# Pool Evaporation



## mechgirl (Mar 23, 2010)

I'm working the HVAC 6 min solutions, on a pool evaporation rate problem (#36), and it refers to ASHRAE for the equation used. I can't find this equation in any of my ASHRAE handbooks. Can someone point me to it?

Thanks.


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## MechGuy (Mar 24, 2010)

mechgirl said:


> I'm working the HVAC 6 min solutions, on a pool evaporation rate problem (#36), and it refers to ASHRAE for the equation used. I can't find this equation in any of my ASHRAE handbooks. Can someone point me to it?
> Thanks.


I remember this problem. I think the equation is in the ASHRAE Applications Handbook. I can look when I get to my desk in a few hours. But a quick google search for "pool evaporation ASHRAE" gave me this equation:

Wp = 0.204 * A * (Pw - Pa)

where

Wp = rate of evaporation (lbm/hr)

A = pond area (ft2)

Pw = sat. pressure of pool water (psia)

Pa = sat pressure of air dew point (psia)

I'll verify from my ASHRAE book in a bit. Hope this helps!


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## MechGuy (Mar 24, 2010)

MechGuy said:


> mechgirl said:
> 
> 
> > I'm working the HVAC 6 min solutions, on a pool evaporation rate problem (#36), and it refers to ASHRAE for the equation used. I can't find this equation in any of my ASHRAE handbooks. Can someone point me to it?
> ...


OK I looked in my 1999 ASHRAE Applications book, and the equation for pool evaporation can be found in Chapter 4, "Places of Assembly", under "Natatoriums." The equation listed there is a bit different than the one I found from Google. So go check there and you should be good!


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## mechgirl (Mar 24, 2010)

I found it. Thank you.


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## Bman (Mar 24, 2010)

Thanks Mechguy! I couldn't find this either and ended just looking at the answer and adding the equation to my equation sheet in case I needed it again.... Good to know where the info is at though, there were two questions in the 6 min HVAC book that deal with pool evaporation.


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## MechGuy (Mar 25, 2010)

My pleasure. This is one of the reasons I think its important to have all 4 ASHRAE books at the exam. You never know what random question will show up, and if these books help you answer just one question, it's worth it. Might be the difference between a 69 and a 70!


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