Sizing a salt chlorinator based on pool gallonage may result in inadequate sanitation — but a few calculations can ensure a correct fit.

While electrolytic chlorine generators (ECGs) for residential pools have traditionally been sized by pool volume, ECGs for commercial pools take bather load into account. Commercial pools are highly regulated, and in order to maintain appropriate chlorine levels, it has proven necessary to know what kind of usage the pool receives. Is it a health club, where exercisers and children swim all day long, or is it a senior center, where members swim only occasionally?

Anticipating usage — and planning for the “worst case scenario” — has made it relatively common to size commercial units based on expected chlorine demand along with volume. Residential units, on the other hand, can be more difficult to judge.

Sometimes new pool owners aren’t sure what their usage will be. Traditionally, it has been easier for homeowners and builders to assume average usage and size ECGs based on volume alone. Gallons are relatively straightforward; usage often isn’t.

But pools with oversized usage and undersized ECGs eventually exhibit problems related to improper sanitation, including hazy water, odors, algae, and even bather illness. An undersized ECG can also lead to shortened cell life, since ECG life expectancy can be decreased when units are overworked trying to maintain proper chlorine levels.

For example, a unit may have a lifespan of seven years based upon a run time of 12 hours per day during the season. If that unit must run 24 hours per day to keep up with chlorine demand, it will last between three and four years rather than the full seven.

It’s difficult to understand the extent of this problem because we don’t know how many salt water pool sanitation issues are correctly attributed to an improperly sized ECG. If a pool owner has repeated issues with maintaining enough chlorine to properly sanitize his pool, do pool professionals ask about ECG size related to pool volume and usage? They may. But they may also attribute the problem to other causes and recommend supplemental chlorine shocks to solve the problem.

So, how can pool builders and retailers size ECGs with chlorine demand as part of the equation?

Calculation factors
Start by having a simple conversation with the pool owner. How many swimmers will use the pool on a daily/weekly basis? Will small children or frequent exercisers be using the pool? (Compared to average swimmers, both tend to add more organics to the water, increasing chlorine demand.) Will pets have an occasional swim? (While not recommended for a variety of reasons, many homeowners still let pets enjoy their pools.) This will start the process of determining whether a pool has a light, medium or heavy chlorine demand.

Then, review other factors that tend to drive up chlorine demand. Are there flowering trees, plants or other vegetation surrounding the pool? Are fertilizers or pesticides used near the pool regularly? Does the climate include unusually warm weather or regular heavy rains? How many hours does the pump run each day? Does the source water contain organic material or added chloramines for sanitation? As one can see, many factors can influence any given pool’s chlorine demand.

These types of questions can help you determine whether a pool will have light, medium or heavy demand during the season. Generally speaking, pools with light demand can stick close to an ECG size based upon gallons (i.e., a 20,000-gallon ECG for a 20,000-gallon pool). Pools with medium demand will need 1.5 times the size (a 30,000-gallon ECG for a 20,000-gallon pool). And pools with heavy demand will
require double the size (a 40,000-gallon ECG for a 20,000-gallon pool).

It’s important to note that these sizing recommendations assume that the pump is running for at least eight hours per day — the minimum recommended run time. Pump run time is an important consideration for sizing ECG units. If the pump will run for shorter periods, an ECG with higher chlorine output should be used.
When in doubt, don’t be afraid to oversize the ECG. While it may cost more for the pool owner initially, that cost will be more than offset by the benefits in water quality and the extended lifespan of the ECG.

If the ECG is sized correctly, it will produce and maintain at least one part per million of free chlorine. (One to four parts per million is the recommended range for salt water pools.) The amount of free chlorine available can be easily tested and measured to ensure equipment is sized appropriately.

Sizing ECGs based on gallons is a fairly straightforward task. Taking usage-related chlorine demand and pump run time into account adds a level of complexity to the equation. However, customers will have better results in the long run if we take the time to factor in pool usage and other chlorine demand factors, which leads to loyal customers, word-of-mouth referrals, and a positive presence in the marketplace.

Source: Bob Harper- Pool and Spa News | 6.10.2011

Source: Rebecca Robledo- Pool and Spa News | 4.15.2011

Electricians and engineers list some common mistakes in grounding and bonding pools

Grounding and bonding can be one of the most confusing parts of pool construction.

