Hal3
The program is optimistic; however, not overly optimistic.
The program calculates the costs for the heat pump based on the FULL rated output using 80 f for the entire heating cycle.
In order to factor in for the reduced output at lower temperatures, calculate the number of hours per month when temps are in the 60s. Then multiply that hourly operational cost by 1.25. This should give you a fairly accurate monthly cost for these units and other brands of comparable size.
The 1.25 Winter adjustment factor can be found on page 22 of the Autopilot heat pump guide.
http://www.aquacal.com/images/stories/p ... manual.pdf
Entering the specifications for my pool and using a comparable output/input autopilot product yields monthly rates comparable to the actual costs that I pay during the warmer part of the season. Applying the 1.25 adjustment factor for the first and last month of operation yields accurate monthly rates during the beginning and end of the swim season.
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To get the most accurate information, you need to input the total energy costs.
Base electricity rates in my area are 8.8 cents/kwh
After the environmental compliance fee, nuclear construction cost recovery fee, municipal franchise fee and sales tax are added to the bill, I then divide by the total number of kw used to calculate a cost of 10 cents/kwh.
I enter 0.10 into the Electric kw rate on the AquaCal program.
Calculate the total natural gas cost per therm in the same manner. Your total bill divided by the total therms used.
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The program default is to heat to 80 F, but you can override the temperature difference. If you wanted to calculate for heating to 85 f then add 5 degrees to the temperature difference value.
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A very useful and educational program.
Thank you for posting the link