Specifying/Building A New Energy-Efficient Concrete Pool
The advice provided below, is not intended to cover aesthetics or to contravene instructions by the manufacturers of pool skimmers and drains, nor to contravene any local regulations. Please consult local laws, city and council requirements before building your new pool.
Specifying and Building an Energy Efficient new pool
Pools often use one-third of the total electricity of an average household with an average pool.
To minimise this and enjoy a quality, trouble-free pool, it is essential that the plumbing, pool equipment and control system are correctly designed and installed.
If you make a mistake in the construction of your pool, you will likely have to put up with it, and pay for it, for the 40-year life of the pool.
You need to think of the pool as an integrated system, and not just as a collection of equipment cobbled together from different manufacturers. You need an integrated system that operates well. Your equipment needs to be correctly plumbed, matched, integrated and controlled.
We recommend that you work very closely with the pool builder closely to achieve this.
- Decide clearly what you want up-front. There are some ideas (here).
- Specify What You Need from your Pool Builder
To get a quality pool it is essential that the plumbing inside the concrete shell of the pool is correctly sized, located and installed. You will NOT be able to correct this once the pool is built.
The following is a guide as to how to achieve this.
In many pools, up to half the work the filtration pump performs is overcoming flow resistance in just the pipes. This does not have to be so. A few simple, inexpensive changes will make a large difference to the functionality, energy efficiency and running cost of your new pool.
- Use the Correct Pipe Size.
If your pool equipment is below the waterline in your pool, use a minimum 50 mm PVC pipe in pools from 30,000 litres upwards. An example is here.
The reason is simple. The flow resistance of the more typical 40 mm pipe is about 2.5 times the flow resistance of a 50 mm pipe. In addition, the flow resistance through 50 mm pipe fittings such as bends and valves is much more than in 50 mm. The pump has to work harder and this uses more energy. This adds up over the 40-year life of a pool to a lot of energy, pollution and wasted money.
If your pool equipment is going to be above the surface of the water, then you should use 40 mm for the return pipes and 50 mm pipe for the suction lines. The reason is that these pools generally have multiple air traps in the piping and it is easier to clear air or hydrogen generated by the chlorinator out of a 40 mm pipe than out of a 50 mm pipe. This is usually more important than considerations of flow resistance.
- Minimise Pipe Height changes
Any air or gas rises to the top of any piping system. If there are multiple height changes in the plumbing, then you will probably get multiple inverted loops, each, like an inverted U, and gas will collect in each. Each of these inverted loops then requires additional pressure from the pump, as well as a large flow of water to clear the gas. If you have 5 inverted loops for example, you will have 5 lots of additional water pressure adding together that the system has to overcome to clear the trapped air or gas. This means that your system requires a larger pump, running faster than you would need.
You can save a large amount of energy and running costs by using an appropriate control system for your pool but the savings will ultimately be limited by the plumbing and its constraints and loops. If you have gas traps on the inlet side of the pump, then priming the pump will also be more difficult and take more energy.
Inverted loops and trapped gas are very common in pools where the equipment is above the surface of the pool, and especially if the plumbing is threaded up and down through the steel reinforcing of the pool surrounds. Aim to run all of the plumbing at the height of the respective inlet or outlet in the pool. For example, do not run Return‐To‐Pool pipes them from the filter along the pool edge above the water surface and then down to the Return‐To-Pool outlets. This will create a large gas trap. Instead, please run the pipes for as far as possible, either below or at the level of the Return‐To‐Pool outlets. This allows any gas trapped in there to bubble out without being trapped. The same applies to the inlet from the skimmer(s). Starting from the skimmer, please stay at a constant height below pool water level with your piping, all the way until you get to the filter and then come up vertically as close to the filter pump as you can. Similarly, the Return‐to‐Pool pipes should go vertically down to their final depths as close as possible to the filter outlet.
- Use the minimum number of bends and other fittings
Like your car, water flows much more efficiently and economically on straight runs than it does on bends. Minimise the number of bends and especially minimize wrapping pipes around concrete reinforcing as much as possible. Don’t do it unless it is essential. Every bend is a potential blockage, leak or air trap, as well as an energy waster.
- Use sweep bends not sharp 90 degree bends
Like your car, water flows most efficiently and economically on gradual bends than it does on sharp, right angle ones. Sweep bends in your plumbing will save you a lot of energy. Use sweep bends where possible though if you have difficult sourcing these, use two 45-degree bends in series.
- Skimmer Boxes
Most pools use a skimmer box set into the concrete. Make sure that:
- it is set at the correct height for the desired water level. There are many that are not.
- if possible, place it on the down-wind end of the pool where it will pick up leaves and rubbish blown there by the wind,
- it is located such that the pool water circulates past it, such as in the middle of the down-wind wall.
- Do not just put it in a corner to ‘get rid of it.’ It is very important to the cleanliness of your pool that it be able to skim the water efficiently.
