shower water flow rate

[tally100]

Hi

I am having a 120L mains pressure cylinder and new boiler fitted this week and i wanted to know the flow rate of water out of my en-suite shower so i can be sure the 120L is big enough, it has a 17 min reheat.My incoming mains has a pressure reducing valve and i have good presure
How do i work out the flow rate litres per minute from my shower

Thanks

 

[Bon]

It depends on what sort of shower it is, i.e. is it pumped/gravity or electric.

Without knowing these details I'd recommend using a bucket and stop-watch.

I've done this on numerous occasions when trying to size chilled water systems etc.

 

[tally100]

non electric straight from thermalstore and mixer to ensuite