Saunier Duval CO Furnace (KLZ30): Expansion Vessel Pressure Setup without Draining Water

Hello,
I have a Saunier Duval CO furnace (bear KLZ30) - what pressure to set in the diaphragm vessel for CO, but without draining the water from the circuit, the pressure on the furnace is 1..1.5 bar. The valve in this vessel has blown out, whether it has to be nitrogen or is it normal air.
There were similar topics, but you would have to close the circuit to the stove and drain the water, but it is easier to set the pressure without releasing but how many to set ???
:)

Greetings
Zbyszek

kalgonmalutki wrote:

... Sometimes a check valve is installed between the expansion vessel and the installation ...

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Quote:

? You probably wanted to write a quick coupler with a foot valve.

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Sorry for the font.

The surest way of filling-pumping a diaphragm vessel, without releasing the network pressure, is to pump the vessel until pumping starts to increase the pressure in the system.
This will mean that the water contained in the diaphragm tank begins to squeeze into the central heating installation.
At the moment when squeezing the water from the diaphragm tank no longer affects the pressure in the CO system, it means that there is no more water in it, i.e. it is empty.
Then the pressure in the diaphragm tank should be reduced by approx. 0.2. atm.
And we have the same as with standard pressure filling.

The effect will be similar but not the same.
You should add that you have to bleed the water to the required pressure, otherwise it can be deduced that you are only pumping air where the 12l of water from the vessel is divided.

kalgonmalutki wrote:

The pressure value should be stated on the rating plate on the expansion vessel

Not true. The factory value is given there. Ultimately, it is adjusted to the installation conditions.

kalgonmalutki wrote:

Sometimes a check valve is installed between the expansion vessel and the installation.

Not true! It would make no sense to have such a vessel! Only foot valves dedicated to diaphragm vessels are installed.

piracik wrote:

The effect will be similar but not the same.
You should add that you have to bleed the water to the required pressure, otherwise it can be deduced that you are only pumping air where the 12l of water from the vessel is divided.

Just 12 liters of water from the vessel, while pumping air into the vessel, it begins to increase the pressure in the installation I wrote about.
By paying attention to the pressure, especially when increasing the pressure in the tank starts to affect the pressure in the system, it is possible to spill the moment when the pressure of the tank is equal to the pressure in the system.
By lowering the pressure of the tank by 0.2 atm. we introduce about 2-3 liters of circulating water into its volume, which gives the correct proportions between the volume of the cold system and the volume of the hot system.

Hello, current topic, winter is coming ...
My point was that if the stove has a pressure gauge for its central heating installation, and I have a pressure gauge connected to the expansion vessel, I can calculate how much it should be. let's assume that the water should be 1.3 bar and the membrane vessel empty by 3.3 bar less (?), i.e. at 1.3 on the stove clock, the mamometer on the valve should show 1.3 + 1 = 2.3. I know that pumping up affects the gauge on the clock, making it a bit tricky, but faster than draining the furnace itself. I do not know if the calculations are consistent, although the logic of electronics and not physics should be ok. You can insert the pressure hose from the vessel outside (there is even a factory hole in the furnace casing) and control the pressure without any problems - in Saunier Duval it is a vessel quite hidden in in the middle ... then we have a minimum of work. The stove is already 11 years old (it works flawlessly), it is time to replace the vessel, but as soon as it can be pumped up, maybe there is no need to spend PLN 200 ...
greeting Z.

You're a little nonsense, buddy kalgon, tiny ...

calgon tiny, then tell me how is your teria to the vessel, e.g. reflex type N, which has an initial pressure of 1.5 bar, and for example the pressure in the installation is maintained at 1.2 bar. It makes sense?

Have you read the manual you posted?
Read well and don't write nonsense.

Approximately 0.3 bar less than the minimum required for the installation.

This is why there is a valve in the vessel to regulate the nitrogen or air pressure, depending on what was loaded there by the service technician.

Hello, everything is fine, after filling the above description, it worked properly throughout the season, i.e. the pressure on the pressure gauge was 0.7 (cold stove) to 2.0..2.2 (stove heated to the maximum), from the drain pipe the valve did not throw anything away all season. In the future, I will make a hose to refill or measure the pressure, if necessary, without disassembling the boiler.

zbrozw wrote:

the pressure on the manometer was 0.7 (cold stove) to 2.0..2.2

I do not want to worry my friend, but it is not correct

zbrozw wrote:

Hello, everything is fine, after filling in the above description for the whole season it worked properly

Well it's not okay ...
Either, my friend, you have inflated this vessel the wrong way or it is not fully functional ... The vessel is designed to eliminate the thermal expansion of the liquid resulting from the laws of physics. So as you can see, yours is not compensating for these jumps ...

Hello,
if it was wrong, the pressure was over 3 bar and the valve was throwing out water. The stove is already 12 years old, but from what I remember, the water always increased the pressure by about 0.5-1 bar (the law of physics) when heated. Maybe I'm exaggerating with these values, but they are the extreme ones I noticed last winter. Overall, this is probably not a bad result, I do not think that such a "bubble" can stabilize the pressure in a fairly large house (and installation) rigidly. Maybe it would be worth replacing it, but why if it behaves rather correctly? Will consult at the next service ... :D

The topic was not created to annoy the service technicians, but as an idea of how to quickly set the pressure without touching the valves in the furnace at all (closing the water, draining the water in the furnace itself, etc. - the furnace is 12 years old, so are the valves ...).
Overall, I consider it a good and quick patent ...

