To tell if a tap or shower is fed from your cold water tank in the loft or a mains pressure pipe, the flow from that tap or shower in litres a minute will give an excellent indication as to how it is fed. This blog is dedicated to Rory, Leah, and to many other ShowerPowerBooster customers who are in doubt as to how a tap or shower is fed.

As a general rule if the pressure to a tap or shower is doubled, the flow increases by 50%. The minimum mains pressure delivered to a customers home in the UK is 1 bar which is 10 metres head. The pressure to the hot and the cold in a gravity system is determined by the height of water in the cold water tank in your loft or airing cupboard, (not where your hot water cylinder is).

In a typical home the pressure head from the top water level of a cold water tank to a tap or shower is:-

Upstairs shower – 1 metre
Upstairs tap – 3 metres
Downstairs shower – 4 metres
Downstairs tap – 6 metres

By way of comparison the minimum mains pressure downstairs is 10 metres, (upstairs 7 metres).

The first thing to note is that if a system is gravity hot and cold or mains pressure hot and cold then the flow when you turn to full hot will be about the same. If you have a mixed system then the cold flow should be much higher than the hot flow. Often this is very obvious but judging flow rates is very difficult so if its not obvious and to avoid doubt you can carry out a flow measurement test. It is very easy to do if you follow my video (see below).

Once you have carried out the test, if you are in doubt, or still unsure, please contact our Shower Power Booster customer service team to let us know the flow rates, where the shower or tap is. If you have already fitted our pump or pumps the flow rates with and without the pump or pumps running is also needed.

For good measure if you can tell us the make and model of the tap or shower we can often tell what flows you can expect from that tap or shower.

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