There have been several recent posts inquiring how long it would take or how much it would cost to heat a pool / spa using a natural gas heater. In response, I have taken on the challenge of putting together this spreadsheet to help answer those questions. It’s now ready to be test driven.
The spreadsheet has two sections:
A couple of other notes:
Post to this thread if you have any suggestions or comments on this spreadsheet.
The spreadsheet has two sections:
 1. A Scratch Pad where you can estimate the hours needed to run the heater to achieve a desired temperature rise for a given water volume. There is a Multiplier Factor to account for variabilities in heating water that is subject to the elements. This is explained further in the spreadsheet.
2. A Cost Estimator where you can select the billing unit from a dropdown list, cost per billing unit, heater BTU, and number of hours the heater is run. For the number of hours, you can use either the hours calculated in the Scratch Pad or enter your own figure. The spreadsheet calculates cost by taking the cost per billing unit and dividing it by the number of BTUs in that billing unit to arrive at a cost per BTU. It then takes the cost per BTU and multiplies that by the Gross BTU output of the heater to get the cost per hour to run the heater. The cost per hour is then multiplied by the number of hours the heater is run to arrive at the Total cost to run the heater for X hours.
A couple of other notes:
 1. Spreadsheet was created using Excel 2010 & 2013 (*.xlsx format). I was unable to upload an *.xlsx file format. So, I saved it to the Excel 972003 format (*.xls). As a result, it's possible that some of the fonts/colors may not display properly.
2. Spreadsheet is set up to use with Natural Gas heaters only. It estimates the variable usagebased cost that appears on your bill. Fixed costs that appear on your bill are not factored into cost calculations since, by definition, a fixed cost is static and would appear on your bill as the same amount each month regardless of consumption.
Post to this thread if you have any suggestions or comments on this spreadsheet.
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