3 bar pump.

[secret squirrel]

If you have a 50 gallon cold water tank,

a 900 x 400 hot water cylinder,

water supply to tank 15mm @ 3 bar.

This system running 2 x power showers both being used at the same time on a 3 bar pump. (providing only the showers are used) I am sure at a certain point the cwst will run dry.

How long would you have before the inevitable happened?

Is there an equation to work this out?

(I know the 50 gallon is not enough, its just a hypothetical situation, its playing on my mind, which is troubled enough most of the time)

 

[bobpape]

All water flow through pipes is theoretical because of bends fittings etc
so the simple nuts and bolts approach is simply to measure it with a stop watch and
a gallon can or a two gallon bucket,
and extrapolate the results,

 

[secret squirrel]

Thanks Bob,

This has raised another issue in my head (I'm sure I can feel the monkies jumping about)

I know you want as few bends and elbows as possible (restrictions) but when working on unvented a 90 degree bend is equal to 800mm and an elbow is equal to 1000mm would this be a good rule of thumb for a run from a cold water tank?

 

[migoplumber]

the rule of thumb is to allow 25% extra on top of your pipe length for fittings. same as a price estimate for the work. some people are advised 33%

its very general, and if you want to be that precise, you need to do all the calculations seperatley.

shaun

 

[stevetheplumber]

If you have a 50 gallon cold water tank,

a 900 x 400 hot water cylinder,

water supply to tank 15mm @ 3 bar.

This system running 2 x power showers both being used at the same time on a 3 bar pump. (providing only the showers are used) I am sure at a certain point the cwst will run dry.

How long would you have before the inevitable happened?

Is there an equation to work this out?

(I know the 50 gallon is not enough, its just a hypothetical situation, its playing on my mind, which is troubled enough most of the time)

put a litre jug under the ballvale and time it to 1 litre
run both showers simutaniously and get a time for 1 litre from each
then do the maths
example

tank fills at 10 litres a minute
showers together flow 20 litres a minute
tank is therefore losing 10 lires a minute
450 litres in tank(50gallons)
450 divided by 10
=45 minutes to empty tank

 

[secret squirrel]

Thanks all,

I don't know why but I thought it'd be far more complicated than this, with equations and stuff.

 

[Plouasne]

put a litre jug under the ballvale and time it to 1 litre
run both showers simutaniously and get a time for 1 litre from each
then do the maths
example

tank fills at 10 litres a minute
showers together flow 20 litres a minute
tank is therefore losing 10 lires a minute
450 litres in tank(50gallons)
450 divided by 10
=45 minutes to empty tank

Could somebody please check the maths, I thought that 1 gallon = 4.546 litres approximately

50 x 4.546 = 227.3