Central heating installation - the diagram to be checked - Please check the diag

Hello,
I am asking someone who is knowledgeable in the subject to assess the correctness of the attached scheme of the CO + CWU installation
Open installation, all-flammable boiler (mainly coal, walnut and wood) 25kW. Boiler room in the basement, heated ground floor + part of the 1st floor, a total of approx. 140m2. Everything on radiators, without a floor.
The main part of the installation (all 'thick' lines in the diagram) is 28mm copper. From manifolds to 16mm PEX radiators.

The expansion vessel will be open about 5-6m above the boiler.

Basic questions:
1. Would the installation be safe?
2. Is something missing / too much?
3. Are the pipe diameters in the installation appropriate?
4. Which version will be more correct and why? In the first version, the pump and the differential valve are connected to the same four-way valve output, in the second version the differential valve is before the four-way valve, and the pump at the four-way valve output.

I will be grateful for your help

Differential valve as in version 1. Why two pumps? One on a common central heating and domestic hot water circuit without a four-way valve. No pump control after reaching the right temperature on the boiler. The tube for the dish from the highest point and can be thin. The boiler is supplied from the central heating pump before the manifold. I think the boiler is too big.

1. Installation is secure. Only the safety pipe is to be connected from above with an empty space of the expansion vessel, and from below the vessel well. So there must be a tee on the RB and the joint must be connected from the bottom and top of the vessel.
2. Check valves are to be behind both pumps. There is no need to bypass the pump on the radiator system because the system is made of manifolds (no gravity).
3. If there is no boiler pump, the installation in the boiler circuit and the 4d valve must be the same size as the boiler outlet. Certainly not 28. If you want to make a circulation and a 1 "valve, there must be a pump between the return from the 4d valve and the boiler.
4. Second version only without differential valve.

Why version 1 valve? I mean explain the differences in action.

Two pumps because if I turn the four-way valve so as to cut off the radiator circuit (summer), then the boiler circuit + DHW circuit will remain, and thanks to the pump the water will actually go through the DHW tank, and not on the shortest route on the boiler circuit itself. If I'm wrong and CWU works the same way, please correct me.

I can't get rid of the four-way valve, I care about the right temperature to return to the boiler.

The control of both pumps will of course be, perhaps the four-way valve itself, I have not only placed on the controller diagrams.

Added after 15 [minutes]:

Quote:

1. Installation is secure. Only the safety pipe is to be connected from above with an empty space of the expansion vessel, and from below the vessel well. So there must be a tee on the RB and the joint must be connected from the bottom and top of the vessel.

Apparently in low power systems the overflow pipe can act as a safety pipe. I found something like this:
.
it's the version on the right. If this is incorrect or complete nonsense then please correct me

Quote:

Check valves are to be behind both pumps.

Indeed, I forgot about it.

Quote:

There is no need to bypass the pump on the radiator system because the system is made of manifolds (no gravity).

That's right, it won't push through distributors

Quote:

If there is no boiler pump, the installation in the boiler circuit and the 4d valve must be the same size as the boiler outlet. Certainly not 28. If you want to make a circulation and a 1 "valve, there must be a pump between the return from the 4d valve and the boiler.

Could you explain why? I care about understanding the topic.

One more question - will it be warm enough there without an additional pump?

Do as you like, I do not agree with gersik. Why are you complicating this?

https://www.is.pw.edu.pl/~pawel_kedzierski/ZabezpieczenieNWotwarte.pdf
Because gravity will not work on such a small diameter of the boiler circuit, and there will be no return protection. This topic is rolled out all the time, just look.

Added after 2 [minutes]:

http://sas.busko.pl/pl/images/stories/sas/pro...rty_zamkniety/uklad_otwarty/ukl_otwarty_1.jpg
This is how the vessel should be connected.

Added after 1 [minutes]:

This installation works for my parents 10 years you close manual for summer and that's it.

Unfortunately, I will definitely not decide on such a solution. Maybe it works 10 years, but the expansion vessel connected behind the valve and pump?
The regulations make it clear that this can't be the case. Besides, I would be afraid for my parents' life when the power goes out and the valve grows stone and doesn't let go.

Yes, if you run out of electricity, you boil water. The vessel after the pump or valve is not a problem. The pump is not tight as you know its construction is a centrifugal pump like in a car.

"nowackahelena" could you not comment on heating installations?
"webfreak" do not forget about the thermometers on the return to the boiler and on the supply to the radiators behind the pump.

Ryszard_to_wie wrote:

Please do not show such dangerous schemes, someone else will use them and the accident is ready.

Why? write us all?
I remind you of an oversized coal boiler "for everything" and you can't just turn it off, and at least one receiver should work in gravity. Unless it has a second cooling coil.

In one "... helena" is right. The boiler is too big.

The house is not insulated, and I do not exclude the possibility of smoking I had, and then the efficiency will not be as high as on basic fuel, hence the boiler power. The area also may increase slightly in the coming years due to the development of most of the floor.

Ryszard_to_wie wrote:

This question has already been answered by the author himself, you can see that he is more stranger than you.

Yes. Is more.

Thank you for any advice. I close the topic.