Modernizing Boiler Room: Adding Coal Stove to Gas Furnace in Closed System

Hello

I have planned modernization of the boiler room and, therefore, I ask interested parties to correct my scheme
I currently have 2 furnaces, of which the installation works in a closed system on a gas furnace, I would like to add a coal stove to the installation.
I would like the coal furnace to be responsible only for central heating, when heating with a coal boiler I will turn off the valves in the gas furnace and turn off the central heating operation, it will remain only as water heating
my questions:
1.Currently, the pipes for radiators are pex 25 as a riser, for modernization I will use copper - for CU 28 boiler circuit, for circulation after 4d Cu 22 valve - will the diameters be ok? At home 5 radiators in the rooms, 2 ladders in the bathrooms, floors on 3 rtl valves (2 bathrooms + kitchen) with a total area of 23m2, the whole house 120 m2
2. Placing the safety group on power supply? Does the safety group have to be at the highest point of the boiler room?
3. How to choose an expansion vessel for safety group? From what I know is 8% of the total water in the system. Or should the container be on the return to the valve with a vent on the supply?
4.Positioning the pump on the flow? maybe it would be better if it were on return then it would work both on the boiler circuit (smaller) as after the 4d valve, if it is after the 4d valve then the boiler circuit remains gravitational
5. Will the differential valve in the event of a power failure in such a system fulfill its role if it is behind a 4d valve?
6. I would like to use the Euroster E11M controller to control a coal stove - is it connected correctly?
7. Is the cooling valve properly connected?

Thank you in advance for your time

Basic question. What coal boiler? If it is a closed system there will be a place for coils and there you will connect the valve.
If the boiler circuit is to be CU 28, there must be a pump on it. It won't go on gravity. There will be no increase in the boiler return temperature. CO circuit give 28.
Security group back.
8% is for an open system. For closed it should be more.
If the diameter of the boiler circuit 28 there must be two pumps.
If you manually switch it to full flow it will work.
As for the driver, I will not say anything. I don't have time to read his instructions.

Thank you very much for your interest. Unfortunately, the boiler is, say, noname Polish production quite small, maybe from 8-10kW, maybe replaced in the future with a new one, I can not pull the expansion vessel open anymore; / hence the need to make a closed system
Exiting the furnace and returning 2 ", hence my colleague gersik made me realize that for such an installation to work by gravity, I would have to have a 2" pipe before the 4d valve and it would be best without elbows or using a second pump for the boiler circuit, which would involve large expenditure on the pipe itself . Thanks to a colleague gersik I came up with the idea of protecting the return by using a 3d valve, I found an example of a return protection scheme on the Euroster website, I would like to ask you to check such a scheme. In this arrangement, I think I could use CU 28 pipes (which I had from the previous installation)

Have you already purchased a 3d valve?
To properly perform this installation, you should connect both systems through the exchanger. Coal boiler in an open system and gas boiler and radiators in a closed system. There is no other CORRECT implementation of this installation. I think that not many people will want to help you.

I have nothing but furnaces and Cu pipes, as I wrote, I have no way to lead the open expansion vessel above the highest point of the installation. I do not know if it was read that the installation will NOT go in parallel with a gas + coal stove, so I drew the valves on the diagram to show that it is either coal or gas heated. Only hot water will be heated by a gas boiler, but in this vandman it will be able to do it independently of CO

When making two arrangements (closed and open) you do not need to mount the vessel in the attic. It can be in the boiler room. However, you must have an exchanger.
http://3.bp.blogspot.com/-JaaTGPK1Pzc/TiLBHEz...AAAAAAAAMVY/HZ7p8OSsJYw/s1600/embed.php-5.jpg
http://test5sdkfsdf.blogspot.com/2011/07/raz-na-wegiel-raz-na-gaz-dwa-zroda.html

Well, I was just reading the truth, in fact I already had 2 installers "passers-by" and as I prompted, they did not mention anything about the exchanger - ahh those professionals . Returning to the subject of the scheme, as for me, a great overflow vessel I was left with, I thought it would no longer be useful. Installation in such a system would be the simplest and cheapest for me. In this case, it shows its diagram, as I wrote after leaving the furnace, pipes reduced to CU 28. In the installation there will be about 150 l counting both stoves and water in the pipes and radiators, so the overflow expansion vessel 15l is probably just right. 19kw gas furnace, coal 8-10 kw, so 20 KW heat exchanger will be good? And the assumption of burning in a coal furnace is that the shut-off valves from the gas furnace must be open, the furnace has a built-in diaphragm vessel and a safety valve. Last request to check the installation pattern
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This is how it should look like. You must agree with the contractor.

Added after 2 [minutes]:
And if you want to protect the return to the boiler it should be a little different. pump with a 3d valve on the return in an open system before the exchanger.
You can also do it with the pumps by regulating their power.

The contractor is me for now With such an exemplary scheme, it will not be difficult to make it, generally speaking I have a scheme for installations without return protection, I am asking for assessment with return protection using a 55 degree thermostatic 3d valve.




If you could still ask, I would like to know how to choose a heat exchanger? As I wrote, water in the installation and both furnaces about 150 L, coal furnace 8-10 kw, gas oven 19kw, 20 kw exchanger enough?

Well, only the check valve should be at the pump.
Added after 1 [minutes]:
I have a boiler 14 and a 20KW exchanger. Sufficiently no problem.
The return pump has a vessel problem. It may be too low. According to the standard, there should be 0.7X pump lift height, i.e. if you have a 40 pump, it is 2.8m high.

Thank you very much for your help, I close the subject. Regards