WELL PRESSURE TANKS

How much do you know about well pressure tanks? I have been a master plumber for more than 30 years. During those years I have worked with a lot of plumbers, well drillers, and well pump installers. fit has always surprised me how little some of these professionals know about pressure tanks. A lot of the pros pay scant attention to the pressure tanks. They know they are needed and they know how to install them, but fit is a shame how many of them don’t understand the importance of proper sizing considerations.

Pressure tanks are essential to the proper operation of a well system.

There are four basic types of tanks in common use to choose from:

• In-line models (see Fgr. 1)
• Stand models (see Fgr. 2)
• Underground models (see Fgr. 3)
• Pump stand models (see Fgr. 4)

All pressure tanks have maximum operating limitations. This includes the operating temperature and the working pressure. See Tbl. 1 for an example of one manufacturer's ratings for maximum operation conditions.

Fgr. 1 In-Line Models

Fgr. 2 Stand Models

Fgr. 3 Underground Models

1 System Connection: Stainless Steel Coupling.

Coating on underground models is an epoxy-based paint.

Working Pressure: 125 PSIG (862 kPa)

Fgr. 4 Pump Stand Models

1 System Connection: Stainless Steel Waterway.

Working Pressure: WX-105-PS 100 PSIG (689.5 kPa); WX-200-PS 125 PSIG (862 kPa)

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Tbl. 1 Maximum Operating Conditions. (from Amtrol, Inc.). Operating Temperature 200° F (93° C) Working Pressure Model WX 105 PS 100 PSIG (689.5 kPa) Working Pressure Models WX 200 UG Through WX-251-UG, WX-200-PS 125 PSIG (862 kPa) Complies with Low Lead Plumbing Law

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Fgr. 5 Stand Model Technical Data

Modern pressure tanks are built with an internal diaphragm. This device provides a dependable air cushion in the tank. The tanks are shipped with precharged air content. The air provided at the factory is normally installed at a rate of 38 psi, which prevents the tank from becoming waterlogged. A tank that is waterlogged puts excessive demand on a pump that will reduce the pump life. Having a waterlogged pressure tank is nearly as bad as having no pressure tank at all. See Fgr. 5 for technical data on a stand-type pressure tank from a major manufacturer.

Well pressure tanks that are not sized or working properly can shorten the life of a pump. They also deliver lower water pressure, which does not make for happy customers. Must you install a pressure tank for a water pump to supply water to a water distribution system? No, but if you don't, the system won’t be acceptable according to professional standards.

Water pumps deliver water volume. They don’t deliver much water pressure. A pressure tank installed between the pump and the water distribution system provides the desired water pressure. The pump and the pressure tank must work together to provide optimum service.

STAND MODELS

Stand models are probably the more prevalent type of well pressure tanks used in modern plumbing systems. They range in capacity from about 10 gallons to a little over 100 gallons. The average working pressure for these tanks is 125 psi. So you can choose from within a range of 10 gallons to 100 gallons. How do you make the selection? There are some simple considerations to address first.

Size can be a factor. In some installations there is not enough space available for a large pressure tank. For example, let's look at the dimensions of a 20-gallon tank and those of a 62-gallon tank.

A 20-gallon tank stands about 31 inches tall. The 62-gallon model rises to a height of about 46 inches. If you have only 36 inches of height clearance to work with, the larger tank is out. You should also consider the diameters of the two tanks. The 20-gallon tank has a diameter of about 15 inches, while the 62-gallon tank has a diameter that is close to 22 inches. Again, the amount of available space would affect your choice of tanks. Other considerations will be covered later in this section.

Stand models are popular because they are available in a range of sizes and because they support their own weight. Not all pressure tanks do this. As a master plumber, I prefer to use stand models whenever I can, and many installers share my sentiment.

IN-LINE MODELS

In-line pressure tanks have very limited holding capacity. A small model will hold only 2 gallons, and 14 gallons is about the average maximum capacity that you can find. This is not a lot of reserve water, and a pump will cycle more often than fit should when the holding capacity is this low.