So when pool professional and licensed electrician Alan Brotz brings on a new crew member, his first message is very clear: Know your stuff.

“I tell all my guys there is no more important wire on a pool or spa wiring system than a ground wire and a bond wire,” says the owner/president of Swim Systems Inc. in Oviedo, Fla. “The grounding and bonding around a pool are more critical than in any other application in a home, because of the conductivity of water.”

This message applies to pool contractors. Even if local codes require that a licensed electrician handle this critical stage of construction, it’s valuable to know how bonding and grounding should be done.

Here are six common mistakes made by both pool professionals and electricians while grounding and bonding pools, and some guidelines on how to avoid them.

Mistake #1: Confusing the two

Many pool professionals don’t know the difference between grounding and bonding, while others use the terms interchangeably. Even some electricians make this mistake, Brotz says.

But the two are quite different.

Grounding is a process meant to protect people against a possible fault in the electrical system. Basically, it means to electrically attach a piece of equipment to earth ground, which is at the lowest “electrical potential,” mostly referred to as 0 Volt potential. If there’s a fault, or short, the circuit breaker will trip and turn off the equipment.

To ground a piece of equipment, installers must run a properly sized wire from the equipment, through the same conduit as the current-carrying conductors and to the circuit breaker panel. Finally, the wire attaches to the ground bus bar in the circuit breaker panel.

Bonding, on the other hand, electrically ties all specified metallic elements together to minimize the differences in voltage. (In these discussions, voltage is also referred to as potential.) The pump, motor, ladder, even the water nowadays, are bonded.

“If there’s a difference in potential, that creates a foundation for current flow,” Brotz says. “If the current can flow between two pieces of equipment, then it’s just waiting for somebody to come along and be the conductor.”

Brotz gives the example of a pump and heat pump sitting next to each other, with neither bonded. “If there was a fault in the system, either in the pump or heat pump, it’s possible for either piece of equipment to become energized with a voltage other than 0 volts,” he says. “If somebody were to come up and touch the pump, then they become the conductor between the two and get shocked or electrocuted.”

To bond the system, a No. 8 wire runs from one metallic element to the next, connecting to pieces of equipment on a provided bonding lug and, thus, creating an electrical bonding grid. The wire runs through the earth, not inside a conduit.

Mistake #2: Neglecting to ground and bond thoroughly

Because of confusion between the two terms, some professionals may ground but not bond, or vice versa.

Other installers take care to do this with all the pool equipment, but then forget about less obvious things like fences or ladders.

To be clear, anything metallic within 5 feet of the water (meaning the inside wall of the pool), must be bonded. This includes the back of the light niche, ladders (both ladder pockets), diving board stands, lifeguard stands, handrails, junction boxes, pool shells and deck, if they’re made of conductive material. There are exceptions: Any small isolated parts of less than 4 inches in any dimension and extending less than 1 inch into the structure, such as rope hangers.

The pool’s rebar must also be bonded, as well as any reinforcing steel under the deck within 3 feet of the inside of the pool wall. If there is no reinforcing steel in the deck, at least one bare No. 8 (or larger) buried wire may be used, if installed in accordance with code requirements.

Generally speaking, all electrical equipment associated with the pool must be grounded.

Mistake #3: Grounding and bonding to earth

Some professionals believe that grounding can be done by driving an 8-foot ground rod into the earth and hooking the grounding wire to it. “That will not conduct fault current to trip the circuit breaker,” Brotz says. Some may believe this sends any stray current to the earth, but that’s not the purpose of grounding.

Any defective piece of equipment will remain energized. “Then when somebody comes up and touches it, it’s, ‘Good night, nurse.’” Brotz says. “That ground rod will do absolutely nothing.”

Some will even try using the earth as part of the bonding conductor. “In other words, you bond the pool together, drive a ground rod; bond the pad together, drive a ground rod. But you don’t run a wire in between,” says E.P. Hamilton III, Ph.D., P.E., an electrical engineer and president of Hamilton & Associates in Pflugerville, Texas. If you do this, the system isn’t bonded, because everything must be tied together. Otherwise, you risk current straying, if the potential between two components is different.

