TYPES OF WELL PUMPS

When working with potable water supplies there are four main types of pumps that you may encounter:

• ¦ Submersible pumps
• ¦ Shallow-well jet pumps
• ¦ Deepwater jet pumps
• ¦ Booster pumps

The type of pump selected is often determined by the type of well used to obtain water.

BOOSTER PUMPS

Booster pumps are used in conjunction with other pumps when additional water pressure is required. A booster pump is not a primary well pump.

We will discuss these pumps in Section 3, as we explore the requirements for pump sizing and meeting low demands. This section concentrates on the three main types of primary well pumps and the basics of when to use them.

SIMPLE PUMP CHOICES

There are some simple pump choices to consider. We will examine the more technical elements of pump selection in Section 3. For now, let's look at some of the obvious pros and cons, along with some restrictions that may apply.

Assume that you are working with a bored well that has a depth of 38 feet. You need to lift water approximately 30 feet to meet the demands of the plumbing design. Which type of pump would you use? In this situation you could install a submersible pump, a one-pipe jet pump, or a two-pipe jet pump. The lift requirement on the pump is low enough that any of these pumps will get the job done.

Now consider a situation where you have a drilled well with a depth of 75 feet. Which types of pumps can be used to deliver water from this well? A shallow-well jet pump won’t work. fit is not capable of lifting water from such a depth. You can use a deep-well jet pump with a two pipe system or you can install a submersible pump. In most cases the sensible choice will be a submersible pump.

SHALLOW-WELL JET PUMPS

Shallow-well jet pumps are limited in their abilities. These pumps work on a suction basis. When water is at sea level a shallow-water jet pump can lift fit a maximum of just under 34 feet under ideal conditions. Since conditions are rarely ideal, fit is a good idea to factor in some loss in water lift. For example, I would not expect a shallow-well jet pump to lift water more than about 30 feet. Pump manufacturers generally suggest that a maximum amount of lift should be figured at 25 feet and that you should deduct 1 foot of lift for every 1000 feet of elevation above sea level. Section 3 provides more of this type of information in discussions on pump selection and sizing.

DEEP-WELL JET PUMPS

Deep-well jet pumps rely on a two-pipe system in the well casing. The pump pushes pressure down one pipe to bring fit up the other pipe. This arrangement is suitable for wells that are up to 120 feet deep. However, I recommend limiting this use to a depth of 100 feet.

Deep-well jet pumps are also called convertible pumps. This is because they can be used as either one-pipe shallow-well pumps or two pipe deep-well pumps. The piping arrangement makes the difference.

Section 9 goes into greater detail about this.

SUBMERSIBLE PUMPS

A submersible pumps is the king of deep wells. This pump is installed in the well casing, near the bottom of the well. The downside is servicing the pump. In order to work on a submersible pump you must first remove fit from the well, which means removing the piping and electrical wiring that is connected to the pump. This can be done by hand if you have a strong back, but a mechanical pump pulling machine makes the process far easier and much quicker.

Jet pumps are installed above ground. This makes them easier to access when service is required. But submersible pumps are more efficient when lifting water from deep wells. Unlike deep-well jet pumps, submersible pumps are not restricted to certain depths. They push water up the supply pipe, and as long as the pumps are powerful enough to push water the needed distance, they can be used.

A RULE OF THUMB

As a rule of thumb, you can use a single-pipe jet pump when water has to be lifted 25 to 30 feet. Once that amount of lift is exceeded, a two-pipe jet pump can be used for a depth of 100 to 120 feet. Beyond that, a submersible pump is needed.

COST

The cost of a pump goes up as fits pumping power increases. Shallow well jet pumps are the least expensive option. Deep-well jet pumps are next in line, with submersible pumps being the most expensive design to buy. This is probably the main reason that some people use deep-well jet pumps instead of submersible pumps if the well depth allows for such a choice.

Most plumbers and well installers agree that submersible pumps are better than deep-well jet pumps and should be used in all applications other than shallow wells. But sometimes money is a factor at the time of installation, so fit is good to be aware of all of your options.