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Swimming Pool Expert Witness - Paolo Benedetti

12 Reasons To Use An Electronic Auto-Fill on Swimming Pools



Autofill Pools with a Jandy Levolor

Electronic auto-fills are slightly more expensive, but they offer important features required by edge vessels. They are far superior to float or bobber auto-fills for a number of reasons.

1. Electronic fills can activate huge fill lines for larger pools and water parks. The 24vac can activate any size irrigation valve. On a typical edge pool, I use a 1” fill line (compared to 1/4” on bobbers). A bypass line can provide for manual filling.

2. A maximum fill timer protects against catastrophic failures & overfilling. In the event there’s a pool leak, the auto-fill will cease. It will reset in 24 hours or when the power is turned off/on.

3. There is an activation delay, so minor waves from bathers or wind surges don’t cause needless filling.

4. There is no annoying hissing from the bather surges or waves.

5. There is not a large well of stagnant water for algae to grow in. By incorporating an overflow, a standpipe can periodically self-flush.

6. The activation delay eliminates frequent water hammer in the plumbing.

7. A 2” stand pipe is easier to hide in a beam. In fact with some ingenuity, you can incorporate an overflow line as well.

8. The fill tolerance is more precise – excellent for smaller or shallow vessels.

9. They are available with a high level sensor to activate edge pumps if bathers forget.

10. They can be placed on a relay and activated on a schedule. This is beneficial if the property is on a well, storage system or has an irrigation booster pump.

11. The fill line can be plumbed into a return line (non-edge vessels).

12. They are applicable to surge tanks of any depth. Bobber auto-fills are restricted by the depth of the well housing or the length of persons arm.

Sensor standpipes should be set 3-6 inches above the floor of the catch basin. The sensor tips should be set at the 12” minimum operating level. The fill line should ALWAYS be in the surge tank/catch basin on edge pools. Placing the fill line low on the end wall eliminates splashing & noise.

I’ve only had one issue in 20 years – a leaf got stuck across the probes and the unit failed to sense a low water condition. Now I place a perforated suction cover on standpipe opening to prevent debris entry.

Swimming Pool Expert Witness

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Paolo Benedetti is the President of Aquatic Technology and better known on social media as the "Swimming Pool Expert Witness". Paolo is an instructor at Watershape University and has authored a myriad of articles on the finer points of pool construction and design. He is a pioneer in the field of aquatic design, constantly pushing the envelope, creating a number of firsts that spawned new trends in the industry.

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Hair Entanglement in Pools, Are Current Standards Adequate?



Hair Entanglement in Pools, Are Current Standards Adequate?

When discussing hair entanglement in the pool and how to prevent these types of incidents from occurring, we have to look at a few things. The first is line velocity. If it is low enough, hair won’t be ingested by the pipe and tangled under the drain lid. Suction entrapment wouldn’t occur either, even if a grate were missing.

Video captured a teen girl nearly drowning after getting her hair caught in the pool.

The second issue pertains to the current codes and standards. Some states have state building codes that dictate maximum line velocities for energy efficiency. California and Florida both mandate line velocities of 6 FPS suction and 8 FPS returns for energy efficiency. 

Current Standards

Residential In-ground Pools NSPI-5/2003 (9.2) the line velocities were limited to 8 FPS suction and 10 FPS returns. (9.2.1) the limit through the drain cover was limited to 1.5 FPS.

Residential In-ground Pools NSPI-5/2013 (9.2) the line velocities were limited to 8 FPS suction and 8 FPS returns. (9.2.1) the limit through the drain cover was deferred to the APSP-7 standard.

Suction Entrapment Avoidance APSP-7 (2013) Piping line velocity is not specified, though the flow rate through the drain cover is limited to 1.5 FPS.

APSP-15 Energy Efficiency Code (2011) 6 FPS suction and 8 FPS return

ISPSC 2015 (311.3) limits the line velocities in the return piping to 8 FPS.  (310) It defers to the specifications in APSP-7 (there is no longer a suction line velocity in the standard).

Suction Outlet Fitting Assemblies APSP-16/2017 (3.9.2) piping line velocities were eliminated, though 1.5 FPS remained as the line velocity through the RDP/SOFA.

RE: Hair Entanglement In The Pool - Decreased distance between the suction pipe and the underside of the drain cover increases the flow through the drain cover.
Decreased distance between the suction pipe and the underside of the drain cover increases the flow through the drain cover.

The safety standards are not addressing energy efficiency. Most experts agree that the optimum efficiencies are achieved at 6 FPS suction and 8 FPS return line velocities. The majority of hydraulic engineers are designing at 4.5 FPS suction and 6 FPS return line velocities. This allows for a margin of error and minor deviations that may occur during construction, while still staying below the maximums. Most codes for public pools recognize the need for low line velocities and therefore limit the velocities at the pipe connected to the main drain to 1.5 – 3 FPS.

