Ariston CLAS EVO 24 FF - Error Code 1 08: Draining Water, No Hot Water, Restart & Valve Issues

Hello.
When draining water from the installation, the furnace was in hot water function. The CO function has been turned off.
After draining the water from the installation, during the attempt to turn on the hot water he did not give hot water. The display shows error 1 08 which is not in the manual. Reset gave nothing, disconnection from the power supply for several minutes causes the stove to start in the absence of any messages on the display. It goes out after 2 minutes, throws 1 08 error.
When the central heating valves are closed, the stove does not start. Opening the CO valves, when releasing hot water, starts the stove, but goes out after 2 minutes and throws error 1 08
What to do?

Hello.
First of all, it is forbidden to try to start the boiler even only on hot water with drained water from the central heating system! This may cause serious damage to the boiler, and even its total destruction!
First, pour water over the central heating system, open the central heating system valves, bleed it and try again if the boiler works correctly.
Error 108 means the boiler water pressure is too low.
Greetings.

THANK YOU for the urgent WARNING that prevented me from destroying the furnace.
After filling the installation with water to the correct pressure - everything started, the error disappeared.
Thanks again for your help.
Tylo

Hello. I have a question related to water pressure. I noticed leaks in the central heating system. The boiler periodically issued error 108. I added water to the system and the pressure on the manometer is now 1.5 bar, but a slight dripping from the CO pipe remained. However, it is so minimal that the pressure is okay, but I have another problem. After turning off the hot water supply, it still gives error 108 and the water runs out. Is the pressure in the central heating circuit related to the DHW pressure?

The pressure in the central heating and hot water systems is the same. It is a closed system. I understand that it is a 2-function boiler. And after turning on the hot water in the tap, it should turn on and heat the water. What happens when you turn on the tap? Will error 108 appear? What is the pressure on the manometer at this time?

Hello.
When I turn on the water in the tap, error 108 appears, but it doesn't happen every time, sometimes it heats the water, sometimes it doesn't. In the case of CO, in turn, it gives errors: no flame, flame blown out, or 108, i.e. low pressure. When I went to the basement to the furnace, I noticed water droplets on two PEX connectors and I could hear a gurgling noise in the boiler that made the chimney rumble.
A week ago, the installer replaced the pipes from the boiler to the manifold from 20 to 32 and tightened the elbows so much that it leaks. I have already written to him and he is supposed to come tomorrow and correct it.
I had to add water to the boiler twice because the pressure dropped below 1 bar. It's probably taken in so much air that it's freaking out and making various errors, which is probably where the gurgling noise comes from.
I asked the question because at the beginning I was wondering what the pressure in the central heating system has to do with the error when using DHW, but it is as you wrote.