POOL PLUMBING

Plumbing Systems

To understand the basic plumbing system of a pool or spa, you must follow the path of the water.

The water from the pool or spa, not both at the same time, enters the equipment system through a main drain on the floor, through a surface skimmer, or through a combination of both main drain and skimmer. It travels to a three-port valve (if there is no spa, there will be no such valve) and into the pump, which is driven by the attached motor. From the pump, the water travels through a filter, then to the heater, and back through three-port valves to the pool or spa return lines.

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Skimmers

The purpose of the skimmer, as the name implies, is to pull water into the system from the surface with a skimming action, pulling in leaves, oil, and dirt before they can sink to the bottom of the pool, thereby providing a conveniently located suction line for vacuuming the pool. Most skimmers today are molded, one-piece plastic units. Older pools have built-in-place concrete skimmers. Some pools have more than one skimmer.

Most skimmers are built into the deck, and are accessed through a cover on top (the cover will be plastic or concrete) or by reaching into the skimmer through the opening that faces the pool itself. Some Skimmers, as with portable or above ground pools, are separate units that hang on the edge of the pool (in the water or outside of it). Redwood hot tubs use a flat, vertical skimmer that has no basket but skims the surface and pulls any floating debris to a plastic screen. Some portable spa skimmers have a cartridge filter built in. Some pool skimmers include automatic water level controls and automatic Chlorinators.

The water pours over a floating weir that allows debris to enter, but when the pump is shut off and the suction stops, the weir floats into a vertical position, preventing debris from floating back into the pool. Some skimmers have no such weir and use a floating barrel as part of the skimmer basket. The purpose of the basket is to collect leaves and large debris so they can then be easily removed. The disadvantage of both types of weirs is that leaves can cause them to jam in a fixed position, thus preventing water from flowing into the skimmer. When this happens, the pump will lose prime and run dry, causing damage to its components. Therefore, during windy periods it might be better to remove the weir from the skimmer to prevent such problems.

You should exercise care when working around the skimmer when the pump is on. Keep small objects away from the skimmer opening when the basket is removed and especially keep your hands from covering that suction hole for it may be dangerous. You may invariably end up clogging the pipe at some turning point where leaves, hair, and debris later catch and close off the pipe completely.

There are two types of skimmer plumbing. The first one has a single visible suction port or opening. Actually the pipe from the main drain and the pipe from the skimmer connect just below the visible opening and a combination Diverter is inserted to regulate the amount of suction from one or the other. A neck on the Diverter extends up from the skimmer bottom for attaching your vacuum hose when cleaning the pool.

The value of this system is that when vacuuming the pool, you can divert all of the pump suction to the skimmer bottom, in effect, shutting off the main drain. The Diverter also has a nipple aligned horizontally to the opening. Usually when the nipple faces away from the pool, the flare on the bottom of the Diverter closes the main drain pipe and all of the suction from the pump is now at the skimmer. When the nipple faces toward the pool, the body of the Diverter closes the pipe from the skimmer and all of the suction is now at the main drain. Choice between these two settings will divide suction between the skimmer and main drain.

Depending on needs a pool has its own settings. For example, if the pool gets more leaves than dirt, the Diverter should be set to make the suction in the skimmer stronger than in the main drain. That will help the skimmer pull the leaves into the skimmer basket. If the pool tends to get more dirt or sand than leaves, the Diverter should be set to strengthen the main drain suction. When dirt falls to the bottom of the pool, the strong suction from the main drain will pull the dirt toward it. This is also helpful when brushing the pool bottom, because suspended dirt will be pulled into the main drain.

Diverter units are made of plastic or bronze. The bronze Diverter are heavier and better than the plastic ones. If the suction from the pump is not strong, the plastic ones tend to come loose and float out during vacuuming . They also tend to rotate in the skimmer as you work, changing the amount of suction in the skimmer from what you have set.

The other type of skimmer plumbing has two separate ports, one pipe that goes directly to the main drain or to an equalizer line, while the other goes directly to the pump. Usually the port farthest from the pool edge is the pipe that goes to the pump, and the port closest to the pool goes to the main drain or equalizer line. An equalizer line is simply a pipe that extends from the skimmer bottom down 18 to 24 inches and through the pool wall just below the skimmer. In this type of skimmer, a Diverter plate regulates the suction between the main drain and the skimmer.

In both styles of skimmer, the idea is that if the pool runs low on water, the pump can pull water from the bottom of the pool via the main drain instead of the empty skimmer, or from the side of the pool below the skimmer in the case of the equalizer line, so the pump will not run dry.

Some older (often concrete) skimmers have odd-sized ports that can't accommodate your vacuum hose. In these cases, a special cover plate can create a generic adapter.