So why would you use an in-line tank? As the name implies, these tanks are piped right into the water supply and water distribution piping.

They take up very little space and are usually suspended from floor joists.

When you have limited space to work with as well as limited demand on the pump, an in-line tank is a viable option. Otherwise, avoid using this type.

PUMP STAND MODELS

Pump stand pressure tanks are used in conjunction with jet pumps. This is true of both shallow-well jet pumps and deep-well jet pumps. The pres sure tank sits on the floor and has a mounting bracket built into the top of fit. This allows the jet pump to be mounted on the tank to conserve space. However, like the in-line models, capacity ranges for pump stand tanks are very limited. The most you can expect them to hold is around 14 gallons. I recommend using pressure tanks with more capacity, but these tanks are convenient and they do save space.

UNDERGROUND MODELS

Underground pressure tanks have the potential for a large holding capacity. They generally hold up to 62 gallons. Since the tanks are installed below ground, they don’t take up any room within a building.

This is a plus. However, the fact that they are buried could be an inconvenience when fit comes to servicing the system. Underground pressure tanks must be installed in a vertical position, and they must be protected from freezing.

Underground tanks are generally equipped with stainless steel couplings for connecting them to the water service. The tanks are usually coated with an epoxy-based paint. I have more than 30 years of field experience, much of fit in rural areas, and I have never encountered an underground pressure tank.

HOW DOES A DIAPHRAGM PRESSURE TANK WORK?

Generally, diaphragm pressure tanks work very well. They are quite dependable. As I mentioned earlier, these tanks come from the factory with an air charge of about 38 psi in them, which means that they are connect-and-go tanks. You don’t have to balance them because the manufacturer has already done that for you.

In the old days, pressure tanks were generally just galvanized steel tanks with an air valve installed in the top of them. An installer had to pump air into the tank before filling fit with water. Getting the right amount of air for maximum performance could be something of a trial and-error experience. When the galvanized tanks rusted and leaked, the air escaped. This allowed water to ill most, if not all, of the tank. The result was a waterlogged tank.

When a pressure tank is waterlogged fit does not regulate pressure properly. Basically, the pressure delivered to the water distribution system is no more than what the pump is providing, and that is not much. Not only is there a lack of appropriate water pressure, the pump must cut on and run every time water is called for. These starts and stops shorten the working life of the pump. Air has to be reintroduced into a waterlogged tank to return fit to working condition. With modern pres sure tanks, this is not a concern. They just work. When they don't, fit is time to replace them.

The type of well pressure tank that I install holds the water in a molded rigid polypropylene liner supported by an outer steel shell. The diaphragm is installed over the water liner. With this type of design, the water is noncorrosive.

When water is allowed to enter the tank, the water liner expands.

The diaphragm acts as a buffer that holds the liner down with the use of air pressure. There is no strain on the diaphragm, since the water pressure and the air pressure are constantly balanced. Water pres sure is controlled by a pressure switch, which we will discuss more when we consider installation methods for well pressure tanks. (See Fgr. )

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NOTE: This is an example. Not all precharge pressure is 38 psi.

Not all system pressures shut pump off at 60 psi.

A. Factory installed precharged air cushion. Pump off.

B. When pump starts to fill, water enters the reservoir. At 60

psig, system is filled. Pump shuts off.

C. When water is demanded, pressure in the air chamber forces water into the system. Pump stays off.

60 PSIG 38 PSIG 55 PSIG 55

Fgr. 6 Visual Example of Diaphragm Well Pressure Tanks

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PRESSURE TANK CAPACITY

You will need to determine the capacity that is acceptable for a well pres sure tank that you are going to install. Some customers tell the installer the size of the tank they want or are willing to pay for. If your customer is making an inappropriate decision, you should be prepared to explain why a larger pressure tank is recommended.

Your goal in sizing the pressure tank is to choose a tank that won’t strain the pump fit serves and will give the user of the plumbing system adequate water supply and pressure. You must consider several factors.