The safety standards assume two things occur. The first assumption is that the drain sump size is compliant with the SOFA requirements and the manufacturer’s specifications.  Field-built sumps (divots carved out of the shotcrete) are oftentimes too shallow. Few builders thicken the shotcrete around the suction pipes to allow for a proper depth sump.

The decreased distance between the suction pipe and the underside of the drain cover increases the flow through the drain cover. This increases the danger of hair entanglement, as the design standards and flow rate through the cover have been exceeded. Therefore the sumps are of insufficient size and volume to slow the velocity of the water.

Swimming Pool Expert Witness

Photo Credit: Getty Images

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Swimming Pool Expert Witness - Paolo Benedetti

Utilizing Drainage Mats In Pool Construction



Pool Contractor Using Drainage Mat During Pool Construction

Retaining walls, raised pool bond beams and pools with adjacent upslopes all require drainage behind them. But it is impossible to install drainage rock up the walls of a shotcrete pool, without extensive over-excavation, forming and backfilling.

Instead of ignoring these conditions, wise contractors utilize drainage mats installed upon the earth, prior to the placement of the shotcrete. This allows the subterranean water to drain vertically into the drain rock under the pool, where it can be collected and discharged (drained to daylight or via a sump pump).

For high-end projects or all tile vessels, this is critical in reducing negative side water infiltration from the soils. Water passes through the geofabric and into the air gap created by the dimples in the plastic sheet. The drainage mats are available with dimples of various sizes to match the anticipated water flow.

Drainage mats can also be used horizontally between coffers and vessels to assist in the lateral discharge of water. The drainage mats can be nailed to the soil prior to steel placement or utilized in place of steel-tex.

Photo Credits: Carlisle Coatings & Waterproofing Systems

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Swimming Pool Expert Witness - Paolo Benedetti

Indoor Pools & Water Vapor, What You Need To Know



Indoor Pools & Water Vapor, What You Need To Know

Indoor pools are very unique. The water vapor escaping from the pool is trapped in the building envelope. These vapors are potentially corrosive, as they contain chlorine, chloramines, or ozone. The water can have destructive consequences and pose serious health issues if the building is constructed incorrectly.

Dehumidification of indoor pools is absolutely essential in order to avoid costly damage and repair work.
Dehumidification of indoor pools is absolutely essential in order to avoid costly damage and repair work.

Dehumidification for Indoor Pools

There is no such thing as an oversized dehumidification system. But the lack of a dehumidifier (or an undersized one) allows the water vapor to accumulate and penetrate the building envelope. Water vapor inside the walls can cause corrosion of the structural beams, braces, and brackets, corrosion of the wiring and electrical components, foster mold and algae growth, rusting of HVAC ducts, or promote dry rot of wooden elements. Excess water vapor in the building can lead to a series of air-borne health maladies or bacterial infections.

Indoor pool mold from excess water vapor.
Indoor pool mold from excess water vapor.

Been There, Done That

Cheap clients who do not want to pay for the installation or operation of a dehumidification system, think that they can reinvent the wheel with exhaust fans, sliding doors, skylights, ceiling fans, or other schemes. Trust us, they have been tried countless times without success.

Proper Building Envelope for Indoor Pools

It is important to install a vapor barrier and use moisture-resistant construction materials to prevent the migration of moisture into the walls and ceiling. Electrical outlets, fixtures, and penetrations must be sealed against vapor intrusion.

Without Vapor Barrier vs With Vapor Barrier - Indoor Pools
Indoor Pools – Without Vapor Barrier VS With Vapor Barrier – Photo Credit: Aquatic Mechanical Design

Air Pressure in Indoor Pools

The air pressure within the swimming pool enclosure must be less than the adjacent spaces. Maintaining a high pressure in the adjacent spaces ensures that the water vapor does not migrate.

Operational Cost

Operating a dehumidification and air handling system to control the air pressures, temperatures and humidity are expensive to operate. Failure to operate these systems properly will result in vapor migration and degradation of the building. Maintaining the proper temperatures is also important in controlling the creation of water vapor (evaporation).

Automatic Pool Cover

Using a pool cover does not eliminate the need for a dehumidification system. It will help reduce the vapors, but it will not eliminate them. The installation of a cover allows for the reduction in the size of the dehumidification system, as the loads are reduced.

Qualified Indoor Air Quality Expert

We do not profess to be experts in this field. Though we have built a number of indoor pools, we rely upon specialists in this field. Most mechanical engineers or dehumidifier manufacturers do not possess the skills to properly design the HVAC/Dehumidification system, vapor barriers, building envelope, ducting sizes, or air handling register/return locations.

Non-Corrosive Air Ducts

Properly constructed indoor pool air handling systems utilize non-corrosive plastic ducting, registers, and returns. Galvanized sheet metal ducting quickly begins to corrode in an indoor pool environment. Indoor pools can be a source for year-round enjoyment of a pool. But they require a properly designed and built enclosure, in order to protect the rest of the building and occupants’ health.

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