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Main Drains

The main drain has one or more plumbing ports. One port feeds a pipe to the pump. In a spa, there might be several ports for several pipes leading to different pumps (for jet action).

Another port is a one-way valve or the check valve that allows water that might collect under the pool to enter the pool, but no water can flow out. Water collecting under the pool creates extreme upward pressure that can crack the pool. This pressure, called hydrostatic pressure, is relieved by this valve.

Hydrostatic pressure is an important consideration when planning to drain a pool for any reason. Obviously it is not wise to drain a pool completely during the rainy season or if there is any other suspicion of groundwater.

In some spas, there might be more than one main drain so that if one becomes covered with a foot or hand, water is pulled from the other, avoiding injury to the bather. These drains are usually located at least 12 inches apart. Because spas are relatively shallow, strong suction can create a whirlpool effect. To prevent this, many spa main drains are fitted with anti-vortex drain covers which are slightly dome-shaped with the openings located around the sides of the dome.

Obviously in a pool where the main drain is very deep, this is not a concern, so safety suction lines are not added. Also, the suction in a pool is usually divided between the main drain and the skimmer, so one is not dangerously stronger than the other. Pool main drain covers are flat with the openings on top. The drain area is covered by a grate, usually 8 to 12 inches in diameter that screws or twist-locks into a ring that has been plastered into the pool bottom.

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Plumbing Guidelines

Before proceeding to specific instructions on working with PVC plastic, galvanized, or copper plumbing, here are a few general guidelines that should be taken into consideration, regardless of the material you are using.

Measure the pipe run carefully, particularly if you are repairing a section between plumbing that is already in place. In measuring, remember to include the amount of pipe that fits inside the connection fitting, usually about 1-1/2 inches at each joint.

When working on in-place plumbing, support your work by building up wood or bricks under the pipe on each side of your work area. This prevents vibration as you cut, which can damage pipes or joints further down the line. Also, unsupported pipe sags and binds when you cut it. That is, as you cut, it pinches the saw blade making cutting difficult.

Threaded fittings are obvious and simple; however to prevent leaks from occurring in these connections, carefully cover the male threads with PTFE tape and tighten the fitting as far as possible without cracking. PTFE tape fills the gaps between the threads and prevent leaking. Apply the tape over each thread twice, pulling it tight as you go so you can see the threads. Apply the tape clockwise as you face the open end of the male threaded fitting. If you apply the tape backwards, when you screw on the female fitting, the tape will skid off the joint.

Another method of sealing threads is to apply joint stick or pipe dope. Joint stick is a stick of a gum-like substance that works like PTFE tape. Rub the joint stick over the threads so that the gum fills the threads. Apply pipe dope the same way. The only difference is that dope comes in a can with a brush and is slightly more fluid than joint stick. The key to success with joint stick or pipe dope is to apply it liberally and around all sides of the male threaded fitting, so that you have even coverage when you finally screw the fittings together. Some product will ooze out as you tighten the fittings together, but that proves that you have applied enough. If you use dope or stick, be sure it is a non-petroleum-based material. Petroleum-based products will dissolve plastic over time, creating leaks.

A hacksaw or a pipe cutter can be used for cutting the pipes. Pipe cutters are adjustable wrench-like devices that have cutting wheels and are made for cutting PVC or metal pipes. You lock the device around the pipe and rotate it, constantly tightening it as you go, until the pipe is cut. They provide the straightest, cleanest cut of all. A hacksaw can do the work faster if it has fresh blade attached to it.

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PVC Plumbing

Pool plumbing is prepared with plastic or metal lengths of pipe and connection fittings that join those lengths together. The pipe acts as the male which fits and is glued into the female openings of these connection fittings. Alternatively, connection is made by each side having threads, joined by screwing them together. The plastic pipe used is PVC (polyvinyl chloride) and it is manufactured in a variety of different strengths depending on the intended use.

To help identify the relative strength of PVC, it is labeled by a schedule number; the higher the number, the heavier and stronger the pipe. Pool plumbing is done with PVC schedule 40.

PVC is designed to carry unheated water (under 100 degrees F). CPVC is formulated to withstand higher temperatures for connection close to a pool or spa heater.

All pipe is measured by its diameter, expressed in inches. Typically pool plumbing is done with 1/2- or 2-inch pipe, referring to the interior diameter (the diameter of the pipe that is in actual contact with the water). The exterior diameter of the pipe is more related to the wall thickness depending on the material.

All pipe is connected with fittings. Fittings that allow connection of pipe along a straight run are called couplings, at right angles are called 90-degree couplings or elbows, 45-degree angles, T fittings, and a variety of other formats. In the case of PVC, such fittings are most often smooth-fitted and glued together called slip fittings.

