checked without draining the water from the boiler
In this particular case, in order to help Mr. Andrzej, you can check the pressure without major complications.
We want to diagnose whether there is any pressure in the gas part of the Diaphragm Vessel or if there is no pressure (it is close to zero)
Assuming the water in the boiler is cold, the pressure should be around 2 bar.
An increase in water temperature in the boiler will increase the pressure in the gas part of the Expansion Vessel (according to the laws of physics).

2. You wrote that we pump the gas part of the Vessel in relation to the capacity of the entire installation - naturally. So we drain the water from the boiler and the water from the radiators so as to equalize the pressure in the entire water system with the atmospheric pressure. Please do this now when the outside temperature is minus 15 degrees C. However, I cannot agree that this pressure can be 1 bar.
It should be higher than 1 bar. Please note that Mr. Andrzej mentions that the boiler heats a single-family house. We remember about static pressure, so the minimum pressure in the water system should be at least 1.1 bar. This pressure ensures the flow and proper operation of the Water Pump. Logically speaking, since the minimum pressure in the boiler water system cannot be lower than 1.1 bar, the pressure in the gas part of the Expansion Vessel should always be higher. In this particular situation, the correct pressure is 1.3 - 2 bar. This pressure was slightly inflated in the above-mentioned elaborate. The imagination and the total water volume in the central heating system in a large single-family house worked. Within this range, the Dish will function properly. Pay attention to the label on the cover of the Expansion Vessel. You need to read from it what is the minimum initial pressure. In this specific case it must not be higher than 1.5 bar.
I find no mistakes in the remaining parts of my elaborations.

Dear Mr. Moderator, it is worth adding corrections and that is why you are the moderator. However, I advise you to take advantage of more subtlety in the descriptions. After all, the most important goal is to encourage people to advise and help. That is the purpose of this forum, I believe.
It is very easy to discourage a person. It is worth considering your priorities.

Tomorrow I will introduce corrections to my scribbles.
Greetings.

Aquarelle2011 wrote:

Hello, Mr. moderator.
Yes, you are right.

I wrote here as a hint. I act as a moderator in other cases. And because I was right, I know that.
Find a way to calculate the pressure in the diaphragm vessel. Then we click, because for now only "if you"

Aquarelle2011 wrote:

It is worth considering your priorities.

The priority is to give the correct hint.

Aquarelle2011
You are wrong. The laws of physics cannot be talked about.
You only treat the expansion vessel as a "fuse" for pressure build-up at higher temperatures.
And the vessel has a few other tasks to fulfill.
I suggest you read a little about it.

I am giving the right answers. First of all, I want to help Mr. Andrzej.
And I am not self-righteous and I do not have an excess of EGO, dear moderator.
I don't have multiple accounts in this forum, I only have one account.
I do not delete posts that do not suit me, because mine must be on top !!!
MY TWO POSTS HAVE BEEN DELETED BUT I HAVE A SCAN OF THE PAGE THAT I GO TO SHOW TO THE ADMINISTRATOR, SURE I DON'T KNOW WHAT THE MODERUS IS HERE
Probably your insistence is due to the fact that I have spent a lot of time describing it in a way that is understandable, even to the average eater of bread.
I understand that I am taking the daily bread from the service technicians, because Mr. Andrzej will repair the gas boiler himself, and it's good that there are still such people. In a few years, we will start calling a service technician to our house to screw the bulb into the housing, because we will not be able to do anything ourselves.
Gentlemen, gentlemen, you draw the Dantesque scenery for today and for the future in the new generation.

I can assure you, Marek from Krakow (this is probably my cousin) UPS! that the expansion vessel is not a fuse. I meant more about the relationship - pressure in the vessel and the maximum pressure that will open the safety valve But these are academic or design considerations.
I will not go into philosophy, this polemic of the Properties of Expansion Vessels will be of no use to the reader
Bravo FOR DISCONTINUING PEOPLE WHO WANT TO HELP OTHERS !!!

Marek from Krakow, please write even better than me. Criticism itself, it's too simplistic, don't you think?
Have a nice day.

Aquarelle2011 wrote:

Marek from Krakow, please write even better than me. Criticism itself, it's too simplistic, don't you think?

Read https://www.elektroda.pl/rtvforum/topic1598401.html, only calm and willing to understand.
In short:
The pre-pressure of the expansion tank is to be lower than the pressure in the cold system at rest.
Basic reasons:
1. The tank is initially to have a reserve of water to reduce the negative pressure generated by the circulating pump. This enables the correct operation of the pump and faster "start-up" of the water circuit, also on a still cold installation.
It is like the job of a person pushing a car with another car tied behind it.
Correct operation of the expansion vessel "cuts off" the other car attached to the rear. The pump does not have to suck water from the system, it takes the "reserve" from the tank.
Of course, it must be properly installed on the suction side of the pump.
2. Failure to reduce the vacuum created by the pump may result in air being drawn in through the automatic vents, especially those closest to the pump suction side.
3. When the inlet pressure of the tank is too high, the entire system works cyclically (pressure surges) until the tank inlet pressure is reached, then the pressure increase is taken over by the vessel's diaphragm.
After a long time of such work, we have material fatigue manifested by failures in the form of cracks, leaks, etc.