Once you know the size of the pump you will be installing, you can begin to determine the size of the pressure tank that will provide quality service. The number of times that a pump should operate during a 24-hour period is based on the horsepower rating of the pump. See Tbl. 2 for the recommended numbers of daily starts and stops for pumps of various sizes.

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Tbl. 2 Suggested Maximum Number of Pump Starts Per Day Motor Rating Single-Phase Pump Three-Phase Pump Up to ¾ horsepower (hp) 300; 300 1 hp through 5 hp 100 300 7½ hp through 30 hp 50 100

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When you know how many daily starts the pump should be expected to deliver without undue strain, you can begin to determine how large the well pressure tank will need to be. To make this assessment, you need to consider the plumbing fixtures that will be connected to the water distribution supply. You will want data on the normal daily water usage requirements, and fit is helpful to know the average low rates for different types of fixtures. See Tables 4.3, 4.4, and 4.5 For examples of this type of information.

After you have determined the estimated volume of water that will be needed in the course of a day, you can analyze fit further by anticipating peak times of usage. If you are dealing with a business, the peak usage is likely to be spread out over a period of up to 12 hours a day. There should be minimal usage when the business is closed.

For this type of situation you need to prepare for the potential of high usage for several hours at a time and then a long period of time with little usage.

In the case of a home, there will likely be heavy usage for maybe an hour each morning. Then usage normally drops while residents are at work and school. When the occupants return home, usage will goes back up. There is likely to be a spike in late afternoon. Then there may be demands for dishwashing and washing clothes in the evening. Before bed there is normally increased usage, and then the system is at rest during sleeping hours.

Sizing a pressure tank for a home generally means that you have to prepare for periodic high usage with several lulls in between. How much water would a family of four use in 30 minutes? Conversion tables like those provided here can give you a good idea of what to expect.

There is guesswork involved when estimating water usage demands.

Ideally, you should err on the side of caution in your estimates and install a pressure tank that is larger than the expectation of what will be needed.

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Tbl. 3 Sample Flow Rate Requirements for Domestic Plumbing Fixtures

Type of Domestic Fixtures | Average Flow Rate (rates given in gallons per minute (GPM) or gallons per hour (GPH)

Toilet 1.5-5 gpm with an average of 3 gpm Bathtub 3-5 gpm Shower 3-5 gpm Lavatory 3 gpm Kitchen sink 3 gpm

½-in. water hose 200 gph

¾-in. water hose 300 gph

Lawn sprinkler 120 gph

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Tbl. 4 Sample Water Usage Requirements

Type of Usage Volume

Per person per day in a home 75 gal.

Taking a shower or bath Up to 30 gal.

Filling a bathtub Up to 30 gal.

Flushing a toilet 1.5-5 gal.

Filling a lavatory 2 gal.

Domestic dishwasher per load 7 gal.

Clothes washer per load Up to 50 gal.

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Tbl. 5 Conversion Factors for Volume 1 U.S. gallon 231 cubic inches 1 U.S. gallon 3.785 liters 1 Imperial gallon 1.2 U.S. gallons 1 barrel (oil) 42 U.S. gallons 1 cubic foot 7.48 U.S. gallons

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PRE-INSTALLATION PROCESS

There is a pre-installation process that should be conducted when you pre pare to install a well pressure tank. At the start of the installation, take note of the location of the air valve. The tank should have been charged with air before fit was made available for sale. A standard factory charge will be about 38 psi, but this may be too much pressure for your installation. fit is also possible that the tank lost air pressure before you obtained fit. Therefore, you should apply an air gauge to the air valve and confirm the actual air pressure contained in the tank. You should find the charge to be within 10 percent one way or the other of the factory precharge.

Next, you need to adjust the air pressure so that fit is within an accept able range for the pressure switch that you will be installing in the well system. Ideally, the air pressure should be about 2 psi below the cut-in set ting that the pressure switch used with the tank will have. In other words, if you are using a 30/50-psi pressure switch, the cut-in pressure is 30 psi and the cut-out pressure is 50 psi. Knowing this, you want the air pressure in the tank to be established at 28 psi. In the case of a 40/60-psi pressure switch, the air pressure would be set at 38 psi. This pre-installation process is an important part of a proper installation.

