Quick video how to connect a heat pump to your swim spa hot tub , easy! Balboa - Master Spa

65000 btu heat pump bought for under $2000, tired of my 4kw element heater taking days to heat my water, and hogging power. Savings in electricity.
4kw element heating 1500gal or 4800L by 65deg F or 29 deg C
Takes 4800l x 29C x 4190J/L/degC = 583,248,000 joules / 3,600,000 kj/kwh = 162kwh of electricity (at 11c/kwh = $17.82)
To heat the conventional way. (40 hours at 4kw)

With a heatpump of 65000 btu (ideal conditions 80F air im going to halve that figure, cause it's cold outside 50F)

So we figured it takes 583,248,000 Joules to heat that water above.
So the heat pump consumes 2kw. But at 32000btu its outputting 9671 Watts or Joules per second.
583,248,000 Joules / 9671 = 60,308 seconds = 16.75 hours.

Electrical cost. 2kW consumption x 16.75 hrs = 33kwh = $3.68
If the air temp was 80F /65000 btu it would be half that.
If your initial water is warmer, then obviously that would decrease that too.

Conclusion, heat pumps are a little more noisy, but cut the costs and heating time over the long run.
The downside. If the weather is too cold outside, the heatpump shuts down, in that case, will need to plug in the 4kw heater element again
Ian Roux