measuring flow rate

[james2006]

Hi can anyone tell me how to measure the flow rate from the mains?

Cheers

 

[Andygasman2010]

Simply...

Take a 1ltr jug and see how many times it fills up in one minute.

Or... take a large container of some sort and run water into it for one minute, then measure how much you have.

Bobs your uncle etc...!

 

[james2006]

Thanks. Thats essentially what I did and got 13l/min. The plumber used a flow rate cup and got 20+l/min. I reckon he could have been pulling the wool over my eyes.

What would be your recomendation for new boiler system? Currently on vented, but was thinking about unvented/combi?? but flow rate is clearly an issue.

 

[mointainwalker]

I'm sure that flow-rate can alter during the day but have no idea by how much. Did you do your sampling more or less at the same time as the plumber ?

 

[Beerlover]

Nowadays, we work on dynamic flow rates, similar to gas working pressure. The reason for this is it allows some tollerance for mains pressure variations and two taps open at the same time.

It means the flow rate with a back pressure of 1.5 bar recommended (1 bar min) and the flow rate measured then. I use a weir gauge from Barco specifically for this. A decent unvented installer would have the same or similar, get an unvented hot water survey carried out; would estimate around £40 mark.