[Solved] Step-by-Step Guide: Adding Water to Vaillant VC / VCW 789/0 Gas Oven

Hello,
will someone give me how to top up water to the Vaillant VC / VCW 789/0 gas oven? I see the red knob, but do not you need to unscrew a valve?

What for? After all, gas furnaces do not have a water tank (they heat through). You can refill the water in the heating system by unscrewing the valve that is usually not on the stove.

And why is it a red knob for bars and a pressure gauge on the stove?

This red is a safety valve. Check this white knob that looks like a used bottle cap.

Sarunia89 wrote:

And why is it a red knob for bars and a pressure gauge on the stove?
...

For what you wrote and not to top up the water in the oven, because as I wrote the furnaces which do not have a water tank, hence there is no such thing as water replenishment in the heating furnace

This white knob is impossible to move, at least I did not manage.
And if the counters indicate 0, does it mean something is happening? To call a professional or something I can try myself?

DiZMar wrote:

What for? After all, gas furnaces do not have a water tank (they heat through). You can refill the water in the heating system by unscrewing the valve that is usually not on the stove.

Why do you complicate a simple matter. It is known that it is usually about water filling in the central heating system, and for Kowalski, this means adding water to the boiler.
At the moment, it is just clinging to the name, because at the end the layman and the connoisseur are talking about the same thing.

Sarunia89 wrote:

I see the red knob, but do not you need to unscrew a valve?

This sentence formulates that you tried to spin the red knob but it did not work, so you are wondering what else to turn.
This red knob is called a safety valve that opens automatically if the system pressure exceeds 2.5-3.0 bar and then the system water flows out into the drain to reduce pressure.
If you tried to turn this knob, you just dropped the water from the circuit and the pressure on the boiler dropped to zero.
In such a case, one should turn the knob further in accordance with the arrow, until the characteristic shot, then the valve closes, so you have to stop spinning quickly, because turning it opens the valve and you can turn only one way.
It is worth to unscrew the hose from this valve and make sure that there is no water leakage from this valve.

Sarunia89 wrote:

And if the counters indicate 0, does it mean something is happening?

Zero bar on the pressure gauge means that there is no water in the system and there is no pressure required.
The reason for this may be, for example, a water leak from the circuit that is not visible, and even a sudden air leakage from the membrane vessel, which is usually on the back of the boiler and the air filling valve is at the top near the exhaust pipe.
You can try to check the air pressure in the vessel yourself, fill the water in the circuit and see if the pressure will be kept at the minimum level during the boiler operation, but you must have some pale idea of what you are doing.
I do not know how to top up water in your boiler, since, as you say, the potential white knob does not stir, and there is no other filling valve.
In this case, it can be difficult without a specialist, because you will damage something more quickly than you can fix.

In the boiler, there is a valve that allows water - as a colleague earlier described such a used white cap as from a bottle. Actually, it can be baked and you can not move it, you will sooner be able to break something.
On your last photo you can see a pressure gauge and before it a strange bubble, or a pressure reducer connected to a copper pipe on the return of CO to the boiler. This is a water intake to the central. Somewhere before should be a regular valve that is probably closed. Try to find and open it. If not, take more photos of this installation or call a professional.

The problem is already solved, thank you all for the answers. The main valve was located on the bottom of the bottom tube and it was only necessary to unscrew and top up the water. For the future, I am posting a picture with a marked valve, maybe someone will need it. Greetings.

Cool.

I have only one comment. The valve that you unscrewed is the cold water that is heated by the so-called boiler. CWU, but also lets water through the reducer into the CO system. This is called constant pressure regulating the constant pressure in CO. The problem may be when the safety valve (the one with the red cap) passes through the green hose, probably directly to the sewer. Then again the system is supplied with fresh water and again dropping etc. This can lead to the replacement of the boiler - its main exchanger. Check whether the safety valve does not leak water - from a green hose. It is best to take this hose to the bottle and then you can see if there are leaks from CO or not.

ls_77 wrote:

Check whether the safety valve does not leak water - from a green hose. It is best to take this hose to the bottle and then you can see if there are leaks from CO or not.

The hose has a nut, so it will be easier to unscrew it, then we will have a direct view of the valve itself, which makes it easier to see even a dripping drop from the valve.

BUCKS wrote:

Why do you complicate a simple matter. It is known that it is usually about water filling in the central heating system, and for Kowalski, this means adding water to the boiler.
At the moment, it is just clinging to the name, because at the end the layman and the connoisseur are talking about the same thing.