Some fittings are threaded (called threaded fittings) with a standard plumbing thread size so they can be screwed into comparable connecting fittings in pumps or other plumbing parts. National Pipe Thread (NPT) standards are used in the United States so different products of various materials by different manufacturers will all work together. The NPT standard includes a slight tapering between the male and female connections. The importance of this is that because of this taper, it is easy to over tighten plastic threaded fittings and crack them. Great Britain, Europe, and Asia not only operate on metric measurements, but also have their own unique thread standards. Fittings with male (external) threads are called mip and fittings with female (internal) threads are called fip. If one side of the fitting is mip and one side is slip, you order it as mip by slip, and so on.

In most cases with pool and spa plumbing, the long runs of pipe will be underground. Sometimes, however, horizontal runs will be under a house or deck or over a slope where support is needed. in this case, pipe should be supported every 6 to 8 feet, hung with plumber's tape to joists or supported with wooden bracing. PVC does not require support on vertical runs because of its stiffness, but common sense and local building codes might require strapping it to walls or vertical beams to keep it from shifting or falling over. Remember, the pipe becomes considerably heavier when it is filled with water and might vibrate along with pump vibration.

Supplies

The supplies and tools you need for PVC plumbing are: Hacksaw with spare blades (coarse: 12-18 teeth per inch); PVC glue and primer; Cleanup rags; Fine sandpaper; PTFE tape or joint stick.

Plumbing Methods

The concept of joining PVC pipe involves welding the material together by using glue that actually melts the plastic parts to each other. In truth, each joint will have an area that is slightly tighter than the rest. In the tightest parts, this welding actually occurs. In the remainder, the glue bonds to each surface and itself becomes the bonding agent. Obviously the strongest part of each joint is the welded portion; but in either case, the key is to use enough glue to ensure total coverage of the surfaces to be joined.

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Following is the correct procedure for plumbing with PVC:

• Cut and dry fit all joints and plumbing planned. Dry fitting ensures the job is right before gluing. If you need the fitting and pipe to line up exactly for alignment with other parts, make a line on the fitting and pipe, with a marker when dry fitting so you have a reference when you glue them together.

• Lightly sand the pipe and inside the fittings so they are free of burrs. The slightly rough surface will also help the glue adhere better.

• Apply a preparation material, called primer, to the areas to be joined before gluing. Some PVC glues are solvent/glue combinations and no primer is required. In some states, however, use of primer might be required by building code, so check that before selecting an all-in-one product. If you are using primer, apply it with the swab provided to both the pipe and the inside of the fitting. Read and follow the directions on the can.

• Before gluing, be ready to fit the components together quickly because PVC glue sets up in 5 to 10 seconds. Apply glue to the pipe and inside of the fitting.

• Fit the pipe and fitting together, duplicating your dry fit, and twist about a half turn to help distribute the glue evenly, realigning the lines drawn on the pipe and on the fitting. If using flexible PVC, because it is made by coiling a thin piece of material and bonding it together, do not twist it clockwise. This can make the material swell and push the pipe out of the fitting.

• With rigid PVC, hold the joint together about a minute to ensure a tight fit; about two minutes with flex PVC. Although the joint will hold the required working pressure in a few minutes, allow overnight drying before running water through the pipe to be sure.

Tips

• Make all threaded connections first, so if you crack one while tightening it can be easily removed. Then glue the remaining joints to the threaded work.

• When cutting PVC pipe, hacksaw blades of 12 teeth per inch are best, particularly if the pipe is wet (as when making an on-site repair). Finer blades will clog with soggy, plastic particles and stop cutting. In all cases, the key is a fresh, sharp blade. For the few pennies involved, change blades in your saw frequently rather than hacking away with dull blades-you'll notice the difference immediately.

• No matter how careful you are, you will drip some glue on the area or yourself. Always carry a supply of dry, clean rags to keep the work area clean of glue.

• Try to make as many free joints as possible first. By that I mean the joints that do not require an exact angle or which are not attached to equipment or existing plumbing. The free joints are those that you can easily redo if you make a mistake. Do the hard ones last-those that commit your work to the equipment or existing plumbing and cannot be undone without cutting out the entire thing and starting over.

• Use as much glue as you need to be sure there is enough in the joint. It's easier to wipe off excess glue than to discover that a small portion of the joint has no glue and leaks.

• Flexible PVC is the same as rigid, but when you insert the pipe into a fitting, hold it in place for a minute or longer because flex PVC has a habit of backing out somewhat, causing leaks.

• In cold weather, more time is required to obtain a pressure-tight joint, so be patient and hold each joint together longer before going on to the next.

• Bring extra fittings and pipe to each job site. Bring extras of the types you expect to use, as well as types you don't expect to use, because you just might need them. Bring extra glue, sandpaper, and rags too.