CASE OF TOWER BLOCKS :
Case No. 1 : 6-storey building - « Normal » water mains pressure : 6 bar - Desired pressure in each flat : 3 bar.
In the case of a residential building, it is advisable to install a pressure reducing valve at the input of each flat, and not a centralised pressure reducing valve at the bottom of the building.
Why ? : we should consider a height of 3 metres for each storey, a load loss per storey of 0.3 bars.
Therefore, if you install a single central pressure reducing valve at the bottom of the building adjusted to 3 bars, the first storeys will be supplied at the right pressure, but the more you go up the storeys, the more the pressure will drop.
For example, the 6th floor will have only 1.4 bars of available pressure, too low.
It is therefore necessary to install the same pressure reducing valve, adjusted to 3 bars, at the entry of each flat.
Case No. 2 : Building of more than 6-storeys « High » water mains pressure : 10 bar - Desired pressure in each flat : 3 bar.
In the case of a residential building where the mains water pressure is very high, you are advised to install on the main inlet a pressure reducing valve of a larger diameter, which will firstly reduce the pressure to 6 bars, and a pressure reducing valve adjusted to 3 bars at the entry of each flat.
The vertical columns are thus protested by the larger pressure reducing valve, and each level by a smaller pressure reducing valve to give a pressure of 3 bars.
Remark : For very high buildings, the highest storeys do not require the installation of a pressure reducing valve when the pressure is less than 3 bars.
Case No. 3 : Building of more than 6-storeys - « Low » water mains pressure : 3 bar - Desired pressure in each flat : 3 bar.
In this case, the installation of a pressure booster is necessary.
This will be adjusted to a value of 5 or 6 bars, the purpose being to obtain adequate pressure at all floors.
It is therefore necessary to install the same pressure reducing valve, adjusted to 3 bars, at the entry of each flat.
Remark : again, for very high buildings, the highest storeys do not require the installation of a pressure reducing valve when the pressure is less than 3 bars.
