Condenser water temperature

[sigma]

Evaporative cooling tower has fans with VFDs. RPMs are controlled by change in water temperature.
Tower is used with R-11 centrifugals and R-22 package units without water regulating valves.
Minimum water temperature is 75F. It seems little low to me.
I realize that lower condenser pressure means lower amps on chillers but in the same time tower fans use more energy, more water is evaporated and lost to more frequent blow downs.
Higher chemicals usage is also a factor
What is your opinion? What is the lowest water temp. from the cooling tower in a chiller plants, that you see every day?

[maxster]

try 80F on the troth,and once the units start to come on and load up with the sun swinging on that tower that minimum is out of the picture.if the VFD is hovering around 30Hz that is good with the days load cycling thru the tower with room to ramp up.as for the R-22 with "no regs" they could probably do 60F inlet water with no problem.....i would babysit that R-11 and let that lead the show with what goes on with the tower troth range.once that heat goes up thru the troth after loading up,the R-22s will follow along.

[sigma]

Maxster,
Thank you for your reply. How hard is to change the setting
of VFD signal? I am not an expert in this field.

[maxster]

there must be a temperature sensor that is controlling the DC ramp to the VFD and with that a adjustable setting in degrees,there is nothing within the VFD to adjust.that 0-10VDC ramp signal from external controller with the 10VDC is produced from the VFD and ramped thru the adjustable control point 10VDC being 60Hz.......5VDC being 30Hz and so on.when you locate the controller(1)you should read a steady 10VDC(2)then read what the controller is ramping out to the VFD 0-10(3)read at the VFD that signal ramp and see the range of Hz vs the corresponding DC signal going in vs what the troth temp is!

[Edited by maxster on 07-10-2005 at 08:45 AM]

[sigma]

I will look for this controller tomorrow. If there is
an adjustment in a form of potentiometer, I will
try to change the temperature setting and see how
much this will effect chiller amps.