Mistake #4: Using the wrong connectors
When hooking up the bonding and grounding wires to a piece of equipment, you want the best connection possible to ensure that any current that needs to move has a clear path.

That’s why tying or wrapping the wire around a bolt or other metallic component on the equipment won’t do the trick. “It doesn’t insure any sort of reasonable electrical contact, particularly over time,” Hamilton says.

Instead, use clamps or lugs rated for the specific wire size and application. For instance, when connecting the wire to the pool’s rebar grid, you must use clamps that are UL approved for concrete encasement. If they’re going in the ground, the tag should indicate that they are approved for direct burial. These clamps are usually made of brass and copper. The screw should be made of stainless steel or brass. You don’t want plated steel anywhere near these applications, or they will rust and eventually fail.

“As to ones that are not required within concrete, then they’re going to be standard electrical fittings like you would get at an electric supply house,” Hamilton says.

Make sure the connectors are listed for the type of wire you’re using, whether it’s stranded or solid. Electrician and pool professional David Durkin often sees stake-ons, bud connectors and terminals used with solid wire. “They will become loose after a while, because it’s supposed to mesh in, and you can’t mesh into a solid wire,” says the owner of D&M Electric in Antioch, Calif.

Conversely, you can’t wrap stranded wire around a screw. “It keeps pushing out strands, and it’s not a good connection,” Durkin says. “They should be using terminals.”

If you do want to make the connection by wrapping solid wire around a screw, wrap it clockwise, he adds. “When the screw tightens, it sucks the wire instead of pushing it out.”

When you have to pot certain connections, such as those inside a light niche, use potting kits made for that purpose. Don’t use things such as bath tub caulk, Hamilton says.

Mistake #5: Using the wrong wires
Watch where you use insulated wire. Particularly on the equipotential grid under the deck, uninsulated wire is mandated by code. Some electricians prefer this variety on the whole bonding grid to maximize contact with all relevant pieces of equipment, the water, earth and all conducting surfaces in contact with the bond wire.

There is one place where you must use an insulated wire: “If you have a non-metallic conduit going from the light niche up to the junction box, you have to pull an insulated No. 8 green wire through there,” Hamilton says. “But even that’s more of a ground wire, even though it does have some involvement in the bonding system.”

Many codes require that No. 8 wires and smaller be solid. If you’re cautious by nature, use solid wires for No. 6 as well. “If you need a wire that’s that small, you’re better off with a solid wire, just because the strands are more susceptible to environmental damage,” Hamilton says.

This is especially important with bond wires, since they’re in direct contact with the earth. “It may be buried 50 or 60 years,” Hamilton says.

Mistake #6: Believing that plastic or fiberglass elements need bonding
This mistake is generally not made by professionals, but rather by inspectors. Many of them, for instance, see the metal tension band on a plastic or fiberglass filter and insist that it be bonded.

“Don’t do anything to the tension band on that filter,” Hamilton says. “That creates a substantial safety hazard…if you do anything to the tension band. You’re affecting its mechanical integrity and ability to hold the filter together over time and under pressure.”

If that filter comes with a bonding lug, or has a metallic base with a bonding lug, then it must be bonded. But if it’s all polymer on a polymer base and it comes with no bonding lug, then it doesn’t need to be included in the grid.

Explain to the inspector that, because the band is only touching the plastic filter shell, there is no electrical connection. If the inspector won’t budge, then move the equipment so it’s more than 5 feet away from the inside wall of the pool.

You may have the same problem with plastic lights outfitted with an all-plastic niche. Show the inspector that UL has listed it to go ungrounded.

Take a slightly different path when installing double-insulated pumps, Hamilton says. Though you can’t bond them now, code requires that you run a bonding wire to it anyway. You won’t make the connection to the pump, but you must connect the bond wire to the ground wire in the junction box serving the pump. The code requires this so that if the double-insulated pump is replaced with a pump that isn’t double-insulated, then there’s a place to bond it without tearing up the pool area.

Source: Rebecca Robledo – Pool and Spa News | 5.13.2009

Industry veterans offer tips for ensuring a perfect automatic-cover installation.

