Will flow rate give an indication of minimum pressure?

[mcb7]

I'm thinking of replacing a shower that is fed from an immersion tank with an electric shower because the tank is not very big so the HW runs out quite quickly. The problem is that it is in a studio in a block of flats in France and so I have almost no knowledge of how the water supply works. I won't have access to a pressure gauge when I next visit but my recollection is the cold water supply is quite powerful.

I've seen that all the electric shower units I've come across say they aren't suitable for a low pressure system but I'm wondering if I measure the flow rate (from say the kitchen tap) I can make any assumptions about the minimum pressure? Even if it is only a very rough guide. And if so what kind of flow rate would I need, to assume the pressure was enough for an electric shower unit.

Thanks, Mark

 

[Madrab]

Take a gauge with you??

No real comparison to be made between flow and pressure without some headache equations and starting figures. Each electric shower will have a minimum head and flow requirement.

1bar @ 10L/Min dynamic is a good starting point.

 

[mcb7]

Take a gauge with you??

Main problem is that I don't know where I would connect it. There's only a toilet, 2 sinks, the bath/shower and the immersion tank connected to the water supply. As I understand it most gauges have a screw connector. (Plus it's France so I don't know if the fittings are the same sizes as the UK)

No real comparison to be made between flow and pressure without some headache equations and starting figures. Each electric shower will have a minimum head and flow requirement.

By head, do you mean pressure? I'm assuming the pressure is mains pressure as I doubt very much the block of flats has a supply tank.

1bar @ 10L/Min dynamic is a good starting point.

Thanks. To measure dynamic, would it just be necessary to have one other tap open at the same time?

 

[Madrab]

Some have screw connectors, others have overtap connectors. If it has a screw connector then get a 15mm>3/4" male iron, small piece of 15mm pipe and then a push fit coupler. If a push over tap connector then a 3/4" male iron will fit into that too. Not sure of France's pipe diameters though as I believe they are different , someone else may be able to advise on that.

Yes - head of pressure

Dynamic is when water is running so yes, measure when another tap is open

 

[Dan Robinson]

The Frenchists tend to have pretty high pressure.

 

[AGAS]

start from ? ( mira ) 0.7 for 7.5 kw then goes up depending of shower power of shower

 

[AGAS]

Not sure of France's pipe diameters though as I believe they are different , someone else may be able to advise on that.

inside diameter 10-12-14-16 and others i don't know

 

[picasso]

Rule of thumb, put your thumb over the tap outlet, (geddit thumb oh never mind) if you can stop the flow the pressure wont be enough for a shower , if you cant stop the flow pressure will probably be ok.

 

[Mikefromlondon]

A very crude way to test if the water is being fed from a tank as opposed to mains direct without a proper Pressure gauge is to place your thumb on the shower water outlet, and a moderate thumb pressure would enable you to stop any flow out of the tap or shower outlet if it was being fed from a storage tank, if the water is difficult or impossible to stop even by a lot of thumb pressure then you have full mains pressure present, but what flow rate you have you can measure it in a given time in a bucket and measure how many liters you collected in a minute or half a minute, and compare that with your kitchen sink tap for the same given time and capacity. You could then work it out roughly if you have a good working pressure from these two simple tests to determine if your shower will meet this criteria.

Another method is to use a party balloon and observe how quickly it gets filled to a bursting point in your kitchen sink and how long it takes to a bursting point in your bathroom shower, this could give you a rough indication if you have very similar flow and pressure at both taps, the balloon would take approximately same amount of time at both taps, except allowing a small height difference due to level between kitchen sink and bath outlet. The balloon in your bath should take a tiny bit longer to fill to same size as it does in your kitchen sink.

 

[Dan Robinson]

FFS.

 

[AGAS]

 

[AGAS]

my recollection is the cold water supply is quite powerful

just crack on op and install it , its a electric shower ,if above

 

[Mikefromlondon]

Aah so you never filled party balloons with water, must have had a boring childhood, we used to fill them up with water from a tap and smash in face of anyone came in sight and run off giggling, please don't laugh out mad and kill yourself!

 

[AGAS]

couldn't do that shyte when at boarding school (from 8 years old ) more like scrub a sports hall with a toothbrush ( and thats true )
why you taking the p&ss

 

[AGAS]

please don't laugh out mad and kill yourself!

no i won't because i would have loved to see you try it ,