Title: Junkers Cerapur 2200W vs GC 2300W: Opinions, Differences, and Heating System Modernization

@ diodak_13
Could you please send me a page or document where it is accurately described and calculated how clocking and continuous operation affect energy consumption? I've been looking for such a study for a long time, but on the Internet you can only find gibberish from producers.

diodak_13 wrote:

ERROR, by no means. Regulators that communicate digitally are the best. CW400 is expensive but CR100 (weekly room) or CW100 (weather) can be inserted. The electronics calculate the burner power on an ongoing basis and adjust it to minimize the timing and optimize the operation of the entire installation.

It is known that dedicated ones work best, as you write, for example CW400, but in my opinion they make sense if the boiler allows on average continuous operation of the burner.
Therefore, do you recommend CW400 for premises, e.g. 80m2, which has a demand of 4kW for -20, i.e. on average in the season it gives 1.8kW by design, and the boiler has a minimum of 5.2kW.
Comparing it to a car, it is like driving a housing estate road, where 20 km / h is required, and the car allows you to drive at least 50 km / h.
How such a regulator is to calculate the burner power, if the boiler minimum exceeds the current demand and the demand for frosts -20.
It is impossible to avoid timing, even if the boiler was to work only at minimum power, so the sense of buying CW400 is highly debatable.

It is different if someone has a place that needs approx. 11.5 kW for frosts -20 then on average during the heating season will need 5.2 kW, then CW400 makes more sense.

diodak_13 wrote:

Secondly, it does not require battery replacement - it is powered by the boiler.

In my opinion, such an argument is funny, because if I live in my flat on a daily basis, the replacement of the battery, two AA / R6 fingers every 2 years is no discomfort, especially as with, for example, the Salus RT510RF, you do not have to remove the regulator from the wall. But if we assume that a part of society needs instructions not to put a foil bag on your head because you can suffocate yourself, then this is the most sensible and factual argument. ;)

diodak_13 wrote:

The ON-OFF regulators work like, for example, in a car the gas pedal pressed down to the stop or released, they will also work

This is a bad example.
The ON-OFF regulator gives only the signal, driving (heating), stop (heating pause), and how the gas pedal will be pressed depends on the boiler operation algorithm used by the manufacturer and on the boiler parameters settings in its MENU. In practice, usually the boiler for central heating does not have to work at maximum power, so having a boiler with a power of 24kW, we do not use this power for central heating, and if this happens, it will be for a very short time, so it can be assumed that there will almost never be such a need.

diodak_13 wrote:

Or else it is like driving a car and braking sharply at each speed limit, and accelerating sharply when there is no speed limit.

It fits sooner

diodak_13 wrote:

The digital regulator reacts in advance to all changes and, having a weather sensor, works much more efficiently and economically. It is important to put the boiler and the regulator in a good position.

and how will the CW400 regulator behave when the premises need, for example, 2.6kW, and the boiler offers a minimum of 5.2kW. No CW400 will limit the power, only the boiler will have to stop suddenly,almost the same as with the ON-OFF controller, so the advantage of CW400 over ON-OFF is questionable and highly debatable.
Much more efficient and much more economical work is a wishful thinking rather than a fact.
I agree with this statement, for a place that needs 11.5kW at sea -20 if someone wants Bosch 2200.
On the other hand, Bosch 2300 with a minimum power of 3.4 kW will meet the same condition for a premises with a demand of 7.5 kW for frost -20 and then the purchase of CW400 is worth attention.

zerthimon wrote:

Could you please send me a page or document where it is accurately described and calculated how clocking and continuous operation affect energy consumption? I've been looking for such a study for a long time, but on the Internet you can only find gibberish from producers.

there is no such study, because as you say, everything is marketing gibberish, although it makes sense.
The manufacturer states the efficiency for Bosch 2200:


I treat it as the values of laboratory conditions, because in practice, during the operation of the boiler, deposits are formed in the installation, so the efficiency deteriorates over time.
The table gives a point of reference that you can achieve certain efficiency by meeting certain conditions.
Since conditions are variable, efficiency is also variable.
Unfortunately, at home, you are not able to determine your real efficiency under certain conditions or at the current moment.
Therefore, you will not determine how much you lose by timing the boiler and no one will tell you specifically, so you will not calculate whether it is worth worrying about timing for gas consumption.

