Sustainable Heat Technologies

With energy prices and environmental impact being causes for concern for many consumers, they have become more conscious of issues surrounding the cost of running electrical equipment and the carbon footprint they are responsible for. Hot tubs are pieces of electrical equipment, fitted with electric heaters which, normally, are heated using regular mains electricity. There are two principal technologies to consider as alternatives which can reduce your energy bills as well as reduce CO2 emissions and they are outlined below. You will also have to consider the amount of space required for the heaters and the fuel.

Solar PV

Your home can be fitted with solar photovoltaic panels (PV) which are fixed to a south facing surface such as a roof, or, on special metal frames on the ground. They generate electricity from the sun’s rays by converting light energy to electric energy. You will generate a lot more power on a long clear sunny day than you will on a short cloudy day and the more panels you install, the more electricity you will generate. The electricity generated is not used by the household itself, but flows back into the grid. The government wants to promote the use of green technologies and encourage home owners to install renewable systems; therefore the home owner is paid what’s known as a ‘feed in tariff’. The amount returned is, generally, significantly higher per unit than the cost of buying electricity in. This means that if you install a large enough area of panels, you can completely offset the carbon produced from your hot tub usage, including the running costs. Please visit for further information and the conditions that apply.

Solar hot water

When heating hot tub water, the period of most energy demand is immediately after filling the spa from empty. The water needs to be heated, through the hot tub’s built in heater, from cold up to the required temperature (36 – 40° Centigrade). However, it is possible to achieve this by filling or part filling the hot tub using water heated by either solar hot water evacuated tubes or flat panel collectors. These work by using the sun’s energy to generate heat, by trapping the sun’s energy in highly efficient glass tubes or panels. In these systems, small amounts of fluid are converted to superheated steam (often over 200ºC on very clear sunny days) and the heat transferred to a heat exchanger, which is then used to heat the hot water.

The hot tub’s in-built electric heater would then only be required to be active for much shorter times to maintain the set temperature during normal use, which uses much less energy. It is not generally possible to replace the hot tub’s heater completely with a solar hot water feed, as it would not operate at night and may not respond quickly enough at other periods. It would also require some major modifications to the spa’s interior plumbing which would void most hot tub manufacturer’s warranties.

Biomass hot water

This is again a method of obtaining hot water for a fresh-fill of an emptied hot tub, derived from a renewable source, rather than by electricity, to heat the hot tub water to working temperature from cold. Here, water is heated from a specialist heater which is designed, as the name implies, to burn organic fuels taken from a sustainable source. Such heaters are built to burn logs, wood pellets or wood chips, which are fed automatically into the combustion chamber from an adjacent store.

As with solar hot water, heated water from a biomass source would help raise the fill water to near desired temperature, and the hot tub’s in-built electric heater would, again, then only be required to be active for much shorter time periods to maintain the set temperature during normal use, which uses much less energy. It is not generally possible to replace the hot tub’s heater completely with a biomass hot water feed, as it would also require some major modifications to the hot tub’s interior plumbing, which would void most manufacturers’ warranties. Now that you have a little bit more information, the choice about whether to harness these forms of sustainable heat technologies is up to you!

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