At the moment I personally "remake" the effects of the expansion vessel failure.
Water is leaking through the valve and a beautiful stream. Broken diaphragm.
Twice a day I lower the pressure in the installation, releasing the air from the installation (not water, air) at the highest point (I have a valve there).
Without a working tank, air is sucked in through the vent on the stove until the pressure reaches a certain value, which causes the vent blockage.
Effect similar to a tank with too much pre-pressure that starts to run "laggingly".
Today I'm going for a new tank, I will install it next to the stove.
You have to wait for the original, installed in the oven and it costs three times more.

Something with the linking is wrong, wrong article opens.
I meant: https://www.elektroda.pl/rtvforum/download.php?id=387138
And it's not about the title of the article, you can argue with that.

First, I would like to thank my colleague Aquarele for the fact that, according to his description of the repair of the defect, I managed to remove it within 1 hour without great difficulties. You are a very competent person. This is the best description of how to remove this defect on this forum. , with many years of practice in the industry, it is obvious even for me, not from this industry, that the diagnosis should be made first, then to think about what to do next. So my colleague Aquarele directed me. By pressing the valve -vent, I found that there is no air pressure, but also no pressurized water comes out, so the diaphragm is not leaky. If I had drained the furnace water first, I wouldn't have been able to establish it.
Only then, I drained the water from the stove, replaced the valve and pumped the pressure to about 2 bar. I only have a foot pump for the wheels. In an emergency, my colleague Aquarele helped me very well. But if the moderators know better, this is what you are for, to correct and serve knowledge in order to help people in need.
In my life I have had contact with many different types of award-winning service technicians. The level of knowledge and professional integrity of some of these gentlemen was pathetic. LADIES MODERATORS DO NOT GO THIS PATH. Generally speaking, none of us is knowledgable and the forum should be used for the exchange of knowledge and assistance, but without violating human dignity. MORE RESPECT FOR PEOPLE.
After these stormy forum scuffles, now I finally do not know what, I should pump the pressure into the diaphragm vessel, because it seems that scientists' opinions are divided.
Data for my vessel according to the instructions: initial pressure 0.75 bar, volume 8 l
The water pressure in the installation, cold, is to be 1.2 bar on the stove timer
If it is possible, I am asking for specific numbers, I will set it up and that's it.
My friend Aquarele, I respect your help, please do not be discouraged and continue to help.

Mr. Andrzej, to my knowledge, the gas (air) pressure in the expansion vessel should be slightly higher than the water pressure in the closed central heating system. If you intend to press water into the boiler with a pressure of 1.2 bar, earlier (when there was no water in the boiler) you should force gas (air) into the expansion vessel with a pressure of 1.4 bar.
If your single-family house is two-story, you should assume that the pressure in the closed CO system should be 1.5 bar, so the pressure in the expansion vessel should be the same or slightly higher, i.e. 1.7 bar, etc.

Ad. Marek from Krakow.
The graduated pressure gauge, which is installed by the manufacturer on the boiler, indicates ZERO pressure, which corresponds to 1 kPa of atmospheric pressure.
Thus, when we force water into the water system of the boiler with a pressure of 1 bar (about 1KPa), there is no possibility of negative pressure, where the start-up of the Water Pump - an automatic vent installed on the same Pump, could suck atmospheric air into the water system of the boiler. This is not possible due to the pressure difference between the atmospheric air and the closed water system of the boiler.
This will not be allowed by the difference in pressure by a whole kPa higher in the water system of the boiler compared to the surroundings.

Boiler manufacturers state that the proper pressure in the boiler water system (without damaging the Water Pump operation) should be more than 1 bar.
The pump turbine is immersed in the balanced medium and the pump operation is not affected by the higher pressure in the water system.
The harmful phenomenon during the start-up of the Water Pump would arise when a significant pressure difference between the suction and discharge of water was maintained for a long time. When starting the Water Pump, the pressure on the suction side will always drop slightly. This phenomenon will not eliminate the lower gas pressure in the expansion vessel in relation to the water pressure in the boiler.
Please check the obstruction of the pressure gauge capillary installed on the boiler. Often it becomes silted with sludge, so the pressure gauge can introduce erroneous readings. And from here it is a straightforward path from loops in the problems of the Expansion Vessel, automatic vent, etc.

andrzej 3 wrote:

Data for my vessel according to the instructions: initial pressure 0.75 bar, volume 8 l
The water pressure in the installation, cold, is to be 1.2 bar on the stove timer

This is the correct data. You put 0.75 on an empty stove.
At my place (Vitodens) according to the service instructions and the name plate of the vessel, 0.75 + 0.2 bar and minimum system operating pressure 1.3 bar.

The operating pressure should be approx. 0.3 bar (minimum) higher than the pre-pressure of the vessel.
Otherwise (too high initial pressure of the expansion vessel) be prepared for noisy pump operation, system siltation, airing and mechanical failures after a long operation.

The house is two-story and the boiler is in the basement. As indicated by the foot pump from the supermarket, it is more or less 1.5-1.7. I do not have anything more precise at the moment. So far everything is OK with the installation. The stove works flawlessly. Regardless, I will be doing some research on the topic of the new condensing furnace. However, the old stove is 12 years old. I consider the topic of my defect to be finished. It went smoothly and quickly. Thank you again.
Greetings.