Technical formulas from gimbazy will soon become common.
I recommend reading
http://redinpe.com/attachments/o_slownictwie/slown_13.pdf

Brencik wrote:

Technical formulas from gimbazy will soon become common.

Do you see this subtle difference?
The amateur attaches photos and asks for help in how to top up water.
In response, he gets:

DiZMar wrote:

What for? After all, gas furnaces do not have a water tank (they heat through). You can refill the water in the heating system by unscrewing the valve that is usually not on the stove.

it is the answer that adds nothing to the thread and only causes penance in getting rid of the low level addition.
First of all, we talk about the 2-function boiler and as far as I know it is usually the water filling valve is just built into the boiler, so in my opinion DiZmar is wrong to claim that such a valve is usually outside the boiler.
Secondly, there are no gas stoves what, because they are boilers what, so DiZMar clings to pouring water to the boiler, while he uses the term "furnace", which smacks of amateurishness.

I suppose you support DiZmar, but you do not notice the mistakes he made.
I did not intend to point out these errors but your post initiated it.
This forum is for amateurs and mistakes are acceptable, and too much clinging does not change anything. If someone in the first post draws attention to some error in the wording, it's OK, but let it add something useful. Then such a post will have an editional and auxiliary dimension, and it has not served only to tickle his ego of a pseudo professional and a speculator of technical wording.
And this is what I am saying only: the pot was coming to a cauldron.

BUCKS wrote:

...
First of all, we talk about the 2-function boiler and as far as I know it is usually the water filling valve is just built into the boiler, so in my opinion DiZmar is wrong to claim that such a valve is usually outside the boiler.
...

I just have to bake or if you prefer a two-function boiler. As he called, he called. The boiler is associated rather with a container for water, but this is not the point here. The valve to refill water in the central heating system (not in the boiler, because the water in the boiler is in sufficient quantity all the time) outside the boiler but even in the next room. There is no such valve in the boiler. There was no such valve in the boiler also when I had a single-function (only what). These usually everyone has its own as you can see. I am mine and you mine.

DiZMar wrote:

I just have to bake or if you prefer a two-function boiler. As he called, he called. The boiler is associated rather with a container for water, but this is not the point here

Is it possible for a computer monitor to speak TV now?
A calculator on the cash register. In the same way you say that it's a stove.

Brencik wrote:

DiZMar wrote:

I just have to bake or if you prefer a two-function boiler. As he called, he called. The boiler is associated rather with a container for water, but this is not the point here

Is it possible for a computer monitor to speak TV now?
A calculator on the cash register. In the same way you say that it's a stove.

I do not know if you know that some computer monitors have TV functions and there are more and more of them on the market? The cash register is nothing more than a calculator with a printer extended with additional functions.

DiZMar wrote:

I just have to bake or if you prefer a two-function boiler. As he called, he called. The boiler is associated rather with a container for water, but this is not the point here

It's just that the pot was coming back to the pot.
You pay attention to Sarunia89, because she wrote about adding water in the boiler instead of in the installation, as if it was a reprehensible mistake, and at the same time you do not see the difference between the stove and the boiler.
No matter what you associate with, you made a mistake, and yet you do not have the courage to admit your mistake, as if at any price you wanted to have the feeling of being someone better

DiZMar wrote:

The valve to refill water in the central heating system (not in the boiler, because the water in the boiler is in sufficient quantity all the time) outside the boiler but even in the next room.

Do you have any idea how a gas boiler is built and where there is boiler water in the boiler, what do you say that the water in the boiler is always sufficient?

DiZMar wrote:

There is no such valve in the boiler. There was no such valve in the boiler also when I had a single-function (only what). These usually everyone has their own as you can see. I am mine and you mine.

.
How many saw 2-function gas boilers? I have at least a few and each of them had such a valve factory built into the boiler.
The term "usually" does not mean everyone, so in my opinion I used them in a reasonable way. In turn, your term "usually" based on the experience with only one 2-boiler boiler no longer fits.

To sum up, deal with "calculator with a printer", because maybe you have more knowledge and practical experience there, you will have greater power to improve other users.
For so far, the Heating Department recommended embarrassment, and I think it was supposed to be professionally.

DiZMar wrote:

I do not know if you know that some computer monitors have TV functions and there are more and more of them on the market? The cash register is nothing more than a calculator with a printer extended with additional functions.

Yeah, and every second guy with a pitchfork is Poseidon.

A stove and a boiler are two different things.
I understand that some women do not differentiate between electricity and tension, but God, let us go this way!