Installing automatic pool covers requires a team effort, with the builder and subcontractors playing important roles.

“The pool cover installer should make sure they’re coordinating with whoever is building the pool,” says Mark Sheinman, president of Pennco Automatic Pool Covers in Havertown, Pa. “You need to make sure everyone’s on the same page.”

Here, specialists explain how all parties can contribute to a long-lasting automatic cover.

BUILDERS:
• Make everything square and follow the specifications.

The most important part of the automatic-cover installation rests in the pool builder’s hands. Unfortunately, it’s also where most mistakes are made.

“Most covers will work well for the first couple years, but after that, you’ll start to see issues if the pool is out of square or not constructed correctly,” Sheinman says. “The customer starts having little problems like, ‘It was out of alignment today,’ or, ‘It didn’t close evenly.’ You just won’t have consistency in operation.”

For the cover to glide smoothly through narrow tracks, several elements must be precisely aligned. To make this happen, builders need only to take a little extra time to make sure the pool is level, plumb and square — and built to the planned specifications.

And remember: No improvising on the job. If the pool plans need to change, coordinate with the cover installer so everyone is up to speed.

• Set up proper drainage.
Even the newest hydraulic cover systems and waterproof motors are not meant to sit submerged in water, but that’s exactly what will happen if the cover mechanism box floods out due to rain, pool overflow or ground water.

Some cover installers prefer when pool builders drain the cover box to daylight, with the pipes gradually sloping until they empty out to daylight at a lower level. This usually requires a gradual slope in the yard, but on flat sites, the pool sometimes can be slightly raised to create enough of an elevation differential.

“Then there’s very little to no chance that the mechanism enclosure could flood or clog up,” Sheinman says. “It’s the least expensive method, and extremely effective.”

On sites that won’t accommodate this scheme, there are other options. Some like to send the drainage to the sewer. Before doing this, make sure it is permitted by local code.

Another possibility is to dig a dry well with crushed stone on the bottom. However, be aware that dry wells probably will require some maintenance. For instance, when the soil doesn’t drain properly, it can get backed up and flood out the mechanism enclosure.

Some builders don’t like to tie this system in with the deck or backwash plumbing. If the other systems back up, they say, gravity will send water right into the lower-sitting cover box.

As with pools, larger pipe is generally better when plumbing a drain. Sheinman prefers 4-inch plumbing, so that leaves and other debris can move more freely. Three inches is just adequate, he says. If you go with 2-inch plumbing, though, the drain may have to be snaked more often than the homeowner likes.

In addition, use sweep 90s rather than hard corners — these make it easier to get a sewer snake through for unclogging.

Drains can be placed throughout the box, as you would on a deck. However, many
installers recommend placing them on the ends of the mechanism enclosure, so they’re more accessible to service techs for cleaning.

• Make stone lids service-friendly.
Builders often choose to integrate their cover boxes with the deck by covering them with stone or a cementitious material.

That’s forward-thinking in terms of design. But consider how this will affect service down the road. A single technician can only lift so much, which is why Nikk White recommends breaking the lid up into sections that max out at 50 pounds.

“If it weighs 75 pounds and you have to drag it off and pinch your fingers, [service techs] are going to ignore it and not do it,” says the service manager of Cascade Pools in Lake Oswego, Ore.

If possible, he may use hollow artificial rock to make for a lighter product.

When using a natural, flat material such as flagstone, keep the joints between the sections separated — do not grout them together.

“You have to break the grout to get the lid off,” White says. “Some masons say, ‘It’s silicone.’ But you still have to cut it, and then it’s going to look like heck. It’d be better not to put anything in there in the beginning.”

• Provide proper support for deck-mounted installations.

These applications — where tracks are placed on the deck to cover a freeform pool — will only work on a stable surface. Otherwise, the deck won’t properly hold the tracks.

Pavers that sit directly under the tracks or other cover components should not simply be installed on a sand bed.

“It’s important to either set the pavers in concrete, or have concrete between them to lock them into place,” Sheinman says. “When you do, you have a good, permanent foundation that’s not going to move over time. Otherwise, you’re going to have problems long-term with the installation.”

Source: Rebecca Robledo- Pool and Spa News | 3.27.2009