In reading over my prior post, I found the most basic of mistakes - the surface area of my pool is only 112 square feet (8x14).
Thus assuming no wind and R value of cover of 0.5 - to calculate air temp when heater on constantly:
max heat output of my 4 kWh heater in BTUs = surface area x difference in pool and ambient air temperature divided by the R-value
88F - (13600/121*0.5) = 88-60.7 = 27.3F temp when heater turns on constantly...
So, over the last 66 days (mid-Nov thru mid-Jan, Seattle City Light bills are every 2 months...), everything else being equal, the additional cost of my pool heater + pump etc has been ~ $9.68 per day or ~88kWh per day. The average temp per the National Weather Service was 45-46F over that time period.
Since the max energy use from my 4kWh heater in 24 hrs would be 96 kwH per day, it clearly is not on all day. And given the recalculation on when the heater should be on constantly (worse case scenario), it hasn't been cold enough to trigger that event.
I am thinking about experimenting with 3 of the 2 inch thick 4 by 8 foot pink boards with an R value of 10 floated under the cover to see if I can save a cup of coffee per day.....at ~$100 total, even if it only cut my heat loss in half, it would pay for itself in just under 3 weeks.
Thus assuming no wind and R value of cover of 0.5 - to calculate air temp when heater on constantly:
max heat output of my 4 kWh heater in BTUs = surface area x difference in pool and ambient air temperature divided by the R-value
88F - (13600/121*0.5) = 88-60.7 = 27.3F temp when heater turns on constantly...
So, over the last 66 days (mid-Nov thru mid-Jan, Seattle City Light bills are every 2 months...), everything else being equal, the additional cost of my pool heater + pump etc has been ~ $9.68 per day or ~88kWh per day. The average temp per the National Weather Service was 45-46F over that time period.
Since the max energy use from my 4kWh heater in 24 hrs would be 96 kwH per day, it clearly is not on all day. And given the recalculation on when the heater should be on constantly (worse case scenario), it hasn't been cold enough to trigger that event.
I am thinking about experimenting with 3 of the 2 inch thick 4 by 8 foot pink boards with an R value of 10 floated under the cover to see if I can save a cup of coffee per day.....at ~$100 total, even if it only cut my heat loss in half, it would pay for itself in just under 3 weeks.