PS I guess you will have to switch to summer mode soon ...

Such large fluctuations in pressure may indicate that the vessel is too small for the installation.

Gentlemen, full spring, we are ending the heating season and here there are disputes over the superiority of one theory over another ...
I think so, since the valve did not throw anything away and the stove also works ok, what more to look for. The pressure shown by the manometer on the stove is actually a temperature, because it only has a scale in bars and does not measure the pressure (it would be too expensive), but it has a copper wire and measures the temperature and shows the proportional pressure in bars. So, according to fellow automation engineers, the furnace can be stabilized so that it always has a constant temperature - in the morning, night work during the day - I am an electronics engineer, but I do not believe in such miracles even in the era ... Besides, I would not like to pay such bills ...
Until next season ...

zbrozw wrote:

The pressure that the pressure gauge shows on the stove is actually the temperature.

Pressure is pressure. How else would you fill the installation? By measuring the temperature?
Just because you're happy doesn't mean it's OK.
Other users are also reading this topic and we must not mislead them.
At the pressure you specified 0.7 bar and high installations, the radiators in the highest places will already have air in it.
In 90% of the boiler rooms I deal with, the pressure fluctuates between 0.2 and 0.4 bar between the pressure on the cold and the hot system.
You don't have to cheat physics here.

Added after 2 [minutes]:

zbrozw wrote:

So, according to fellow automation engineers, the furnace can be stabilized so that it always has a constant temperature - in the morning, night work - I am an electronics engineer, but I do not believe in such miracles even in the era ... Besides, I would not like to pay such bills ...

Yes. This is the effect of weather control with a large modulation of the burner.
The bills with such control are lower, so I don't know why you wouldn't want to pay them

The next time I take the cover off, I will take a photo of the pressure gauge - thermometer. In electronics and automation, everything is a matter of agreement - why install a pressure gauge for a couple of euros or a digital pressure sensor for a dozen or so, when an ordinary thermometer on a wire will do the same? It's all about the indicator ...
The weather is one thing but the thermostat with a programmer turns off the stove for the night and it cools down (not the house) for 5..7 hours. Temp. in the house it drops by 1..2 degrees but the stove is completely cold, the water is as much as the surroundings about 20C and the pressure is also (or rather its reversal on the scale of the thermometer - manometer). Accuracy can be poor because why should it be better. As I wrote, the stove itself is 12 years old, so such a pressure gauge may not show the truth, right?
He writes about the Saunier Duval CO stove (KLZ30 bear).

It is not conventional whether the pressure gauge is a thermometer and vice versa.
Pressure gauges also exist on the wire and are doing well.
Not everything has to be digital.
The fact that the boiler turns off for the whole night does not mean that during the day it will not do it with a vengeance.
I have more and more customers who have come to the conclusion from their own observations that it is cheaper to maintain a constant temperature in a room than to reduce it at night.

Place and method of installation of the MANOMETER capillary in your boiler.
It is screwed on, and the thermometers are not screwed on.

So the technical issues have probably been sufficiently developed and explained here. If a colleague still insists that "this is good" and does not want to accept that there is something "wrong" with the vessel in this case, then there is no point in further exploring this topic. As my colleague "piracik" rightly pointed out, this topic is also watched by others. We cannot discuss such discussions on the service forum, because they are harmful to others.

Hello,
ok, the topic of the manometer with a capillary arose unnecessarily, there is no point in pulling it, if it is wrong, I'm sorry ...

The subject of the post was this is it possible to set the pressure in the expansion vessel without draining the water and how much to set .
Reason e.g. valves are stony and cannot be moved and I do not want to drain all the water or I am lazy .

Can it be done in 5 minutes - YES
How many to set - none of the installers wrote back to me
I set it according to the above calculations - maybe not entirely correct, but in general, the pressure did not exceed 2 bar and the 3-bar valve did not throw anything away all winter
Is the vessel ok - probably not because, as I wrote, it is 12 years old, the valve has broken and there is air in it, not nitrogen, and probably after this time it is suitable for scrap.
Why do I not replace it (installer) - probably someday yes, but if it can be paid without costs, not now.

And this is where I end this discussion and I cordially greet those who write and read in the future ...

You can try this way.
Release the pressure in the system to a pressure lower than that required in the vessel.
Top up the air in the vessel and at the same time release the water until the required pressure in the vessel is in the vessel, and the pressure in the system is lower than that in the vessel.
The point is that there is no water in the vessel.
The pressure value in the vessel should be about 0.3 bar lower than the rest pressure in the installation.
If the installation is to be 1.5 bar, then the vessel is 1.2.

The fact that there is air does not qualify as a scrap vessel.
If the air is not escaping, the vessel is working, the water flows in and out, then it is OK.

The fact that you do not exceed 3 bar is OK. Check that the pressure in the cold system does not fall below that resulting from the height of the system. That there is air in the heaters on the upper floors.
1m of installation height equals 0.1 bar of pressure on the boiler.

Thanks to "piracik" this is what I meant ...
And how do I connect the pressure gauge to the diaphragm bulb after setting it, it will be 1.5 + 1.2 = 2.7 bar or otherwise ???

The pressure in the vessel will be equal to the system pressure.

Everything ok, pressure has been normal for over a year without draining the water from the furnace.