Water pressure

[Chancer]

I have relatively low water pressure of 2.8 bar despite being 25 metres below the very tall chateau d'eau in our village, it has been suggested to me that in since the rocade was built we are no longer supplied from this as it was considered to be at risk.

I will do some checking but it looks like I am probably stuck with what I have, my problem is with the highest of the flats that I am building, those in the grenier will only have a water pressure of 1.8 bar, is this realistically enough for a shower assuming suitable pipe sizes?

I am on the ground floor here and 2.8 bar is OK, my place in the UK has 6 bar giving a very good shower but explains why the group de securité is leaking, I reckon 1.8 bar is going to be pretty weedy but can anyone confirm this?

[BIG MAC]

If it isn't  enough for your purposes you could simply put your own holding cistern in.

[Le Plombier]

1.8 bar is plenty for a shower

French mains pressure is circa 6 bar but a pressure reducing valve should be fitted to reduce the pressure to 3 bar at the entry to your property

In the UK properties with roof cold water cisterns have only about 0.5 bar pressure for the shower, with a booster pump fitted they achieve about 1.5 bar and a good shower pressure

Install your shower, use 16mm connections and see what the result is, I am sure you will get a decent shower

Le Plombier

[Chancer]

BigMac

What do you mean by a holding cistern, a loft header tank? - A bit difficult when the flats concerned are in the loft! Or pehaps you meant a surpresseur which was one option that I considered.

Le Plombier, thanks for your figures, I think that I will hedge my bets by fitting baths due to space and height constraints, these will have plumbed in shower roses, the big bowl type so even if the water only trickles it will be like a tropical shower if you get my drift, at least I wont have problems with water splashing on the sloping section of the ceiling (the bathrooms are tucked in les combles) with that type of set up.

Your reply has boosted my confidence if not my water pressure.

I recall  how weedy my shower in the UK was with I calculate to be about 0.2 bar of static head, it's certainly much improved with a pump, its interesting to now know what pressure it is developing, the best one of all is in an outbuilding that I converted to be my pied à terre, I used a French ballon and hydro-jet shower and it is like being whipped by birch twigs, having recently measured the pressure at 6 bar I know know why, time to fit a detendeur I think. 

[BIG MAC]

Hi JR along those lines. French don't like vented systems though and as you are in the loft already then optuons this way are limited unless you have a Mansard roof which would take a tank/cistern. You will have trouble with pumped showers in a sealed system but as LP says you should have adequate pressure anyhow.

You could look at  splitting incoming services and putting each floor on its own pressure reducing set up to allow yo to make the best of what you've got available otherwise the spectre of  demand from lower floors may make for  weedy services above. If you do go for some kind of vented arreangement then why not have lower floors tanks located in the floor above  (I have used stairwells for this in the past creating a serviceable tank space on the landings) and put the Attic on mains direct? Really without seeing what you have got and not being aufait with French rules it's all a bit of a guess.

[Chancer]

Food for thought BM, thankyou to both you and Le Plombier.

I have done a few checks and I think that there may in fact be a simple explanation and I need to make enquiries at the Mairie rather than follow the often erroneous local gossip.

If I were indeed connected to to our chateau d'eau I would have at least 6 bar as I am 25m below it, local opinion has it that we are no longer connected to that but to the reseau of the next two downstream villages explaining of course why our water costs so much [blink] -oh how many times I have heard that one trotted out regarding taxes foncieres etc always speaking ill of the Maire.

However now having measured the pressuer there at a healthy 6 bar, even allowing for the 5m elevation of my village I would have 5.5bar.

Do they fit reducteurs de pression at street level? Perhaps on the lowest streets like mine, or is it possible that there is one built into my very large compteur? -There is no obvious sign of one

I still have a lead pipe feeding my property, could this have some bearing on it?

[Anton Redman]

Unless the water pressure declines sharply when a tap is turned on I do not think you should have a problem. 1 Bar equalls about 33.5 feet of water ( varies with temperature ) . In the UK we ran a perfectly satifactory shower with a head of just over five feet. Suggest you keep the pipes a size bigger  if you have concerns. Except for recent UK builds with pressurised systems suspect most bathrooms have only 0.3 bar on the hot feed.

[Le Plombier]

Presure reducing valve is normally fitted after the meter in the meter pit or where the supply enters the property

Reducing the pressure to 3 bar does reduce or eliminate problems with safety valves and groupe de security discharges so is better for the equipment

As you have been advised 10 metre head is equivalent to 1 bar pressure

With a pressure reducing valve fitted and 3 bar pressure in to the property, even if your property is 10m high you will still have 2bar pressure on the top floor

In regard to flushing I simply remove the filters on the taps on commissioning and make sure I run water through the taps before any other supplies such as showers

Afterwards screw the filters back on the tap outlets, quick, simple and gets all the muck out without the need for special measures

Le Plombier

[pachapapa]

A groupe de sécurité will open at 7 bar but could be as low as 6.65 bar in accordance with the tolerance permitted by NF EN1487 NF-D 36401.

Please refer to the link below for further information.

http://w4-web125.nordnet.fr/groupes_securite_fr.htm

The posts by Big Mac are amusing but not relevant to a french installation.

[BIG MAC]

A blow by valve (Pressure relief/ Groupe securite) will of course unload at the pressure at which it is set / calibrated, never presume that they are all set the same.

