Print full article

A look into the effectiveness of below-ground solar heating systems

What happens when the pool gets too hot?

project-complete_e
A below-ground solar heater (i.e. hydronic system) circulates fluid through panels located under the paver surface and, as it heats up, it passes through a heat exchanger, which transfers it to the pool or hot tub water.

If the pool reaches the target temperature, fluid will stop circulating through the panels. This prevents the system from continuing to heat the pool; however, it will also stop cooling down the patio/deck surface. Therefore, in cases where patio cooling is necessary, the system can have an alternative location to dump the heat energy, like a pond or domestic water heater. This allows the system to continue drawing heat energy from the patio/deck to cool it down even when the pool does not need to be heated.

If the project is such that there is no alternative means for the excess thermal energy heat, a chiller can be installed to cool and compensate for the surplus heat energy. This is, of course, only necessary when patio cooling is required. It should also be noted, when designing a system, all of these scenarios can be mapped out based on the climate of the pool location, pool size, patio/deck surface material, paver colour, target pool and patio temperature, amongst other attributes. This type of mathematical planning allows designers/builders to determine if 
a particular location would benefit from having a chiller, a pool heater, or if the location could possibly run into problems with excess or deficient thermal energy. This analysis can also determine the return on investment (ROI) for a particular project.

What if there is not enough thermal energy for pool heating?

When there is not enough thermal energy to heat a pool to the target temperature at any specific time, a pool heater can make up the difference. Even when this is necessary, a below-ground solar system can potentially reduce pool heating costs enough to elicit a rapid ROI. Every type of pool heating system has different operating costs with the most expensive often being electric. Replacing an electric pool heater with a hydronic system will give the homeowner 
the fastest ROI, while a slightly slower ROI will be observed when using a gas heater.

How is it installed?

The below-ground solar heater manufacturer provides on-site training for the contractor to ensure a proper and efficient installation. Most of the time, the plumber or mechanical contractor will be in charge of installing the system, so piping, manifolds, pressures, and heat loads are of minor concern to the hardscaper. These systems are also pre-designed by the manufacturer with specified pumps, pressures and layouts, making the install seamless, as it is well thought out and planned ahead. Any concerns with equipment compatibility will be addressed by the manufacturer, therefore, leaving nothing in question. The installer (i.e. mechanical contractor, plumber, etc.) will also work closely with the landscaper to ensure the entire process is co-ordinated.

Estimated return on investment (ROI) analysis for a typical pool owner
If a standard-size pool, equipped with a propane heater, was installed with a below-ground solar heating system, the operating time of the fossil fuel heater could be reduced by 75 per cent to maintain a constant water temperature of 30 C (86 F).

When factoring in the cost of propane and assuming weather conditions were steady each month, and a pool cover was used 10 hours a day, the return on investment (ROI) for the below-ground solar heating system would be approximately six years.

Further, patio surface temperatures can reach upwards of 74 C (165 F) in the summer (depending on the region), which is third-degree burn territory. The below-ground solar panels can lower the surface temperature to 32 to 43 C (90 to 110 F) to create a cool and comfortable patio, while at the same time providing supplemental heat for the pool.

Leave a Comment

Comments