Downstairs toilet won't stop filling, upstairs toilet won't fill

It is a problem with the water inlet valve

https://www.plumbersforums.net/threads/how-to-stop-saniflo-toilet-water-running-into-toilet-bowl.106308/

More here.

https://www.google.com/search?q=Saniflow+Sanistar+wall+hung+toilet+won%27t+stop+filling+bowl+with+water


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Complicated from your description, it's that noise.
I think the problem is from the water heater circuit, the water in it goes somewhere lower, and the air tends to take its place after a period of time, so it is possible that a tap of hot water drops inexorably, or even a pipe warm water that is not well laid, rusty, cracked in the wall, which drastically removes water, you have sealed the cold water from the tap, so the water has no way to get in, and thus takes air due to the depression in the pipes, just like when you empty the bottle goes down, releases a characteristic sound when emptying, the water stops a little, the air goes in, the water can go down again, the cycle is resumed, etc., and that noise is what you are describing.

to much water pressure on the water line. or the valve is very sensitive. either way no danger just annoying, you can adjust the float this can sometimes stop the pipes banging.

replace the fill control as there is a failing of the control rubbers .

check the overflow pipe in the cistern tank as some fill valves do not stop completely but allow input of water after the noise has stopped. This allows the water level to rise up and the water to flow out into the toilet bowl. Reduce the water level height by adjusting the cut off level and when the water rises past the new level the increase pressure on the valve will shut it off.

Sounds like the washer in the shutoff at the wall has failed and is partially blocking the fill pipe. Some rubber from it may have gotten into the toilet valve internally. With the wall valve closed, try to remove the connection pipe to the toilet. If you can do it without water continuing to flow out of the wall shut off...then remove the pipe from the wall shut off. Flush the toilet. Now, apply air pressure to the rubber hose the goes into the overflow pipe. That may clear the valve in the tank and solve both problems. If you cannot stop the water at the wall shut off, close the water valve feeding the house. Remove static water pressure by opening the cold water a the kitchen sink faucet. Now you can open the wall shutoff valve and replace the washer and clean it out....

It could be a blocked vent.when the downstairs toilet flushes it draws air down the drain with the wastewater. The vent is suppose to supply air to make up for this. If the vent is blocked or there is no vent. Air is drawn from the easiest place ,in this case through the upstairs toilet,drawing the water out of the toilet trap with it. In northern climates the vents sometimes frost shut causing the problem you describe. Hope this helps.

Probably heat trap nipples, or other constriction in pipes.
http://waterheatertimer.org/New-water-heater-making-noise.html
http://www.thetankatwaterheaterrescue.com/forums/forum3/
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What you have going on there is called water hammering. The water flows at full force to fill the toilet tank and when the valve shuts the force that is created rattles everything. Begin by seeing that all of the nearby water pipes are secures to the wall or ceiling and not flopping around. Pipe straps available from any hardware are an easy fix for loose pipes.

And, in case you need to know more about water hammering solutions go to my link:
http://www.naturalhandyman.com/iip/infplumb/infwatham.html

it sounds like one or more of your shut off valves has a glog from hard water calcium. were from indiana its a big problem here.To check this u will have to shut off main water supply and remove top of shut off valve and check for white crusty blockage, even if u see a few particals its present. It can severely restrict flow.