Design philosophy
Unglazed collectors are permanently filled with pool water during the summer season and are drained when not in use. When solar energy is available and of useful grade—as determined by comparing the temperature of a roof-mounted sensor with the pool’s return water sensor, using a dedicated controller—a solar pump is enabled, drawing a fraction of the pool’s main pumping volume and diverting it through the roof-mounted collectors. This water mixes with the main pool feed on return and the existing boiler/heat exchange system is used to bring its temperature up to the required set point. As such, this is considered a supplemental source of heating. An EnerPool simulation software helped determine the system was capable of delivering approximately 47,000 equivalent kilowatt hours (ekWh) of energy per year.
Implementing the design
After being tendered to pre-selected bidders, the system was finally awarded to Solcan Ltd., in London, Ont., a specialist, design-build contractor with experience in solar thermal technology for indoor and outdoor pools.
The implementation of the solar water heating system took nearly a month. The city installed a separate control system—that monitors the solar equipment—to measure the device’s performance. The main features of the heating system are:
- A flow meter, which measures the flow of water through the solar loop and records it on a local screen.
- The supply/return temperature sensors. The multiplying flow of water and its temperature variance across the solar supply/return loop results in a calculation of energy generated by the solar loop, which is used to calculate the system’s performance.