I would say yes, the most important thing is that the comfort is as satisfactory as possible, then if I can improve something, I try to change the boiler and regulator settings so that the timing is reduced. If I can't change anything else, I leave it as it is.
For me, in an uninsulated flat, in pre-war construction, the timing has an impact on my feeling of thermal comfort, so I emphasize the boiler with the lowest minimum power possible so that the burner can operate continuously from the highest possible outside temperatures.
I only have an apprenticeship in my building, so I don't know how comfortable I would feel in modern construction. In addition, everyone has their own level of comfort, so everyone will judge by their own measure.

If you have a boiler and you are satisfied with the comfort and you do not mind the potential timing, leave the topic and do not worry about it, because it does not make sense.
I emphasize that I am an advocate of buying a boiler that offers the greatest possible flexibility, because then I know that I bought a boiler with the lowest possible power and if it does not meet my expectations, then when buying a boiler with a minimum power of 5.2kW, I will not wonder what would happen if he bought boiler with a capacity of 3.4 kW.
Currently, I have a boiler with a minimum catalog power of 9.1kW for 80/60 water and I can see the consequences for me.
Assuming (because I do not know it 100% and these are only my estimates) that I computationally need 8kW for frost -20, then calculate on average +2 degrees outside, the average power demand is 3.6kW.
With such conditions, it is obvious that I see as optimal a boiler with a minimum power of 3.4kW instead of 5.2kW.

Since new buildings have less heat demand than my losses, it does automaticallythe need for a boiler with a lower minimum power, and this is what I emphasize in my statements, suggesting boilers with low power.
But a modern, insulated building also has different thermal characteristics, so an oversized boiler will have different thermal sensations than in my apartment, so it does not necessarily have to provide poor thermal comfort, because everyone feels it differently.
In other words, I do not insist that in a modern building there must be a boiler with a low minimum power, but due to the purchase for about 10 years, I prefer to buy the best possible boiler than to make a beta tester of an oversized boiler, since I had the opportunity to buy a boiler in theory better suited.

@BUCKS
Another question then. When does the boiler work at minimum power? How is the return temperature similar to the supply or how is the return temperature similar to that in the table, e.g. 50/30?

I am asking because when I have a max temperature set on the boiler to 50, it often happens that the return is not much colder than the power supply. Now I am wondering whether I should reduce the maximum temperature to, say, 45. The return will be cooler, because the apartment will take a lot of energy, but will it not stimulate the boiler to work harder? Because the difference between feeding and returning will be significant. I checked it this winter and the boiler was heating all the time, but I'm not convinced that it was at minimum power.

zerthimon wrote:

Another question then. When does the boiler work at minimum power? How is the return temperature similar to the supply or how is the return temperature similar to that in the table, e.g. 50/30?

I don't know your boiler, so I don't know 100%.
But overall the "intelligence" of the boilers is rather simple and similar.
In my atmospheric Vaillant boiler, its work cycle is repeatable:
1.start the burner with minimum power - for me it is about 9.5kW for boiler water 80/60 - this operating mode is always maintained for the first 2 minutes after the burner starts.
The 2nd boiler switches to the intermediate power set in the boiler MENU. Intermediate power is the maximum power for what I can set it in the range from 9.5-24kW.
As my boiler is twisted to approx. 17.2kW, I can set the intermediate power in the range of 9.5-17.2kW.
Since the adjustment mechanism of the gas valve is, in my opinion, not very precise, in practice I have a displacement power with the following values:
9.5-10-12-14-16-17kW.
Currently, the indirect power on the boiler is set to 12kW, which means that after 2 minutes of operation at the starting power, the boiler switches to the 12kW operation mode.
3. If the flow temperature reaches the temperature by 2 degrees lower than the preset boiler temperature, the boiler starts modulating in the range of 9.5-12kW depending on the boiler water temperature.
Due to the low precision of the control, the power pulses.
The boiler detects the temperature by 2 degrees lower, it limits the power, but the water flow gives cooler water all the time, so lowering the power causes a temporary decrease in temperature, so as a result the boiler gives more power, because the step of changing the power is quite large, the temperature is temporarily increased and the boiler lowers power again and so on over and over again.
4. When the boiler water temperature is stabilized, the boiler works stably at its minimum power until the set temperature is reached and the burner is turned off.

Your boiler will work similarly, but it has its own operating characteristics, which I do not know, so below are my suspicions of how it can work based on my knowledge and analysis of the issue on the example of my boiler.

I assume that your boiler starts at start power X and almost immediately switches to intermediate power, i.e. the maximum power for the co-mode

Your boiler in MENU has a maximum power control, but in the range of 50-82%, and not, like mine, from minimum to maximum.
On the other hand, for domestic hot water, you can set the maximum in the range of 50-100%.
We know from technical data that for 80/60 boiler water, your boiler has a maximum of 25kW for domestic hot water and 20kW for central heating.
82% of 25kW is 20.5kW, so it fits.
This means that with the value of 82%, you have 20kW set, and with the value of 50% it will be approx. 12.5kW for the co-operation mode.

