In my place, the city water system provides the water at pressure of between 2BAR - 4BAR. We live on the 3rd floor, with water boiler on the roof (5th floor) so the hot water are going up to the roof and coming back down, many times without a good pressure for a good shower..
The obvious idea is to add an electric water pump on the line to add pressure whenever someone is opening the tap. For some reasons, I want more sophisticated idea, that I think will be more reliable and helpful.
My idea was to add a pressure tank (like expansion vessel) with a bladder or diaphragm on the line (before the water boiler tank). To its "air side" (bladder or diaphragm) to connect air compressor with a dynamic proportional pressure regulator.
At some times on a day - the pressure regulator will let the air pressure in the bladder/diaphragm will let the air pressure drop down to 2BAR, so the water will come in from the city system (using the 'native' pressure, without a pump help). Other times, the air pressure will be raised to about 6BAR, pressing the water towards the home, and if the tank has - let's say - about 200 litre, it will have very long time until the next need to re-fill it.
I thought about 200-300 litre pressure tank (will be held at about 6BAR), with air compressor with 50-100 litre air tank (at about 8-10 BAR).
AFAIK - Such a bladder water tank of 200 litre will cost here about 250$, and air compressor will cost about 150$-200$. I'll also need the proportional pressure regulator and the plumbing, but generally that's it.
Am I right?
Any insights would be welcomed.