Author: Catherine Saunders

With energy and cost savings on offer, Patrick Thorpe takes a closer look at variable speed pumps and uncovers the benefits behind their use.

When asked about variable speed pumps, I often start by saying I think the name is misleading! It gives the impression that the speed is constantly changing day in and day out. We all know we need a constant flow so what is the point?

I prefer to refer to them as speed adjustable pumps. Most Variable Speed pumps have three settings each capable of being adjusted to an exact speed. For the moment let’s concentrate on using just one of the three. By being able to set one speed to the exact flow rate set by the pool designer, we end up with a perfectly balanced pool, then as almost a by-product, we have all the advantages of the pump affinity laws.

Let me give you an example: let’s say you are building a 10m x 5m x 1.4m (average depth) domestic pool (70m3), and you would like to have a turnover rate of 6 hours, then you are looking for a pump capable of producing 12m³/h.

You look in your supplier price list and find a 1½ hp pump at a 10m head is not quite powerful enough, so you have to select a ¾hp. That in itself creates another issue, instead of being able to use a 600mm filter you are forced to go for a 750mm.

OK now let’s consider using a 1hp Variable Speed pump. The first saving is we can stick with using a 600mm filter, as it will comfortably deal with the 12m³/h required.

The concept of Variable Speed is as simple as one, two, three:

ONE:  Any change in speed directly changes the flow at the same rates, i.e. 50% of the speed = 50% of the flow. Changes in flow rate are to the power of ONE.

TWO:  Any change in speed changes the head in the system to the power of TWO.  i.e. 50% of speed = 10m head x 0.5 x 0.5 so the head changes to 2.5m.

THREE:  Any change in speed changes the power used to the power of THREE.  i.e. 50% speed = electricity used x 0.5 x 0.5 x 0.5 therefore 1kW becomes 125kW

Now let’s go back to our example of a typical ¾hp pump that uses about 820 watts. We are running a heat pump and want to run the pool say 10 hours a day:

3/4hp pump 820W x 10 = 8.2kW.  Say 180 days x 8.2kW = 1476kW.  At 12p kW/h = £177.12

1hp Variable Speed pump 1,050 watts at 2,850 rpm producing 17m³/h. Flow required = 12m³/h.   Speed required (Power 1) 12/17 x 2,850 = 2,012 rpm (this will depend on the actual hydraulic efficiency of the system, but the calculation should give an excellent indicator of the saving). 12/17 = 70% of the speed. Power used = 1,050 x 0.7 x 0.7 x 0.7 = 360W. Pump 360W x 10 hours = 3.6kW. Say 180 days x 3.6kW = 648kW. At 12p kW/h = £77.76

So where are we? We are using a pump producing exactly the flow rate set by the pool designer working at a power consumption commensurate with that flow rate and at the same time, no dead area issues, no flow rate issues, yet still saving £100 per year. Not forgetting a saving on buying the smaller filter of at least £350 at retail, which means, you will be well on the way to covering the extra cost of buying the variable speed pump. No compromise, just perfection.

Obviously greater savings can be made by running a much lower speed for part of the day, as long as you ensure you have sufficient flow to operative such items as the heat pump and dosing, etc., not to mention numerous other benefits like medium rate filtration.

Go on give them a try!

This article was written by PATRICK THORPE, and first published in the December 2016 edition of Swimming Pool News.  Patrick is former Managing Director of AstralPool UK Ltd, former Chairman of Certikin International Ltd and a key member of SPATA’s Technical Committee.

1   UV light is effective against all micro-organisms

Water purification by UV-C light is the most effective sanitising method available today. UV light destroys micro-organisms in domestic pools up to 99.9%.

2   UV pool sanitisers contribute to crystal clear water

The most important culprit of cloudy water, micro-organisms such as algae, will be eliminated by UV pool sanitisers. But also chloramines can be the indirect cause of cloudy water, especially when the disinfection level of free chlorine in the water is too low. UV-C lamps destroy micro-organisms up to 99.9% and breaks down chloramines up to 80%.

