calculating water pressure

[nickdesign]

hi guys,

is there a simple way to calculate what my hot and cold water pressures are at the tap?

can i time how long it takes to fill a litre container or something? not sure how to work it out?

 

[Agile]

You cannot work out the pressure at the tap. It depends on the supply pressure from the Water Supply Co. It will also depend on the flow rate and on local demand.

One might ask why you are so keen to know what it is! You can measure it with a gauge available form several places. But it will vary according to the flow rate that you are taking.

It would be better for you to tell us just why you think that knowing it is going to be of any use to you!

Tony

 

[nickdesign]

thanks for your advice, even if it was in a (somewhat hostile) response.

As a homeowner looking to purchase new bathroom fittings i need to find out what the water pressures I have are to determine if the fittings i'm looking at are suitable or not.

Whilst I don't profess to be a plumber and am certainly not planning on undertaking any work myself, i do like to learn and understand new things.

please let me know if this meets with your approval or not

 

[Agile]

My advice is plain and factual.

If you are planning to use a plumber then you should take his advice on what to buy.

Only if you have a combi boiler or an unvented cylinder will the H&C pressures at the bathroon be based on mains pressures.

As I said before, the only way to know the pressures is to measure them. Since they will depend on flow rate then they need very careful consideration by an experienced person.

The static pressure is irrelevant!

Tony

 

[tonybhoy]

Simple

You have either high pressure or a mix of high and low.

Tank fed hot water and cold mains will be mixed with the mains a min of one bar and the hot about 0.4 of a bar depending on the height of the storage tank to the lowest point tap in your house.

Mains cold and combi boiler UV cylinder etc will be high pressure again a min of 1Bar on both with anything up to six bar or even greater.

 

[nickdesign]

thanks very much tony!

 

[tonybhoy]

thanks very much tony!

No problem

 

[andytheplumber]

Why not use a pressure gauge.

 

[tonybhoy]

Need to qualify my previous post slightly.

If your bathroom is tank fed to both hot and cold in the bathroom then it's low pressure anything else is as above however with an UV setup the max pressure will be 3Bar or should be because a pressure reducing valve should have been installed which ensures a constant pressure to both hot and cold supplies of about 3Bar but usually 2.5Bar.

In the UV set up or a combi set up you have high pressure.

On some installations however,large council house estates on hills for example or some private 1960s type blocks of flats,even the cold water supply to the kitchen sink is tank fed so the entire house plumbing set up is low pressure.

Tony.

 

[ChrisR]

If you can fairly easily stop it with your thumb, it's low pressure. If you can't, it's high.
Mains is high, loft tanks is low.
1 bar is 10 metres height, so water from a tank one floor up is only about 0.2 bar.

OK?

 

[Onetap]

Mains is high, loft tanks is low.
1 bar is 10 metres height, so water from a tank one floor up is only about 0.2 bar.

OK?

True.
The 'low' pressure at the bathroom fittings is not a problem if the pipework is sized accordingly and the correct fittings installed. You will usually get a flow rate greatly in excess of the IoP recommended minimum, with the storage tank in the loft directly above the bathroom.

European and US practice is to have all fittings supplied from the mains.

EU-made fittings can be imported and sold throughout the EU; European installations are usually all mains supplied via unvented DHWS cylinders or combi boilers.

The problem arises if someone buys Euro taps or expensive 'designer' HP taps and then gets a plumber to fit them to a LP UK system.