In other words, I can force my old boiler to work constantly with minimum power, regardless of the heat demand, and you can no longer force settings.

Only now, to confuse you, the minimum power can be set to 10-49%.
Assuming that after setting 10%, we get the minimum power, which according to the technical data is 4.8kW for 80/60 water, then according to arithmetic, the max should be 48kW, and as we know it is 20kW for central heating and 25kW for domestic hot water.
You also have to look at these percentages with a grain of salt.

But suppose the transition to intermediate power c.about. means work with a maximum power of 12.5 kW (80/60) after setting the value of 50% in the boiler menu.
This means that the boiler in the co mode will be able to modulate the power in the range of 4.8-12.5 kW (80/60).

My boiler starts to modulate at 2 degrees below the set value, is your boiler similar, or will it decrease only when it reaches the set temperature, I don't know, you would have to check the algorithm of your boiler's operation yourself.
Of course, the boiler can modulate earlier if it detects too much temperature rise due to e.g. limited water flow, because e.g. thermostatic heads will be too closed, etc. and continuous operation at a given moment with an intermediate power of 12.5kW will not be possible.

Let's assume that the minimum power of the boiler is reached when it gets close to the set temperature.
Your boiler also has an interesting hysteresis function, which, as I understand it, means that when you reach the set temperature, from now on the boiler heats only at the minimum power, but it can overheat the water by the set hysteresis value, i.e. you set the boiler to 50 and having a hysteresis of 5 degrees, the boiler can heat water to 55 degrees, constantly heating on minimum power before turning off the burner at 55 degrees.

There is no typical hysteresis value in your boiler, but there is a temperature interval parameter ranging from -2 to -15 degrees, the factory default value is -6.
I'm not 100% sure, but I assume it works like this.
If you set the interval to -6, then after setting 50 degrees, the boiler heats up to a maximum of 56, but after turning off the burner, it will turn on heating after the temperature drops to 44 degrees. In addition, there is also the parameter of the temporary blocking of the burner, so the actual time of firing the burner may be different.

Now, an example and my guesses on how your boiler works.
Suppose you set your boiler to 50 degrees and you have a factory temperature interval of -6.
When you turn on the burner, you have 30 degrees in the installation.
The boiler starts with the starting power X.
It goes into the 12.5kW indirect power mode and heats all the time until it reaches about 50 degrees, then it modulates and goes down to a minimum power of 4.8kW and heats with this power of 4.8kW until it reaches 56 degrees, unless earlier the room regulator turns off the heating request.
If you now set the same temperature interval -6 on the boiler to 44 degrees, assuming that the boiler turns on at e.g. 30 degrees in the system.
it heats with a power of 12.5kW until it reaches about 44 degrees, then it heats with a minimum power of 4.8kW until it reaches 50 degrees. It will be turned on again after the water has dropped to at least 38 degrees.

I hope that you would like to read my elaboration carefully and that it will be useful for you and it will not be wasted.
I do not give a 100% guarantee, because I do not have this boiler to test, but for a while as an amateur I had to deal with the Junkers MIDI, Compact and Bosch 2200 and I came to such conclusions during a one-time, short contact with these boilers.
I am more of a practitioner, so I like to have the equipment in my hand to be able to play with it, but I will not buy and exchange boilers for tests, so my practical knowledge is limited, but I already have a small vision as to how I would like my boiler to work in my apartment.

Added after 8 [minutes]:

the above applies to work with the ON-OFF regulator, because CW400 controls the boiler operation and instead of working with an intermediate power of 12.5kW until reachingof the example 44 degrees, the boiler can be turned on with a lower power, as diodak_13 wrote earlier, but if the boiler is too oversized, then in my opinion such intelligent control loses its importance.

Thanks a lot for your comprehensive answer. I have read it in full, your efforts have not been wasted

Hello you I would like to thank you once again for your help in choosing a boiler. Your knowledge is invaluable. I'm buying two more of these boilers for other apartments because this one worked perfectly. I came by to thank you

Question about the Junkers GC2200.

Will it suffice to heat a house with a lower and upper level that has a combined area of about 200 square meters; and, can it supply hot water on the upper floor without the need for an extra heated water tank?

Thank you for any information and guidance.

Regards--

>>18497769 I've had it for two years now, it's trouble-free, economical, recommend it

Hello, the boilers purchased are working without complaint or any problems. It was a good purchase. Regards to all who took the time to help me .