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Fgr. 7 Typical Installation of an In-Line Pressure Tank WX-101 WX-102 WX-103 PRESSURE SWITCH PRESSOSTAT INTERRUPTOR DE PRESIÓN TO SYSTEM VERS LE SYSTÈME AL SISTEMA FROM WELL EN PROVENANCE DU PUITS DEL POZO

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Fgr. 8 Typical Installation of a Horizontal Pump Stand Model Pressure Tank TO SYSTEM VERS LE SYSTÈME AL SISTEMA RELIEF VALVE SOUPAPE DE DÉTENTE VÁLVULA DE ALIVIO FROM WELL EN PROVENANCE DU PUITS DEL POZO

#162 OR #163 PUMP STAND SUPPORT DE POMPE N 162 OU N 163 BASE PARA BOMBA #162 O #163 WX-103 WX-105 WX-200 SHUT-OFF VALVE SOUPAPE D'ARRÊT VALVULA DE CIERRE PUMP POMPE BOMBA PRESSURE SWITCH PRESSOSTAT INTERRUPTOR DE PRESIÓN DRAIN

ÉVACUATION DRENAJE

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Fgr. 9 Typical Installation of a Vertical Pump-Stand

Model Pressure Tank

SHUT-OFF VALVE SOUPAPE D'ARRÊT DEL POZO PERMISSIBLE PRESSURE SWITCH LOCATION EMPLACEMENT ACCEPTABLE DU PRESSOSTAT UBICACIÓN ACEPTABLE PARA EL INTERRUPTOR

DE PRESIÓN WX-201 WX-202 WX-202XL WX-203 WX-205 OR (OU) (O) DRAIN

ÉVACUATION DRENAJE PERMISSIBLE PRESSURE SWITCH LOCATION EMPLACEMENT ACCEPTABLE DU PRESSOSTAT UBICACIÓN ACEPTABLE PARA EL INTERRUPTOR DE PRESIÓN WX-250 WX-251 WX-255 WX-302 WX-350 TO SYSTEM VERS LE SYSTÈME AL SISTEMA UNION - 2 REQUIRED RACCORD UNION - 2 NÉCESSAIRES UNIONES - SE REQUIEREN 2 PUMP POMPE BOMBA

#161 OR 3165 PUMP STAND SUPPORT DE POMPE N 161 OU N 165 BASE PARA BOMBA

#161 O 165 FROM WELL EN PROVENANCE DU PUIT VÁLVULA DE CIERRE UNION RACCORD UNION UNIÓN

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MOUNTING A PRESSURE TANK

The process of mounting a pressure tank begins with positioning the tank in fits operating location. Let's look at each type of pressure tank and how they are likely to be set or mounted.

POSITIONING IN-LINE TANKS

There are different methods for positioning in-line pressure tanks. For our example, assume that the tank is being used in conjunction with a jet pump. A common way of installing the tank is to mount fit vertically on a steel pipe nipple close to the pump. Fgr. 7 shows an example of this type of positioning.

Another way to install an in-line tank is to position fit into the system between two pieces of pipe. This is normally done by placing a tee fitting on fits back in horizontal piping. The weight of the tank in this type of installation is supported by pipe hangers that are normally installed in floor joists.

The hangers extend downward and go under the piping. Any hangers used must be capable of supporting the full weight of the tank and fits contents.

MOUNTING A PUMP STAND MODEL

Mounting a pump stand pressure tank is pretty simple. Find a solid, level surface and place the tank on fit. The pump mount is on the top of the tank and allows you to mount a jet pump to fit. Fgr. 8 shows an example of this type of installation for a horizontal tank. Fgr. 9 illustrates a pump stand tank that is set vertically.

MOUNTING A VERTICAL STAND-MODEL PRESSURE TANK

Mounting a vertical stand-model pressure tank is done on a solid, level surface. The tank is sometimes mounted on raised blocks to protect fit in the event that the basement in which fit is installed floods. The tank must be fully supported. These tanks can be used with both jet pumps and submersible pumps. Fgr. 10 shows a stand model used with a jet pump, and Fgr. 11 shows a stand model used with a submersible pump.

