Minimum pressure for gravity fed shower

[Jayluvit]

Hi all,
Please could someone advise me if there is a minimum water pressure required when installing a gravity fed shower.
I am renovating the whole of my house and wish to install a gravity fed shower.
I have a cold water feed from the original pipework, which the previous owners had for the electric shower, direct from the mains with over 5 bar of pressure and 20 litres a minute flow rate.
I plan to plumb in the hot water pipework myself but the pressure from the hot water tank is only 3/4 of a bar. Not too sure on flow rate but its not as much as the cold water obviously. Its the hot water pressure I am concerned about as to whether this can sustain a decent gravity fed shower if not I will probably install a power shower.
Any information on this will be greatly received.
Jase

 

[doitall]

I doubt it's anywhere near o.75bar, which would make the storage tank 7.5 meters above the top of the cylinder.

Mira do some very good low pressure showers, but you should run the cold tank fed as well.

 

[TicklyT]

0.75 Bar is a good figure for a gravity system. Many can only manage about 0.1 Bar at a shower head.

I would prefer to see both hot and cold supplies at the same pressure, running a gravity cold feed to the shower if at all posible.
Vastly differing water pressures can make temperature control problematic for the average mixer, and may need measures to prevent the cold supply backfeeding the hot system.

We had an Aqualisa thermostatic mixer that worked well with only about 0.08 Bar at the shower head.

 

[kevplumb]

I have a cold water feed from the original pipework, which the previous owners had for the electric shower, direct from the mains with over 5 bar of pressure and 20 litres a minute flow rate.

must have been some shower heater

 

[Jayluvit]

Thanks everyone for the helpful replies.
The pressure of .75 bar I got from downstairs as there is nothing in the bathroom apart from the toilet system. I got the reading from using a pressure gaugue so it should be accurate.
I figured that a tank cold supply is the recommended route however I do like to feel my skin being ripped off when I have a shower, sadistic I know but each to their own!!!
Jase

 

[Bon]

You will never get the shower you want with a gravity system.

If your mains pressure is that good, you can get a venturi shower, which uses the mains pressure cold flow to "pull" the hot water through as opposed to relying on gravity. You would certainly need a check valve on the cold feed though to prevent back-flow.

The other option is to fit a pump.

As stated though, the hot & cold supplies should balanced (unless a venturi is used).