3    With UV purifiers, you reduce the use of chemicals for water treatment

UV-C purification makes sure there is more stability in pools and spas, therefore adding extra chemicals can be prevented.  It is always necessary to maintain a residual of chlorine in the pool water though that level can be reduced through the use of UV.

4   You will have lower costs in chemicals, energy and maintenance

Materials in and around the pool suffer from chemicals added to the pool water. Because UV-C radiation destroys most of the harmful chloramines in the water, the materials in and around the pool get affected much less.

5   There is no risk of overdosing with UV pool sanitisers

Overdosing chemicals in pools and spas can cause serious health problems and even foamy or cloudy water. UV radiation cannot be overdosed and destroys all of the micro-organisms.

6   UV is a green, non-hazardous technology

Last but not least – UV light is an environmentally friendly way to sanitise pool water.

For further information read The Role of Chlorine in a World of UV by Blue Lagoon

Blue Lagoon UV is available in a wide variety of models to suit different pool types, sizes and budgets.

The opening of the new Dartmouth Indoor Swimming Pool next month comes after many years of hard fund raising by the local community. For installers, Westcountry Leisure the new OC-1 filtration system, with its promise of reduced energy consumption and much-increased efficiency,  was a natural choice.

Speaking at the “topping out” stage of the new Dartmouth Indoor Pool in early March, the Mayor of Dartmouth spoke of the enthusiasm within the community as they have watched the pool taking shape.  “There are people here who have contributed to the swimming pool fund over the last 50 years. For a coastal town, it is essential that people learn to swim and feel safe and confident, both working and taking part in activities on the river. Dartmouth town is proud to be part of this development.”

Devonshire pool specialists, Westcountry Leisure installed the beautiful 25m swimming pool using Certikin supplied equipment and, impressed with the claims of the new ground-breaking OC-1 filter media,  felt that this would be an excellent occasion to put it through its paces.

Embracing the recent advances in pump technology and maximising the benefits of variable speed pumps, the ingenious OC-1 works through settlement, as opposed to the traditional method of entrapment. By replacing commonly used media (such as sand and glass) with OC-1 Filtration Media it is possible to reduce the head loss in the filtration system; filter with a constant flow (regardless of debris entrapment) and, most remarkably, significantly reduce energy costs as it can be used with a smaller pump or a variable speed pump or controller. All this whilst still filtering to the equivalent standard for traditional filter media.

Certikin’s Commercial Manager, Steve Nelson, went into consultation with Westcountry’s Mark Gilpin and estimated that using OC-1 compared to sand would in terms of electricity consumption save 71.73kW per day, which over the year equates to 26,181.45 kW.  Assuming a price of 12p a kW, this amounts to a massive saving of £3,141.77 each year!

Mark Gilpin says: “Of course the system has still to be fully tested when the pool opens to the public but thus far I have to say I am hugely impressed. OC-1 has reduced the pump current and running costs dramatically. To be honest, I am amazed at just how efficiently it does work and the results it achieves.  I think it justifies the title of a revolutionary product.”

Add a family of children and a handful of pets to a brand new swimming pool and what’s the essential ingredient?  It is, of course, the Coverstar – the market leading automatic safety cover that is as stylish as it is safe.

Equally stunning by night and day, this beautiful new pool was designed and constructed by Cambridgeshire pool company Aqualeaf Ltd. Bought for the enjoyment of their growing family, the Petersons were keen to maximise safety and were immediately impressed with the robust nature of the Coverstar safety cover.

The Coverstar prides itself on being simple to operate via a key switch and when not in use, the key can be removed, preventing unauthorised operation and adding to the product’s safety.

Mr Peterson says: “What we like about the Coverstar is that it is so easy to use – being automatic, it takes literally a couple of minutes at the most to uncover the pool. We didn’t want a cover that would take ages to put on and off. Let’s face it, in this country in the time that it takes to get some covers off a pool, the weather can have changed!”

