If you have chosen the heat pump option, gaining an understanding of how a heat pump is rated is vital to you selecting the correct capacity to meet your needs.
The Australian market now offers a myriad of brands. Indeed, new entrants move in and out of the market with ease as there are very little regulatory restrictions or requirements to be met before the sale of an imported unit can commence. There are no Star-Ratings or similar requirements to aid you.
The variance in the rating (expressed as the KW output) of heat pumps with identical compressor capacity can be dramatic. This leads to very distorted price comparisons and the potential for the under-sized units to be purchased.
The output of a heat pump can vary by as much as 100% depending on the ambient temperature at which it is operating. The output is reduced at low ambients and increases substantially as more heat transfer becomes available at warmer temperatures.
The critical aspect becomes at what ambient temperature does the heat pump achieve its "marketed" or rated KW output.
Typically, imported heat pumps provide ratings at high ambient (27°C) while Australian manufacturers follow local air-conditioning codes and provide a rating at 15°C (dry bulb)/12°C (wet bulb), with an pool water temperature of 27°C.
The critical aspects for the potential heat pump purchaser are firstly, finding a common rating point so that an apples-for-apples comparision can be made of output (and thereby, price) and secondly, determining if this this capacity is adequate to meet the expected heat loss from their pool during the coldest weather they are likely to face.
The onus is on the purchaser to be satisfied with the capacity and efficiency of the heat pump and with the ongoing reliability of the supplier to provide technical and service support including spare parts through the life of the equipment.