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WX-201 WX-202 WX-202XL WX-203 WX-205 WX-250 WX-251 WX-255 WX-302 WX-350 PRESSURE SWITCH PRESSOSTAT INTERRUPTOR DE PRESIÓN RELIEF VALVE SOUPAPE DE DETANTE VÁLVULA DE ALIVIO DRAIN

ÉVACUATION DRENAJE Fgr. 10 Vertical Stand Model Working with a Jet Pump

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WX-201 WX-202 WX-202XL WX-203 WX-205 WX-250 WX-251 WX-255 WX-302 WX-350 PRESSURE SWITCH PRESSOSTAT INTERRUPTOR DE PRESIÓN RELIEF VALVE SOUPAPE DE DETANTE VÁLVULA DE ALIVIO SUBMERSIBLE PUMP POMPE SUBMERSIBLE BOMBA SUBMERSIBLE DRAIN

ÉVACUATION DRENAJE TO WELL-XTROL VERS LE WELL-XTROL AL WELL-X-TROL PRESSURE GAUGE MANOMÈTRE MANÓMETRO Fgr. 11 Vertical Stand Model Working with a Submersible Pump

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RELIEF VALVE SOUPAPE DE DÉTENTE VÁLVULA DE ALIVIO BUILDING FOUNDATION FONDATION DU BÂTIMENT CIMIENTOS DEL EDIFICIO WELL-X-TROL

"UG" ROCK FREE COARSE SAND GROS SABLE SANS PIERRE ARENA GRUESA SIN ROCAS TO HOUSE VERS LA MAISON A LA CASA PUMP POMPE BOMBA POSSIBLE PRESSURE SWITCH LOCATION EMPLACEMENT POSSIBLE DU PRESSOSTAT POSIBLE UBICACION DEL INTERRUPTOR DE PRESIÓN FROST LINE PROFONDEUR LIMITE DE GEL NIVEL DE CONGELMIENTO Fgr. 12 Typical Installation of an Underground Well Pressure Tank

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38 PSIG 38 Ippc (2.7 Kg/cm2) 38 PSIG 38 Ippc (2.7 Kg/cm2) PRESSURE SWITCH PRESSOSTAT INTERRRUPTOR DE PRESIÓN TYPICAL HEADER TO TANK PIPING COLLECTEUR TYPIQUE DE TUYAUTERIE DE RESERVOIR TUBERÍA TÍPICA DEL COLECTOR AL TANQUE DRAIN

ÉVACUATION DRENAJE PRESSURE SWITCH PRESSOSTAT INTERRUPTOR DE PRESIÓN MAIN TUYAU PRINCIPAL TUBERÍA PRINCIPAL PRESSURE GAUGE MANOMÈTRE MANÓMETRO RELIEF VALVE SOUPAPE DE DÉTENTE VÁLVULA DE ALIVIO 38 PSIG 38 Ippc (2.7 Kg/cm2) 38 PSIG 38 Ippc (2.7 Kg/cm2) TO WELL-X-TROL VERS LE WELL-X-TROL AL WELL-X-TROL DRAIN

ÉVACUATION DRENAJE UNION RACCORD UNION UNIÓN SHUT-OFF VALVE SOUPAPE D'ARRÊT VÁLVULA DE CIERRE TO SYSTEM VERS LE SYSTÈME AL SISTEMA Fgr. 13 The Manifold Installation of Water Pressure Tanks

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UNDERGROUND WELL PRESSURE TANKS

Underground well pressure tanks must be installed vertically. They must be protected from freezing. This is usually accomplished by installing the tanks below the frost line. The tanks are generally surrounded by coarse sand that is free of all rocks. See Fgr. 12 for an example of this type of installation.

MANIFOLD INSTALLATIONS

Manifold installations of multiple tanks are used when the water demands require fit. In this type of installation the volume of water on hand can be increased substantially. Fgr. 13 shows how a manifold installation is executed.

