how to figure actual gpm on chilled water loop

[chillered]

i need a easy way to figure gpm on my primary chilled water loop. any ideas i have asked this before and never really got a good answer.

[ruud-man]

The components such as pumps, chiller barrel, etc in the primary should give you gpm for a given pressure drop.

Good look...

[hvacpope]

why dont you install a gpm meter?

[onesidedcoin]

Every pump has a curve.Use good gauges.

[joeywpittman]

why don't you search this forum for past questions regarding finding GPM !

[tech cr]

Originally posted by chillered
i need a easy way to figure gpm on my primary chilled water loop. any ideas i have asked this before and never really got a good answer.

...what part of the loop do you want? Usually the main concern is across the barrel or cooling units.

[shogun8]

Originally posted by chillered
i need a easy way to figure gpm on my primary chilled water loop. any ideas i have asked this before and never really got a good answer.

For design conditions it's: CHILLED WATER TON = GPM x ÄT x 0.4167 or GPM = 24 x TONS / ÄT

[kwillmech]

Contact the chiller manufacturer and request a flow curve for your chiller. You will need to determine pressure drop across the evaporator then plot it on the flow curve. This should tell you the gpm through the chiller evaporator. Pump curves will also work if you don't have pressure gauges or ports at the evaporator. Try to use the same gauge for both pressure readings and make sure the gauge is good. Most flow curves will read in FT of Water or Ft Head. You can convert your pressure drop (or delta P) to Ft by multiplying times 2.31.

ex: 10 x 2.31 = 23.1
ÄP x 2.31 = Ft H2O


Hope this helps.

[ralphtheplumber]

Originally posted by chillered
i need a easy way to figure gpm on my primary chilled water loop.

Just to clarify..

Are you wanting to know how many GPM you need for a certain size chiller, or are you looking for a way to measure what you've got?

1. 2.4 GPM/Ton @ 10º dT.
2. Pressure drop across barrel.