Heat Pumps

- are by far the most cost-effective way to heat a poolCalorex Heat Pump

The technology has been around for decades and is basically the same refrigeration circuit that you'll find in a domestic 'fridge or freezer, an air-conditioner, water cooler or dehumidifier

For every unit of electricity you pay for the heat-pump puts the equivalent of 5-6 units of heat to the pool via a heat-exchanger

It works like this: -

  • An electrically operated fan draws outside air, from around the heat-pump, and passes it over an evaporator coil that is very similar in principle to a car radiator
  • Refrigerant liquid within the evaporator coil absorbs ambient heat from the air and warms up
  • This turns the refrigerant into a gas
  • The refrigerant gas is passed to a compressor
  • As the gas is squeezed down by the compressor its temperature rises; it gets very hot
  • The hot gas now passes into a heat-exchanger where circulating pool water takes up the available heat
  • The gas is passed through an expansion valve and cools rapidly
  • The refrigerant gas now condenses into a liquid state again
  • The liquid passes into the evaporator coil and the process repeats over and over
  • The only cost is the electricity to operate the fan, pump and compressor

Lets imagine a cost of $1 for a given period of time (exactly how long that period of time is depends on the price of electricity from your particular electricity supplier)

Astral Pool Viron Heat PumpIn that period of time the heat-pump will capture anything up to $5 worth of heat from the air and transfer it to your pool-water. One could say that the heat-pump was 'up to 500% efficient'

This gives a Coefficiency-of-Performance (COP) figure of 5.0 whereas the best efficiency you can hope for with an oil-fired heater, a gas-fired heater or an electrical heater is something under 100%, or a COP of less than 1.0

It sounds like something for nothing but really it's not; it's just making good use of an enormous, absolutely free resource - the ambient heat in the air all around us

Heat-pump pros and cons

A heat-pump is the most economic way to heat a pool by far, giving up to 600% efficiency, but are not ideal in really cold climates

In really warm climates, however, they are ideal as they are capable of cooling a pool, also

(When I lived in Arabia the pool frequently reached temperatures of over 40°C in summer and provided no cooling refreshment at all)

Heat-pump pros: -

  • They are the least costly of all pool heaters to operate
  • Eco-friendly; with zero local emissions
  • No deliveries of gas or heating oil required, ever
  • Can operate in temperatures as low as 5-7°C (41-45°F)
  • Can be used to cool a pool when the water gets too warm
  • The exhaust fan can be used to keep your beer cool!

Heat-pump cons: -

  • Initially more expensive to buy
  • Not ideal for colder climates
  • Get noisier as they get older


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Ken Walker - MyPoolGuru©