Some mornings I go up to the roof of our building, open the lid of the water tanks, press down on the floating ball which opens the valve but see no water coming up. The same occurs for all 7 tanks (one for each apartment). The water tanks are always full though. I've told the plumber and he told me not to worry about it unless the tanks are not full.

I suspect that the pump controller's set point is very close to the actual water pressure of the column between the roof and the pump, so when someone is drawing water directly from the pump (we also have direct connections from the pump to each apartment) then the pressure drops a bit and the water cannot reach the roof. Or simply the controller is malfunctioning.

Anyone has any idea what's going on?

Our water pump is equipped with the PRESSCONTROL water pressure controller. I paste below a photograph from the manufacturer. In its documentation I see that the set point is not configurable but comes preset from the factory. My problem is that I can't tell what this set point is. There is no indication on the device that I can find. Does someone know any such indication? It appears to be a very popular device.

enter image description here

1 Answer 1


If the tanks are always full, this is an indication that the pressure switch is configured to turn off the pump when the column of water in the lift pipe reaches the height you see in the tank.

You can perform testing by manually removing water (draining) from the tank, which would reduce the water column height and trigger the pump.

Additionally, but with much more effort, one could raise the pressure switch a given amount. For example, if the switch is elevated by 1 meter from the current location, the column of water in the lift pipe is reduced by the same amount. This should result in triggering the pump until another meter of water is added to the tank level.

I agree with the plumber in that you have not described a problem. Consider to observe the pump/switch/tank activity when water is being used by the inhabitants. You should observe a tank water level decrease, along with the switch recognizing the reduction in column pressure. This should be followed by pump activity until the level reaches the current/existing full level.

The ad copy page I found indicates that this device is designed to be used in-line as an on-demand pressure-increase device. The specifications read a maximum pressure of 12 bar, which converts to 122 meters of water column. If your tanks are at that level, you are reaching not only the float-cut-off water level, but possibly a pressure limitation within the device.

The technical data sheet for the device indicates a maximum height of "40 mt" which I interpret to be 40 meters. Other information shows a maximum pump pressure of 5.5 bar for the highest performing pump. Another reference in the document suggests an "R" model with adjustable restart pressure.

You may not have a problem.

  • When I open the lid of the water tank and push down the floating ball with my hand, this opens the valve. Why is water not flowing then?
    – george
    Jun 16, 2022 at 6:21
  • Have you observed the conditions in which water does flow? I think the answer to that is an important factor.
    – fred_dot_u
    Jun 16, 2022 at 8:18

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.