By Connie Sue Centrella
The demand for more energy-efficient pools and spas has pushed industry professionals to examine alternative heating technologies. Over the past several years, heater manufacturers have taken new strides to improve efficiency. This is in part due to a shift in government guidelines, whereby building codes are now demanding a rise in ratings to improve the overall energy efficiency of all pool equipment.
In midst of this ‘greening of the pool industry’ there has been increased interest in using geothermal and solar technologies. Heat is naturally abundant from the sun as well as within the earth. Innovative heating technologies have found a way to capture and redirect this heat to warm swimming pool water. These renewable energy technologies are capable of providing a cleaner, greener environment, assuring a more sustainable future.
Historically, heat pumps were considered mainly for warmer climates; however, in the last decade, one of the fastest growing regions to use this heating technology has been in the cooler, northern climates. This is because the heat pump industry has developed highly efficient heating systems, which can operate at lower temperatures. Clean energy occurs within the heat pump technology.
Three heat pump options
Air-source heat pumps do not actually burn energy to create heat; they only use energy to transfer heat from the outside air to the pool water.
A hybrid method is a water-source heat pump. These geothermal heat pumps extract heat energy from the ground through wells, earth loops, surface water, and even from cooling towers.
Heat exchanger technology transfers the heat from the ground source to the pool water. Numerous applications throughout North America have proven this technology to be the future of pool heating. While the upfront expense may seem out of reach for standard pool heating, data shows the payback is within range and acceptable to most pool owners, especially those who are dedicated to greener living.
In many cases, for example, the pool heating system can be partnered with the home’s heating, ventilation, and air conditioning (HVAC) system to increase overall efficiency. During the summer months, the geothermal application transfers the heat from ground loops, cools the home, and captures the exhausted heat to warm the pool water.
An example can be found at the historic Fontainebleau Hotel in Miami Beach, where engineers retrofitted the hotel’s cooling system to incorporate the pool’s heat pump unit with the air-conditioning cooling towers. Some may perceive that geothermal is only from water within the ground; however, this installation example and others prove the versatility of geothermal heat pump systems.
While warmer regions play an important role in the viability of geothermal heating, Andrew Chiasson of P.E. Geo-Heat Center, presented a case study in 2004 stressing that cooler climates require additional ground loops because the air extracts heat from the earth; however, in warmer climates, the economic feasibility of payback is approximately five years.
The four types of source water commonly available to this new technology are open loop, closed/group loops, surface water, and HVAC loops.
The majority of water source heat pumps utilize the open-loop system. This requires two wells, one to supply warm water to the heater and the other to return the water to the extraction depth in the ground.
This technology is highly specialized and only professionals familiar with this type of engineering should install these systems. It is also strongly recommended that local codes be checked to ensure the return water does not interfere with any underground springs.
The closed-loop system uses heat from the ground; however, different from an open-loop system, the heat is absorbed into tubing, which is filled with a mixture of water and ethylene glycol. The heat energy is then brought to the heat pump to be used as the heat supply source.