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# BTU formulas?

Member Posts: 4
I have a customer that owns an artesian well.  This customer is a hot water utility company that distributes heat and water to various companies.  One particular customer is an industrial laundromat that uses both heat and water.    Here is the scenario; they have a line coming in at 175 degrees F at 100 gpm. The line then T's and they take hot water off this T.  Bypassing the T is the return line its temperature is 140 degrees F and the flow rate is 50 gpm. My customer wants to bill the laundromat for the use of the heated water and for the use of the heat from the returned water.  So that leads me to my questions;  Using my supply and return flow rates, how do I calculate BTU usage.  On the T where the laundromat is taking water and doesn't return, how do calculate BTU on that?   Thanks for any help and equasions.

• Member Posts: 212
BTU Meters

www.istec-corp.com
• Member Posts: 4
Need Formulas

Thanks for the links, but I need the formulas.  Especially where the water isn't returning.
• Member Posts: 5,837
Simple numbers...

Gallons per hour times pounds (8.3 per gallon, but you have to adjust for water temperature and subsequent density, which changes with temperature and is available from engineeringtoolbox.com) times delta T = BTUH.

ME
It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
• Member Posts: 4
BTU formulas?

I figured the formula would be different since there wasn't a delta T for the one problem.
• Member Posts: 5,837
Dsiplaced energy...

If the end user had to heat his own water, and it was coming from a well, at say 45 degrees F, then the energy he avoided would be based on that entering water temperature and the final water temperature. If you take into consideration the efficiency of a water heater at a seasonal energy factor of say 70% (EF-.70), then you would take the delivered BTU's, and divide by .7 to compensate for what he would have wasted in regular energy getting the hot water to that point, If your customer wants to be real nice, he could just skip the last part of the formulae...

I would then use the base cost per therm for conventional energy being displaced. If it were electricity, then it would be around \$1.50 per therm (100,000 btu's) . If natural gas, then here in Denver it is around \$0.50 per therm.

ME
It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
• Member Posts: 4
BTU Formulas?

That's what I was searching for.  Thanks for your supporting info...
• Member Posts: 36
Electricity Cost?

I thought,

If 100,000 BTU  (1 therm) and 3412 BTU per KW than

100000/3412= 29.31KW x .18 per KWH = \$5.27 @ 100% EFF

The .18 is average delivered cost in CT

Am I doing something wrong? I am no where near \$1.50
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