About Us


Siddons put the first heat pump water heater onto the Australian market in 1983 known as the Siddons Solar Plus, and created and sold many businesses along the way.

Hydrosol evolved from the previous four decades of research and business around heat pumps. Hydrosol is focused on all-electric, holistic solutions starting with understanding your requirements, providing expert advice and design combined with best products and installers to give you a great outcome.


Siddons Industries (Sidchrome, Ramset, Raypak, Rockwool Insulation) pioneers heat pump technology with the University of Melbourne

Fitzroy Council swimming pool heated by Siddons
heat pump, first commercial heat pump project



Siddons SolarPlus launched as the first domestic heat pump water heater on the Australian market (typical product life span 25-30 years) using solar panel evaporator coil

Research commences on lower cost tank wrap-around heat pump condenser coil



Tank wrap-around heat pump condenser coil international patent granted

Quantum Energy Systems launched upon the new patented condenser coil



Quantum Energy Systems sold

Research commences on improved tank wrap-around heat pump condense coil



Improved tank wrap-around condenser coil created, international patent granted

Siddons Solarstream launched upon the patented Split heat pump water heater



Improved tank wrap-around condenser coil international patent and associated intellectual property sold

Bolt-on Heat Pump launched as a new Split heat pump water heater with simpler water line connections



Siddons Solar Hydronic Heat Pumps launched for radiator and underfloor heating/cooling

Siddons Greenpower launched to install large scale solar farms



Bolt-on Heat Pump business sold

Siddons Solar Hydronics launched integrating the power of the sun (solar) with the use of water (hydronics) to provide your home with the most comfortable form of heating and cooling that costs little to operate and is good for the environment. This involves heat pump hydronic heating/cooling, air conditioning, ventilation, hot water and LED lighting.


Siddons Solarstream (heat pump manufacturing) and Siddons Greenpower (solar power contracting) businesses closed.
Siddons Solar Hydronics (all-electric solar power, heating, cooling, ventilation and water heating solutions) name changed to Hydrosol.


‘’Hydrosol’’ is the new shorter name for Siddons Solar Hydronics encompassing the idea of solar power for heat pump hydronic heating and cooling, providing your home with the most comfortable form of heating and cooling that costs little to operate and is good for the environment.


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The Siddons legacy

The iconic Sidchrome spanner business was founded by the late Royston Siddons prior to WW II to assist in the war effort, well known for its jingle “You Canna Hand A Man A Granda Spanner”. 

Other well-known businesses in the Siddons group included Ramset Fasteners, Welding Industries of Australia, Raypak Heaters, Siddons Insulation (Rockwool) which were divisions of the public company Siddons Ramset Limited, since sold. In the late 1970s, John Siddons, Royston’s son, was a pioneer in the field of sustainability. As a founding member of the Australian Democrats, he lead the first wave of green politics at the federal level in Australia, helping to win causes such as stopping the Franklin River Dam project in Tasmania.

In keeping with the theme of sustainability, Siddons acquired an Adelaide based Rockwool insulation manufacturing company known as Siddons Insulation which was sold in 1984 after winning power station contracts at Loy Yang (Vic) and Tarong (Qld) for boilers and steam pipes. This business was managed by Chris Siddons, John’s son. Chris then moved to the Ramset division and became Managing Director of the Ramset international group in 1990, two months before the major “recession we had to have” hit necessitating significant changes to the Siddons group including the sale of Sidchrome in 1993.

Siddons Heat Pump Water Heaters

In conjunction with the University of Melbourne (Bill Charters), Siddons started work on commercialising the concept of a heat pump water heater in 1975. The first project was the family pool, and then the Fitzroy public pool.

This early pioneering work in heat pump technology progressed to a domestic water heater. 

By 1983, a product was ready for market launch with the ‘Siddons Solar Plus’, released as a ‘solar boosted heat pump water heater’, the first heat pump water heater on the Australian market.

The design was very successful and set a new benchmark for energy savings. The (then) Victorian State Electrical Commission surveyed one hundred users of the product with the response the best they had ever received. 

The Evolution to Solar Hydronics

The Siddons family sold Quantum in 1999 and then started researching improvements for a new heat pump water heater. This led to a new coiled condenser tank and Split heat pump with globally patented design improvements, which in turn led to the formation of Siddons Solarstream in 2005. The technology was eventually sold in 2013.

Siddons Solarstream went on to develop the Bolt-on heat pump water heater, using a simplified method of connecting the separate heat pump to the hot water tank. This business was sold in 2017. Siddons Solarstream also expanded the use of heat pumps for heating and cooling. There were many issues to overcome but Siddons is confident that heat pumps have arrived for cost effective hydronic heating, able to replace the traditional use of gas heating.

In reverse mode, heat pumps can also provide cooling. Hydronic heating and cooling is not only the most comfortable form of climate control but is also the perfect match for renewable energy such as solar power because modern heat pumps only require a small amount of electricity to operate effectively.


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