[BLDG-SIM] Data source for cold water inlet temperatures

[Jason Glazer]

I received many suggestions for data sources for cold water 
inlet temperatures but the best was:

  EPRI TR-100212, December 1992, "Commercial Water Heating
  Applications Handbook" by D.W. Abrams & Assoc.

I did some analysis of that data with NCDC degree day and 
average temperature data.  Generally, the conclusion I came 
to is that average monthly and annual temperatures are no 
better at predicting inlet temperature then heating degree 
day data.  That is the not what I expected. The R2 
(goodness of fit) that I was getting are in the 0.4 - 0.6 
range, not very good but expected.  Here are the equations 
I'm planning on using:

  maximum inlet temp = -0.002860 * HDD + 87.8

  average inlet temp = -0.003161 * HDD + 74.3

  minimum inlet temp = -0.003135 * HDD + 59.3  

Where HDD is the annual heating degree days base 65.

As you can see the slopes are about the same but the y-
intercepts are different.  For those who want to explore 
the number some more, my spreadsheet is attached.

Thanks to all who gave me references!

Jason


On 23 Dec 2002 at 16:11, I wrote:

> I'm looking for a data source for typical inlet water 
> temperatures (water main temperature) for residential 
> service water heaters for locations in the United States. 
> This is roughly equivalent to the ground temperature at 6 to
> 8 feet depth. The temperature varies seasonally so knowing
> the average monthly value would be best.  
> 
> I am already aware of two sources of data that don't really
> help: Engineering Weather Data from NCDC has the 50 ft
> temperature and the map in the old ASHRAE Load Calculation
> Manual is for depths of 4 inches. 
> 
> Any leads would be appreciated.
> 
> Jason
> 
> =========================================================
> Jason Glazer, P.E.  mailto:jglazer at gard.com  847 698 5686
> GARD Analytics - http://www.gard.com/ 1028 Busse Highway,
> Park Ridge, IL 60068 Building Energy Simulation and Analysis
> Admin of BLDG-SIM list for building simulation users
> 
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=========================================================
Jason Glazer, P.E.  jglazer AT gard DOT com  847 698 5686
GARD Analytics - http://www.gard.com/
1028 Busse Highway, Park Ridge, IL 60068
Building Energy Simulation and Analysis
Admin of BLDG-SIM list for building simulation users




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