- Of course, you don’t want the skimmer where it will cause a nuisance to you when swimming laps and you need to place it sensibly. A good default position is the middle of the long, down-‐wind wall in a rectangular pool.
- It is also a good idea in larger or windy pools to consider having two skimmers. They could each be, say 1 metre, from the ends of the long down-wind wall.
- If you do have 2 skimmers, then run both skimmer pipes back to the filter as individual pipes. This arrangement allows you to ‘tune’ the water flow when setting up the pool equipment. It also means that a broken pipe caused by earth movement and the like, can be isolated if required. If running both pipes is not convenient, run the pipe from the furthest skimmer as directly as possible back to the filter as a straight pipe and connect the nearer skimmer into it with a T, and not the other way around.
- In-Floor Cleaners
In-floor cleaners are attractive in some ways, however, they are more complex and troublesome than other types of cleaners. And they tend to use a lot more energy. If you put pipes under the shell of an in‐ground pool for either an in-floor cleaner or a main drain, please ensure that the builder is experienced and knows how to cushion and protect such pipes from the pool settling. There are published standards describing how this should be done.
Remember that when you fill a pool, you will have be adding 1 tonne of mass per 1000 litres of water and pools can, and do, settle a little. As long as the pipes and shell are correctly designed and installed this should not cause an issue, however, if they are not they can crack and you will have a leak that is very difficult to repair.
- Return to Pool Pipes
There should be at least 2 individual return-to pool-pipes bringing filtered, chlorinated water back to every pool. They should be placed about 150 mm below the water surface and set so that they create the maximum amount of circulation in the pool surface layer. This conveys floating rubbish, dust, body oils, suntan cream and leaves to the skimmer and thence to the filter.
In a rectangular pool, the return-to‐pool outlets should be in diagonally opposite corners, set in the short walls about 300 mms from the corners. They should exit the walls horizontally with the water flow parallel with the long walls. If you have some dead spots, such as at steps or in corners where there is likely to be poor circulation of surface water, consider adding another return-to‐pool pipe there. Such additional pipes should be in 40 mm pipe (or smaller if the pool equipment is to be above the water surface).
- Pool Sweeps
Do allow for a pool sweep with an outlet for the sweep hose in the pool. This is especially so if you have lots of leaves in the pool.
This requires an additional pipe which can be plumbed in 40 mm. This should terminate in the appropriate fitting for the cleaner (usually a threaded socket) about 200 mm below water level in the centre of the up‐wind, long wall of the pool. Even if you are not planning to use a pool sweep immediately, it is much easier and safer to plumb it in when you are building the pool. This type of pool sweep is superior in our view, to the suction type for reasons explained here.
- Solar Heater
There are two basic alternative arrangements for pool solar heaters:
- An independent plumbing circuit,
- An heater in-line with the filter pump.
An independent plumbing circuit means that you can run the solar heater independently of the pool filter. For this, you should have two, wall‐suction points at least 1 meter apart, set in a wall at a convenient point and not less than 500mm below the surface. This is usually best done in the long walls of a rectangular pool.
The system draws water from them and there are 2 inlets to minimise suction hazard as is done for main drains. The inlet pipes should be 50 mm and be plumbed directly together with a straight run of pipe that goes go to a pump that pumps water to the roof solar heater.
The up-pipe to the roof may be 40 mm for aesthetic reasons as 50 mmm looks very large when run up house walls. The solar return-to‐pool from the roof should be a 40 mm pipe that is insulated to retain heat. It should connect to an additional return‐to‐pool heater outlet, deep in the deep end, angled down at about 30 degrees from the horizontal and pointed in the same direction as the circulation caused by the Filter Return-To‐Pool pipes near the surface.
This overall arrangement is to allow the hot water from the roof to heat the colder water in the bottom of the pool.
Many pools have a solar heater added as an after-thought. In this case, the water for the solar heater comes from the pool filter. This means that the pool filter must run to provide water to the solar heater pump. If you have Time-of-Use electricity, then this is expensive as solar heating occurs during shoulder and peak tariff periods. Moreover, using simple time-clocks, you need to run the filter at full speed most of the day, in case the solar heater needs to switch on. This can be very costly.
A better way to manage this with big savings is to use Pooled Energy’s Solar optimiser for pool heaters. This only switches the filter on when the solar pump needs to run. See (here).
- Test Before You Pour Any Concrete
Once a pipe is embedded in concrete, you may need a jack-‐hammer to repair any leaks. Don’t risk it! Have the pipes pressure tested before you pour.
If you are pouring a lot of concrete onto plastic (PVC) pipes, consider pressurising them during the pour. If they are full of water under pressure during the pour then heavy concrete, large workmen and heavy implements are far less likely to damage them than when they are empty. Also, if you do damage them during the pour, leaks will generally be visible due to water pouring out and can be repaired on the spot.
