Determining heat pump size

[No2rdame]

So, looking at adding a heat pump to our pool. I'm in Florida, so it never gets below freezing but it sometimes dips as low as mid-30s once or twice per year. The pool is 8500 gallons in a narrow rectangular shape (7 feet wide at its narrowest), and I've gotten quotes of 4200 and 5000 for a 128kbtu and 135k btu heat pump respectively. The former quote does not include upgrading the breaker switch from a double 20 amp to 50 amp but the latter does and though I could replace the switch myself, I will probably have an electrician do it only because the wiring SHOULD handle 50 amps but not sure how to test that.

1. Is this size heater overkill or reasonable?
2. Is this a reasonable estimate for the cost of a heat pump? I know I didn't mention brands, etc, but just trying to get a ballpark feel.

 

[ajw22]

Most heat pumps shut off below 50 degrees and their output declines as the temperature drops. See the chart below. The bigger the heater the better for heating your water.

Pentair has this

Heat Pump Calculator

See how much you could save by switching to one of our pool heat pumps in just three easy steps. Use our Pool Heat Pump Calculator to see your savings today!

www.pentair.com

Prices seem reasonable.

Heat Pump Performance

• ajw22
• Feb 23, 2019

Pentair Ultratemp Heat Pump BTU Output by OAT

 

[SBall]

Measure the wire, and if it is 8 gauge or thicker, should be ok. Swap the breaker out yourself for $10. Buy the heater off Amazon, spend a couple hundred bucks in miscellaneous plumbing and electrical stuff, and save yourself a few thousand bucks. Seriously, there is nothing difficult about installing a heater. The most difficult part is just tying into the return lines.

 

[sktn77a]

That size heatpump should raise the temperature in your pool by about 1 degree per hour. It should also be enough to maintain the temperature if you use a solar blanket. Residential heatpumps top out around the 120-140kbtu size you're looking at