Letter to the Editor RE energy-efficient pools
I believe that today clients are always interested in energy efficiency and many are willing and able to pay for the extra upfront costs involved. The hot-topic energy-efficient item today is the variable speed (VS) pump. Pool builders should offer this energy-efficient item of equipment, at least as an alternative, to every client.
Before that will happen, however, the pool builder needs to be convinced of the benefits of the VS pump, because unless they believe in energy efficiency, unless they believe in the benefits of this pump, they will never be able to sell one. Unless they understand how it works and how it is going to benefit the client, they cannot explain or sell it to their customers. They must also be able to build the pool’s hydraulic system to match it. Again, if they can’t do this or explain the benefits of larger pipe sizes they will not try and sell the pump. They will even try and turn the customer away from such items if they ask for them.
So I believe education of the pool builder is vital and must come first. In the meantime, suppliers of such equipment should continue to promote the virtues of their products in all forums — pool shows for the potential customer and in tradeshows and similar forums for the pool builder.
There are some items in and around the pool that are not suited to a VS system, such as fountains, slides, spa jets, etc, but even some of some these can sometimes benefit by a larger VS pump operating at a lower speed to get the desired flow.
Most energy is used by the pool filtration pump and that is where the best savings can be made. I am a convert to the VS pump, but providing customers with this pump without a matching hydraulic installation, without the right characteristics and without proper instructions on its use, can see potential savings rapidly evaporate.
If the VS pump does not have a programmed start-up at full speed, and is on a normal pool that is not being used every day (and there are many of these), the pool will suffer ‘dead’ spots where algae will happily grow. Energy savings may then be used up in removing algae from the pool.
Every pool has its own unique water motion that is set up by the placement of the inlet eyeballs and the skimmer box or other outlets. So, as much as possible, eyeball inlets should be placed to ensure there are no dead spots in the pool. It only takes 10–15 minutes to set the pool water in motion when the pump starts. It then requires much less flow to keep it going and finally it can take up to six hours for it to cease when the pump turns off. Using a programmable VS pump set to run at high speed for that first 10–15 minutes is vital to the pool water quality.
If the suction and return lines are not sized to match the flow of the pump at its highest speed, the pool owner will never get the full efficiency otherwise available to them.
Pump suppliers that sell VS pumps with a capacity that demands 65 mm inlet and outlet connections don’t assist builders or customers by supplying that pump with a 65–50 mm reducing coupling so that a pump apparently capable of 500–600 L/min can be plumbed with 50 mm pipes. I would like to see more pools use 65 mm pipe as it is a very hydraulically suitable size for so many installations where 80 mm can be overkill. Its price would also reduce if it was used more often. A 65–80 mm fitting would be more appropriate due to the difficulty and cost of obtaining 65 mm pipe and fittings in this country.
Using 50 mm pipework on a VS pump of such a capacity as to require a 65 mm connection only guarantees that the client will never get the true efficiency available from selecting this sized pump.
For many years I attended every talk or educational program on hydraulics I could find. They normally lasted 1–1.5 hours and I would come out of every one, just like all the other attendees saying, “What the f*** was that all about?” Even basic hydraulics cannot be learned in such a short time.
Hydraulics is about the movement of liquids in pipework. The current SPASA training on hydraulics (mentioned in your article) spends about 30 minutes on true hydraulics and that is only in the ‘Advanced Hydraulics’ course. No matter how long or often this course is given, there will be no change in the ignorance of pool builders on the subject. I had to do a full three-day Genesis training course in the US before I actually understood what it was all about and to be able to design pool plumbing to match both the pump and the pool’s needs. I have condensed this Genesis course into a full-day session, delivered it around this country, in New Zealand and Singapore and I still get calls from some attendees who struggle with the subject.
It is not easy but it is vitally important to have some usable knowledge of this subject before expecting energy efficiency to take off in this industry. This topic should feature in every Cert IV pool builder course.
Having said all that, I struggle to find the energy efficiency in an in-floor cleaning system. While I wish I had installed such a system in my own pool, these systems are not for every pool. They work well when the debris level is low but can struggle when it is higher. In dryer climates, leaves fall in volumes that many systems cannot keep up with. Many systems installed in lap pools are not designed correctly and it can take days for a particular leaf to reach the extraction outlet, if ever. Too many systems are left with dead spots where debris collects when it shouldn’t.
I have become a convert of the robot cleaner. It can clean most pools spotless in an hour and only needs to be used every few weeks. Is it energy efficient? It certainly saves my energy!
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