Music to the ears of all pool owners looking to reduce their heating, Mr Peterson adds that the cover also scores ten out of ten for retaining the pool’s heat. “In fact, on really hot days we have to remove the cover to let some of the heat out otherwise the water can become too hot for swimming!”

Covered in glory

The Coverstar system is based on strength. For example, the sliders, which are traditionally the weakest part of a cover system, are more than four times as strong as any other slider used in the industry.

The cover’s strength also comes from the heavy duty fabric – the Ultragard 3 vinyl composite fabric is of industrial strength; is available in a variety of colours and offers unparalleled resistance to sun, chlorine and other pool chemicals.

The cover features an exclusive heavy-duty double row of stainless steel ball bearing pulleys which have almost triple the load bearing capacity of single row pulleys used by other companies.

Coverstar will fulfil almost any customer requirement. The shape of the pool is virtually irrelevant as Coverstar’s powerful hydraulic drive and versatile track options can enclose almost any pool.

A team of fully trained engineers is available to install the Coverstar system. Alternatively, written instructions are provided if you wish to complete your own installation.

The brief was simple: a large, luxurious in ground tiled pool that is cost effective to operate. Executing it was not quite so simple but as the pictures reveal, Hampshire pool dealer, Neptune Swimming Pools, with a little help from Certikin, achieved a fantastic result and a very satisfied customer!  Neptune’s MD, Lee Campbell takes up the story…

“After receiving an email from a local building company, who we’d worked with in the past, an appointment was arranged to meet on site as it became clear that this wasn’t just another back yard liner pool install. The client’s request was simple but exacting – a large in ground fully tiled pool which was both luxurious and cost effective to operate.

“All was going well until we discovered that the site was on the very edge of the salt marshes and had a tidal water table, covering the area upon which the pool was to be sited. A specialist ground works team was engaged to provide constant dewatering for what seemed like a lifetime until the external walls of the basement and building were constructed and cured.

“The walls of the pool were then shuttered and cast in reinforced concrete.

Standard white Certikin shell fittings were installed into the shuttering prior to the concrete pour. Flexi pipe work was run around the pool to the basement plant room. Certikin’s white LED lights were installed to compliment the pool hall’s other LED light systems.

“It was clear from the start that we would need a substantial environmental control system so the H&V team at Certikin were consulted and they suggested a Delta 6. The unit arrived on site and was duly craned into the plant room, where it sat for several months as bad weather prevented any progress on site.

“The client had chosen his own mosaic tiles and the pool was rendered out with internal steps at both ends and a bench constructed the entire length of the 15m x 5.5m pool. The pool depth was chosen at 1.40m with a flat bottom profile, so it could be used by all of the family and guests.

“An Aquaspeed pump and Vision filter with glass media were an obvious choice as we have used this equipment for several years with excellent results.

“After careful consideration, a Coverstar safety cover was commissioned with an in wall track system, housed in a pit at the back of one end, covered with heavy duty lid trays and extended brackets so the floor tiles could continue across the cover pit. The Certikin engineers were even able to reverse the boom, so it was set lower across the pool and therefore hidden when the cover was off the pool. Once the pool was filled, the Coverstar was installed and the system commissioned.

“Next, the Calorex engineer commissioned the Delta unit and the pool was up to temperature within seven days, with air temperatures and humidity settings being reached within the same time. To say I was impressed with the Delta is an understatement. As this was our first large indoor pool project, I had no hesitation in speaking to the Certikin team for advice and guidance which was very forthcoming.

“This project has been one of largest projects to date and to see it from humble beginnings to its completion has been both a headache (at times) and an absolute pleasure. I would like to pass on special thanks to Ryan Collins, in the Coverstar department for his patience, understanding and professionalism, especially with the client changing his mind several times at the eleventh hour.

“I would also like to thank everyone at Certikin for providing a one stop shop of first class products, backed up by its knowledgeable staff whose understanding when you need it most is always appreciated but not often thanked.”

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