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View the thread, titled "good pressure but poor mains flow?" which is posted in UK Plumbers Forums on UK Plumbers Forums.

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WaterTight

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At all outlets. Combi. Every tap performs like a tank-fed one with relatively decent head. But you'd never guess it was mains. My mate has a thing you attatch to a washing machine hose and it measured it at 3 bar.

Thoughts on why such unimpressive mains flow? Poor supply pipe from street? Combi prob?
 
Well sounds like a restriction somewhere,reducing flow rate , when you turn tap on do you get a good flow for a second or two and then dies down to the flow you describe ?

Maybe check with a neighbour and see how that is and perhaps compare to give you a better idea of what problem may be

imho
 
Is that 3 bar standing pressure , does it also check flow rates , most combis look for about 12ltrs at 1 bar as a rule of thumb , if you can check on this it would help , depending on where you live ie area and location like on a hill , then you have to think about where the pumping station is, to be honest 3 bar standing sounds pretty low usually between 5 and 7 where i live, ( when i was gb contracting we were not allowed to install a combi with poor flow at 1bar)🙂
 
we didn't measure flow rate, you could just see it was poor. it only measured standing pressure. i thought 3 bar was standard standing pressure? am i thinking of 3 bar working pressure then?

been asked to fit a bar mixer shower which requires .5 bar minimum which is why we checked. is it going to work do you think? what would 3 bar standing equate to in working?
 
It doesn,t equate to anything , you could have as little as 0.5 at 12lts or as much as 1 you really need to check it, if your gauge dont do it try a combi cup possibly but it will only tell you flow not pressure😛
 
I think when you say the pressure is reading 3bar, this is the static pressure and not the flow rate.
 
3 bar is fine for pressure. You probably have a 1/2" lead main and it is crushed that is the usual.

If however you have a decent size main coming into the house it must be obstructed in someway no question with 3 bar it would be unusual if 3 bar didn't deliver 20 -25 litres per minute at least.
 
good pressure does not always mean good flow. imagine a high pressure and a very small pipe, alternatively a small pressure and very large bore pipe. my guess would be a restriction or small lead main
 
Have you checked that the stop taps - including the water companies - are full open?
 
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