Case Study | Specialist

River water powers pool heat

A CUTTING edge project that uses water from the River Trent as an energy source to provide air heating and cooling, water heating and humidity control within an indoor swimming pool has scooped a national award for energy efficiency.


In what is thought to be one of the first projects of its kind in the UK, water from the River Trent is being used as a heat pump energy source to provide optimum water and air temperatures for an indoor swimming pool, a valued amenity for the residents at a luxury apartment development in Nottingham.

Specific to this installation are two Calorex 25kW water source heat pumps that are designed to collect low grade energy stored in the river, which is then upgraded to a useable temperature and transferred (or ‘pumped’) into the building’s heating system at up to 55°C.

It is such an efficient process that it can provide full electric space and water heating at lower running costs than a condensing gas boiler. 

The capture of renewable energy from the river also leads to very large reductions in CO2 emissions compared with any conventional fossil fuel.

Heat pumps operating in this way have proven to reduce running costs by 48% against Oil, 22% against Gas. Carbon savings are just as impressive with 54% against Oil and 37% against Gas being achievable.

In the case of The Crescent Apartments, hot water that the heat pumps generate is fed to a Calorex Delta 12 heat recovery air handling unit, via a buffer tank, which provides space and water heating to the pool and room via LTHW heat exchangers. The Delta 12 is also capable of providing pool hall humidity control and automatic introduction of outside air quantities via a heat pump dehumidifier.


The Delta 12 provides full heat recovery by recycling latent and sensible energy, which has evaporated from the swimming pool, back to the pool water and room air as useable heat. In so doing a complete heat cycle is created that provides some 70% of the facilities energy requirements. During the summer months this feature is reversible so that incoming outside air can be cooled.

A heat pump heat recovery system such as the Delta 12 will cut pool air and water heating requirements by as much as seven times compared to a total loss fresh air system, and perfectly complements the requirements of heat pumps.
Inital data from the site suggests that the complex will operate with power consumption in line with calculated savings that predict a payback against a conventional system in less than three years.

The river water extraction scheme at the Riverside Cresent luxury apartment development, near Nottingham, was designed and installed by swimming pool specialists, Beaver International, in conjuction with British manufactuer’s Calorex Heat Pumps. The project was recently confirmed as the Swimming Pool and Allied Trade Association’s gold winner in the category for best energy efficiency project.

To find out more about its extensive range, contact Calorex Heat Pumps:
01621 856611 or visit