The illustrations in this section show how pressure tanks are mounted and the normal piping arrangements.

FINE-TUNING YOUR INSTALLATION

Fine-tuning your installation is the last step in installing a pressure tank.

This takes place when the pump, electrical wiring, and all piping and fittings have been installed to connect the pressure tank to the water distribution system.

Once the pump has filled the tank with water and cut off, you should have the desired water pressure showing on the pressure gauge that serves the pressure tank. Assuming this is the case, you need to verify the cut-in and cut-out functions of the pressure switch. Open a plumbing faucet. I normally use one that ills a bathtub to avoid flooding the fixture as I move back and forth between the faucet and the pressure tank. If the pressure switch is set properly you should not notice any pause in water delivery and the water pressure should remain acceptable at all times. If there is a pause in getting water, fit is time to adjust the pressure switch.

Keep in mind that there are hot electrical wires in a pressure switch. Once you remove the protective housing that covers the switch you must be careful not to come into contact with the live wires. You will see a large spring with a nut securing the top of fit. You can control cut-in and cut-out pressure by adjusting the retaining nut and either compressing the spring or releasing tension on the spring. Turn the adjustment device clockwise if you want to increase the cut-out pres sure. If you turn the adjustment device counterclockwise you will decrease the cut-out pressure. This allows you to fine-tune the switch to provide optimum performance. See Fgr. 14 for an example of this type of pressure switch.

The installation of a pressure tank is not difficult once you understand the procedures used to select, size, mount, and plumb up the tank.

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Pressure Adjustment Clockwise To increase Cut-Out Pressure Counter Clockwise To Decrease Cut-Out Pressure Fgr. 14 Adjusting a Pressure Switch

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ADJUSTING PRECHARGE

Prior to Installation Step 1. Remove protective air valve cap Step 2. Check precharge pressure (pressure should be + or - 10% of the factory setting) Step 3. Release or add air as necessary to make the precharge pressure 2 psig below the pressure switch pump cut-in setting.

(Example, if you have a WX-202XL with a precharge of 38 psig, and you have a pressure switch setting of 30/50 psig, adjust precharge of your WX-202XL from 38 psig to 28 psig.) Step 4. Replace protective air valve cap. Peel off backing of label and apply over air valve cap.

START UP Fine Tuning Procedures Many times the actual pressure switch will vary from the standard pressure range indicated. These variations could cause a momentary lag of water delivery, as the pressure switch is not "tuned to the WELL-X-TROL precharge pressure".

1. Fill the system and WELL-X-TROL until pump cuts off.

2. Open one or more fixtures to drain the WELL-X-TROL.

3. If there is a momentary pause in the water low from the time the WELL-X-TROL is emptied and the pump starts, adjust pump cut-in setting clockwise slightly.

4. Close fixtures and refill WELL-X-TROL to pump cut off. Check time to ill.

5. Open fixtures and see if pause in water is eliminated. If not, continue adjusting pressure switch.

ADJUSTING PRECHARGE AFTER INSTALLATION Step 1. Drain tank of all water. Check precharge pressure in the WELL-X-TROL Tank.

Step 2. Release or add air as necessary to make the recharge pressure 2 psig below the pressure switch pump cut-in setting.

All WELL-X-TROL "Underground Tanks" are designed for direct burial and must be installed in the vertical position only.

To eliminate danger of freezing, tank should be buried below the frost line.

The following steps should be taken when installing WELL-X TROL "Underground Tanks":

1. Make sure that the tank will be buried below the frost line and above the water table.

2. Remove plastic bag and check tank precharge. Factory precharge is 38 psig. Replace air stem cap securely. Follow adjusting precharge procedure.

3. Important: Install tank on firm rock-free earth.

4. The Water lines from the pump to the tank and switch location should be the same size to prevent switch cycling.

5. Check the system for performance and inspect for leaks.

6. Important: Backfill hole with sand. Firmly tamp ill to prevent settling. Failure to do so will shorten tank life.

7. Fill out pressure tank location sticker and affix to power panel or other visible surface so tank can be easily located at a later time