The Swimming Pool & Spa Association of Queensland Inc (SPASA) shares some tips and advice on installing solar pool heating and the benefits it provides.
Installing solar pool heating can increase the use of your pool by up to four months. By using the heating energy from the sun, the cost to heat a pool in this way is very economical. While the type of solar system may vary, the basic principle remains the same. Pool water is circulated through a series of tubes (the collector), usually mounted on the roof, where heat is absorbed and the heated water returned to the pool.
There are two types of collectors currently available: the first is an open style of collector and the second is an enclosed style. The open-style collector is traditionally made of either EPDM Rubber or PVC/TPR material and is usually supplied in multiple tube “strips”. The enclosed style of collector is traditionally made from HDPE plastic and is encapsulated inside an aluminium-framed box.
The amount of heat absorbed and the ultimate increase in pool water temperature depends on several factors that should be considered when deciding on a solar heating system for your pool.
They are:
- Size or area of collector, number of tubes per square metre or number of enclosed panels
- Location or positioning of collector
- Control system
Size or area
The amount of collector used in your solar system will have a major influence on the effectiveness of the system. The size of the collector is usually expressed in square metres or number of panels and, as a general rule, directly relates to the surface area of the pool.
For open-style systems, Australian Standard 3634 suggests a minimum collector area equal to 60 per cent of the surface area of the pool, only in ideal conditions, whereas closed-style systems require about 30 per cent of the surface area of the pool.
The area of collector generally needs to be increased depending on variables such as local climate, shading of roof or pool, slope and orientation of roof, wind protection, type and colour of roof and collector type.
Larger systems will be needed where higher-than-average water temperature or extended swimming season is desired.
In accordance with the above, SPASA recommends a minimum area of 80 per cent for most installations for open-style systems and a minimum area of 30 per cent for closed-style systems.
Location and orientation
Collectors (other than those on flat roofs) should ideally be placed on north-facing roofs. Deviation is allowable as long as collector area is increased accordingly. Collectors should be located to avoid shade from objects such as trees, neighbouring houses etc for at least six hours every day.
Remember, the following will all affect the size and location of your solar system:
- Pool surface area
- Roof orientation
- Shade on collector or roof
- Colour of roof and pool
Pool pumping requirements
To circulate water through the solar system you can either use the existing pump or provide a dedicated pump (a dedicated pump is required for a closed-style system).
If the existing pump is to be used it must meet the following conditions:
a. The required rate of turnover of the pool water for filtration purposes shall be maintained.
b. The operating pressure of the filter shall not be increased above the manufacturer’s maximum pressure by the addition of the solar circuit.
c. The pump shall have sufficient capacity to handle the static head and friction losses introduced by the addition of the collector circuit.
d.The average domestic solar installation requires a minimum flow rate of around 100–200 litres per minute to operate effectively. In most circumstances, this would mean a dedicated solar pump would be required.
e. Always check that the minimum design flow rate of the collector is met when selecting your pump. This flow rate will vary with the diameter of the tubing used.
f. The circulated water needs to be strained to avoid blocking up the collector with dirt and debris, so when using a dedicated pump, some form of strainer must be provided.
Important points:
- Make sure pool filtration requirements are met
- Ensure correct flow rates are obtained
- Circulated water should be strained
Solar controllers
As nobody can guarantee the time of the day the sun will actually shine, time clocks are of little use in controlling solar heating systems. What is needed is a temperature-sensing control device. These units will operate the solar pump system only when heat can be gained. This ensures that maximum heat gain is obtained.
Circulating water through a cold collector will cool the pool at a faster rate than it can be heated.
Handover and documentation
At the time of handover, the pool owner should be provided with an appropriate document certifying that the system has been installed and commissioned satisfactorily. The owner should receive documentation covering:
a. A list of all major components, including the size and make of solar collector, make and model of the control system, components and pump.
b. Copies of all warranties as issued by the manufacturers of the components and any warranties issued by the installer should also be provided.
c. Operating, preventative maintenance and service instructions describing start-up, normal running and shut-down procedures in an easily understood form.
d. A record of the date of the installation and the name and address of the contracting installer.
Each company differs in the products they offer, so it’s worth doing the research to find out what best suits your needs. The Solartherm Solar Pool Heating Panel is fully enclosed inside an aluminium-framed box. It looks similar to a domestic hot water panel. Because of the improved efficiency of the Solartherm panel, it requires a lot less roof space than the traditional open solar matting systems available.
In most instances, traditional solar matting collectors require 60–100 per cent coverage of your pool’s surface area (ie, if your pool has a surface area of 32sqm, you would traditionally require up to 32sqm of matting on your roof).
Because of its improved efficiency, the Solartherm system requires only four of its panels to provide the same results (subject to orientation). It can be retrofitted to your existing pool whether it is plumbed for solar heating or not. As it is a fully enclosed system, it has the added benefit of being resistant to damage caused by various birds and wildlife, as well as hail and storm damage.
Another alternative is a Heliocol Solar Heating System, with patented Individual Tube Design™ technology. Heliocol solar pool heating collectors are unique in that all the individual risers are fully moulded into the header and footer tubes during manufacture. This eliminates the need for hundreds of on-site connections, reducing the chance of future leakages from these points.
Perhaps the greatest feature of Heliocol is the quantity of tubing able to be installed in a given area. Due to the over-moulding process used in the manufacture of the product, the individual tubes are extremely close together. This allows Heliocol to provide 137m of tubing per square metre of surface area.
The Heatseeker Maxi Evacuated Tube system by Supreme Heating is ideal for indoor, lap pool and spa applications where higher temperatures and year-round heating input is required. This is a high-performance system designed to make hot water. The system can be mounted on frames, which makes it ideal for any roof, and only needs 40 per cent of the area of a traditional strip system to duplicate performance.
The key component of this system is the evacuated tube that consists of two glass tubes. The outer tube is made of extremely strong transparent glass, which is able to resist hail up to 25mm in diameter. The inner tube is also made from borosilicate glass but is coated with a special selective coating developed at the University of Sydney that provides excellent solar absorption and minimal heat reflection. This makes it ideal for use on colder, cloudier days in winter.
Sunbather has always been driven by a search for better ideas to provide every pool owner with greater choice. Sunbather’s Flat Loop Technology now offers pool owners a choice between “fat” loops and “flat” loops. Every FLT collector strip lies completely flat against the roof. It’s a world first and was recognised for its ingenuity and complexity with the 2004 Product Innovation Award.
And in 2005, Sunbather announced yet another innovation. Kwik-Lok is a sophisticated connection system that results in a quick, neat and clean installation. It also makes it easier for those who have not installed Sunbather before to achieve the Sunbather quality standards.
Solar is a long-term investment, so make sure you do your homework and find the best solution for your pool.
DETAILS
The Swimming Pool & Spa Association of Queensland Inc (SPASA) is a non-profit trade association dedicated to maintaining and improving standards within the industry for the benefit of consumers, pool builders and suppliers. There are many issues and problems affecting the industry and consumers that are either impossible or too great for any one business or person to handle effectively. This is why the industry itself has formed a mutually beneficial, co-operative and non-profit trade association.
For more information visit www.spasa.com.au