Pressure and volume are not the same thing so while one may have marvellous pressure at one outlet when there is significant draw off throughout a building then the call will be for an accessible volume of water (Preferably both heated and unheated while providing potable water for the morning coffee/ teeth brushing etc.)

Buildings in multilple occupancy will have significant draws at peak periods (This applies in just about every country in the World) by the time you have restricted pressure you will only be able to permit a given volume of water through dependent upon pipe sizing (tables are readilly available). There obviously isn't  an NF No. for common sense. Amusement in this regard may well be the preserve of the technically inept or the last bastion of the Googletelligent.

As for removing tap filters etc presumably for shower installations the reference is to the inline strainers which are usually located in up services but not in tap connectors. To run water through a ceramic cartridge (if the pipework is contaminated) you run the chance of catching rubbish in the tap body or the cartridge itself. By the same token running potentially contaminated water through a new boiler therefore via  the flow switch  and heat exchanger before it gets anywhere near a tap is not the correct thing to do at all and will in most cases, if discovered, will invalidate the warranty.

I am no expert in French installation or terminology however water tends to be multilingual.

 

 

[pachapapa]

A blow by valve (Pressure relief/ Groupe securite) will of course unload at the pressure at which it is set / calibrated, never presume that they are all set the same.

The valve will be set at a nominal 7 bar in france with a spring calibrated for that pressure and a plate will be included in the assembly of the safety group attesting to that compliance.

So I can make a fairly safe assumption that they are all set the same.

Pressure and volume are not the same thing ...

Quite correct Sir as a perusal of Boyles Law will confirm.

PV=RT.

Buildings in multilple occupancy will have significant draws at peak periods ...

A truism indeed Sir but any competent Installation Technician would install a pressure reduction valve for each dwelling after the consumption meter and particularly where differing vertical elevations of the residences are concerned. The pressure reduction valve fitted would also have a diameter commensurate with the anticipated consumption regime.

The abundant "multilingual rain " falling today has seriously restricted activity on my current natural hydraulic lime project, so not much to do but surf;

An inept google-intello-wallah.[:D]

[BIG MAC]

"any competent Installation Technician would install a pressure reduction valve for each dwelling after the consumption meter "

Like wot I said then...me being a competent technician may have something to do with that.

You also confuse the pressure restriction value (Which can be a variable dependent upon the type of valve) with that of the pressure at which the device will unload but no matter

"The pressure reduction valve fitted would also have a diameter commensurate with the anticipated consumption regime"

Diameter of the valve makes little odds as the device will only allow flow at the proscribed pressure however there would be little value in having pipe sizing larger than the free sectional area of the valve/s .......or  conversely a valve which presented a restriction/venturi

Anyway I am glad you appreciate my new word...Googletelligence will one day rule the World and there will be little requirement for free thinkers.....

[Le Plombier]

All too much for me, a simple plumber, I am out of here

Le Plombier

[Chancer]

And I, the OP have only ever been described as competent when preceded by "in" [:P]

It"s good fun watching two people arguing and both saying the same things!

[BIG MAC]

Oi.....you started this! besides did you say competent or continent? [www]

[pachapapa]

[quote user="BIG MAC"]

"any competent Installation Technician would install a pressure reduction valve for each dwelling after the consumption meter "

Like wot I said then...me being a competent technician may have something to do with that.

You also confuse the pressure restriction value (Which can be a variable dependent upon the type of valve) with that of the pressure at which the device will unload but no matter

"The pressure reduction valve fitted would also have a diameter commensurate with the anticipated consumption regime"

You also confuse the pressure restriction value (Which can be a variable dependent upon the type of valve) with that of the pressure at which the device will unload but no matter Anyway I am glad you appreciate my new word...Googletelligence will one day rule the World and there will be little requirement for free thinkers.....

[/quote]

You also confuse the pressure restriction value (Which can be a variable dependent upon the type of valve) with that of the pressure at which the device will unload but no matter.

No I dont the release valve on a french "groupe de sécurité" is set at a nominal 7 bar using a calibrated spring, the release pressure is NOT ajustable.

If you were to consider the safety function of the "groupe de sécurité" it would be AT LEAST IN MY OPINION rather stupid to market a product on which the specified release pressure could be changed at will.

You also confuse the pressure restriction value (Which can be a variable dependent upon the type of valve) with that of the pressure at which the device will unload but no matter 

I know not what you mean by a "pressure restriction value".

But a french pressure reduction valve is adjusted after fitting in accordance with the pressure differential required by the consumer; this will depend on the static pressure head on the supply side and the pressure desired by the consumer. By means of a simplme screw driver the consumer has the possibility of a consumption pressure anywhere between "no pressure reduction" and "effectively no pressure at all".

As an anecdote: when I have visitors from the UK, I adjust  the pressure to a VERY low value so the water in the shower just manages to get up the stairs and trickle out the shower head; in france unlike the UK the water is metered.[:D]

 

[BIG MAC]

Jeez Louise......Obtusely Googleteligent

The outlet pressure is adjustable hence why they provide a knob......resist must resist.......or a slot for a screwdriver and sometimes a nice little gauge hence a variable 'Value'

The unload pressure for the  device will be stated and calibrated and is not adjustable as a safety feature.

I can direct you to data provided by Messrs Boss or similar which will go into the intricacies of valve operation but to be frank I am not having much joy thus far so shall leave you to wind up your guests with your twiddling and annoying dribbling. I have better things to do. [blink]