greetings cecy, adding to the comments by servimat1 (greetings) .is possible : D there are deposits or impurities in the pipe and therefore no water comes out : D the inlet pipe outlet towards the boiler does not have the same level and in crockery or in some parts it goes up and down allowing the air to accumulate and not run the water ,, I have seen this in several houses and it is only solved by placing at the level of the pipe, sometimes a simple thread placed at the ends and along the pipe allows alignment : D the air jug is not well installed (air breaker, respirator, etc.), sometimes one to one elbow is uneven and a bubble is formed making it difficult to work well ,,, Usually it should be in the part where the pipe goes down to bathrooms, kitchen or area where they will use the water and will have a tube that allows the existing air in the pipe to escape and allows the water to flow quickly :( you will also have to remove a shower, shower or flower shower bath and see if enough hot water comes out, sometimes they have flow reducers and this prevents water from leaking out, in my case I remove rubbers or enlarge hollow using flat screwdriver or paddle or some proper tool : D remember that in the kitchen faucet, in the washbasin faucet, there are filters at the tip of the faucets, this may in case of having grit or earth cause water not to press out, that is, it reduces flow : D if you want to test if there is air in the pipe, it is enough to place a transparent container or jug and let the water run, you will see that air comes out, if you want to speed up the process you can apply air in cold water hoses and after a few attempts it You will see how the water will take pressure ;) this will be provisional and then it will fail again but lets see that it certainly requires repairing air jugs or pipeline breathing luck