A good way to do this is to connect the pipes to a hose whose end is taken up a convenient tree or height. Run water into the hose using a T piece so that it dribbles out the end that is up the tree and your pipes will be pressurised. Such precautions are generally only necessary in the more extreme situations with large concrete pours and usually unnecessary when the pipes are near the surface of a pour or spray. You should also consider using higher grades of pipe in the extreme cases.
- Use at least Class 12 Pipe
Most pipe used in pools is Class 9 and is too light for long-term reliability. Classes 12, 15 or 18 pipes are much stronger and are readily available and will fit all the same connectors and sockets. Use no less than Class 12.
Class 9 is prone to damage during the concrete pour. If it is damaged, repair often requires jack-hammering the pool shell. It is better, for an asset that needs to last 40 years, to spend a little more on the grade of pipe.
When you do pour the concrete, make sure the pipes are adequately sealed at both ends. It is amazing what gets into some pipes. Lumps of concrete, stones and cement dust are not good for your pool or your equipment.
For heater outlets use Class 18 pipe to minimise pipe failure due to hot water
- Photograph the pipes before you pour concrete on them and label them as to which is which.
- Pool Equipment Mounting Pad
You will need a pad on which to put the Pool Equipment. The best pad is made of concrete but bare earth with concrete slabs can be used where required.
If you have adequate room, allow a pad of a minimum 1.5 metres long by 1 meter.
If you plan to have pool sweeps and solar heaters with pumps as well, you will need 2 m x 1m.
You can cramp the installation but you will pay generally for that by being forced to use sharp radius bends in the piping and thereby incur somewhat higher running costs. You will also need a pipe to waste, that is, to the sewer. This should be 50 mm. Please bring your pipes up vertically from the pad, evenly spaced along the 1 metre edge with all the inlet pipes in a group and all the return pipes in another group.
A typical sequence of pipes for a larger pool might be:
Skimmer Box 1
Skimmer Box 2
Solar Inlet from pool
Solar Up to roof
Solar Return from roof
Solar Return to pool
Pool Sweep-line to pool
Waste to sewer
If the equipment pad is above the water level of the pool, then you do not need any isolation valves on these pipes. If you are below the surface of the pool, you will need to have an isolation valve on each pipe (except the solar roof‐pipes) to prevent water flooding out if any one pipe needs to be disconnected. Please make sure that your builder uses quality valves that are easy to turn (and automate), such as Jandy17
17. Mains Power supply
You will need a single 240 V, 10 amp (USA 115V, 20A) mains power outlet for the filter pump and chlorinator, connected via a safety switch (an Earth Leakage circuit‐breaker or ELCB). For each additional conventional pump, such as the solar heater pump or the pool sweep, please allow an additional 240 V, 10 amp socket (USA 115V, 20 A).
If you have a heat-pump, you will need a dedicated 240V 15 Amp circuit. A good idea with new construction is to have a 3 phase sub-board for the pool.
- Pools with Spas
Many pools have attached spas where water from the pool filtration system flows into the spa which then overflows back to the pool via a small waterfall. This is a good idea as it keeps the spa water fresh.
Many such pools have a shared filter, that is, a filter that is used for both pool and spa. This requires a large number of valves to switch the filter ‘over’ from pool to spa and vice versa. This is a manual operation and we have seen one that required 24 valves to be operated. Fundamentally, the requirements for filtering a pool with low pressure and filtering a spa with high pressure jets, are very different and trying to use the one filter for both is not a good idea. It is also labour intensive.
We recommend that you keep the pool and spa systems essentially separate. Please consider installing a totally separate filter, pump and high‐speed jets for the spa, connected with a single pipe and valve. This by far the best and most convenient way. By all means, also return the solar heater water via the spa if you so wish. Cartridge filters are generally a good inexpensive choice for spas bit sand (media) filters are recommended for pools.
- Equipment Enclosures
It is always a good idea to have an enclosure for pool equipment to protect it from sunlight, however, it is not strictly necessary. Many local Government bodies such as local councils, do however insist on acoustic enclosures to reduce the noise of pumps to acceptable levels.
If you have Pooled Energy system, it will be acoustically quiet and it is unlikely that you will need an acoustic enclosure for it, and so you can have an enclosure that is aesthetically more acceptable (and less expensive) than a typical acoustic enclosure. You can also readily put the equipment indoors or under houses with no appreciable problems in most cases. There are two exceptions. Firstly, if you have additional pumps, such as pool sweeps or solar pumps, you may wish to, or need to. acoustically enclose as they are typically much louder. Secondly, if the Pool Equipment is above the pool water level, the filter pump will be noisier than if the equipment is below.
Please see the precautions about acid storage (here).
- Filling your new pool
Fill your pool as soon as possible, especially if there is rain. Pools can ‘float’ out of wet ground with catastrophic results.
If you have a Pooled Energy pool, when you fill your new pool, please put just water in it and NO Chemicals at all. Pooled Energy will set‐up your chemicals for you. If chemicals are added by another party, it may necessitate us draining and refilling the pool to redo the chemical set-‐up correctly. Even salt can also be a problem if it is low grade salt with impurities.