In the rural areas of Australia there are a few choices of energy source available such as solar, wind, diesel, LPG and waste oil.
Solar is great for small domestic (potable) hot water, however, if you would like to reliably and quickly heat a domestic swimming pool of e.g. 60,000 litres from 15 C to 25 C within a day or two (and keep it at 25 C) you really need some serious power to make it practical.
This tends to leave the energy choices to either diesel, LPG or waste oil, especially in rural areas where natural gas is unavailable out of town or on the farm.
If you do an approximate cost analysis, diesel is around $1.20 a litre, LPG is around $0.60 a litre with waste oil typically $0.20 a litre. Waste oil prices tend to remain the same, whereas diesel and LPG fluctuate depending on international trading circumstances.
LPG looks good so far, however, it is heating value (Mj rating) is 22 Mj per litre, whereas waste oil has around 38 Mj per litre. So, practically then, you need nearly twice as much LPG to generate the same amount of heat.
Diesel and waste oil are normally around the same heating value. A 50 kW waste oil compatible water heater will typically heat the home, swimming pool, spa and domestic hot water with fuel cost at $0.20 per litre.
Shire council pools in rural areas are not usually heated at all. These pools therefore are virtually unusable in winter. It seems strange to have an expensive public asset lying dormant for big chunks of the year.
Consider all year use of the pool; you require warm water. Often a business case for heating installation costs can be rationalised when these costs are offset against extra income from all-year usage and low ongoing energy bills.
Therefore, some rural councils are heating their pools on waste oil to produce a year round asset and public service. The swimming pool at left is heated on waste oil with Kroll. Air temperature around 10º C midday and the location is a rural pool 150 km south east of Melbourne, Victoria.
The waste oil burners are available from Kroll Heaters.