Comparing shower flow rates

[HardwareGeek]

Just had an 210l unvented cylinder installed running at 3.5bar and flow rate overflowed the measuring cup so 23l/min+ afaik

Now looking to do the bathroom and want a powerful shower to make the best of the unvented cylinder.

i looked at the usual recommendation on here of an aqualisa quartz or similar and thought the mira platinum looked better, these give flow rates of 16l @ 1bar but is there a way to find out what the flow would be at 3.5bar?

Also how do you compare a thermostatic mixer that gives the flow as 8.4l @ 0.1 bar to the above to find the best flow at 3.5bar etc

 

[DavidMarq]

As a general principle when comparing a like for like systems the flow squared is proportional to pressure drop . Double the flow and the pressure will increase by a factor of 4.

So if you have a flow and two known pressures drops then you can use:

Where p=pressure & q=flow

SQRT(p1/p2) = q1/q2

SQRT(3.5/1) = q1/16

q1 = 29.9 l/min for the shower.

Which would give a flow of 49.7 l/min for the thermostatic mixer which may be ambitious as I suspect it would not have a linear curve across such a wide pressure range.