You can have constant pressure on your private water well system … just like city water. The pump controller converts single phase 230 volt power to three phase 230 volt power. It varies the frequency to control the speed of the pump. This allows the pump to turn at the speed necessary to provide constant pressure.
As flow demand changes, the motor speed changes to maintain a constant pressure. Standard systems vary the pressure by 20 psi while this system allows a variance of only 2 psi. There are different models of controllers for each type of pump. In some cases, the constant pressure system is less expensive than the standard system.
A typical constant pressure water well system (with a pitless adaptor/Hide-a-well wellhead) looks like the diagram below. The submersible pump pushes water up through the drop pipe to the surface. The check valve keeps water from flowing back into the well. When the pressure in the system drops by 5 psi, a pressure sensor tells the pump controller to turn on the pump.
Then, as described above, the controller varies the speed of the pump to maintain the pressure to within 2 psi of your desired setting (under most conditions). The pressure is stored in a small pressure tank – typically 20 gallons (as opposed to an 84 gallon tank or larger for a basic/standard system). The pump controller is programmed to recognize a variety of conditions that might damage the pump and to temporarily shut off the pump in those situations.
Should the pump controller fail to monitor the pressure and the system builds too much pressure, the relief valve will release the excess pressure.
This system is great for those homeowners who want the assurance of full pressure throughout their showers. It is also beneficial for reverse osmosis (RO) systems. The most common usage of these constant pressure systems is for irrigation. When the pressure varies in the basic/standard system, so does the distance that your sprinkler heads throw the water.
As a result you can get dry/brown patches in your lawn. With the constant pressure system, your sprinklers will throw the same distance every time. Another advantage to the constant pressure system is that as long as there is at least a 1 gpm water demand, your pump stays on. With a basic/standard system your pump could cycle on and off hundreds of times during an irrigation cycle. This can shorten the life of your pump by 2-3 years.
Another advantage to the constant pressure system is that when the pump does start/stop, it does so gradually. This too can lengthen the life of your pump.
The constant pressure system does have its drawbacks, however. The computerized pump controller (a variable frequency drive – or VFD) can sometimes be finicky if it does not have a “clean” power source. So they are best for in-town use. Also this controller will wear out in about 10 years or so and cost a few thousand dollars to replace.
Click here to go to the Basic/Standard Water Well System page. Click here for a video comparing and contrasting a Basic vs. Constant Pressure water well system. Click here for information on incorporating a Storage Tank System into your Constant Pressure Well System.