"Eye144" wrote in message
m...
With electric rates near 12c/kwh(peco philly), My question is how
much it costs to heat up the spa from 70 degrees F to 95' 500 gals


Part 2 would be what does it cost to run the circulating pump system.
It usually gets run 1 hour and it totals 11.5 hp. I've been
thinking about this for a while.
Thanks M

Second try but you are still wrong.

If the pump is totaling 11.5 hp, that is over 36 amps of power at 240 volts.
About 8600 watts at .12 per kW it will cost over a buck an hour to run.

A Btu is the energy that it takes to raise the temperature of 1 pound of
water 1 degree. You need to know the correct weight of the water (have you
found that out yet? it was wrong yesterday) and the number of watts of
energy that is equal to. All this information is easily found. If you have
a program like Convert it is much easier to work with.
http://joshmadison.net/software/

Other factors to consider. Where is the heat loss from the spa going? If
it is in the heated house, it is not lost, just distributed to ease the load
of the home heater. Are you maintaining the temperature for a length of
time? Where is the 70 degree water coming from? This time of year incoming
water is much colder.