A well pump with a pressure tank works by using a pump to move water from the well into the tank, which then stores the water under pressure provided by compressed air, allowing for on-demand water supply without the pump constantly cycling on and off.
Here's a breakdown of the process:
1. The Well Pump
- A submersible well pump (typically) located down in the well draws water upwards.
- This pump is activated by a pressure switch connected to the pressure tank.
2. The Pressure Tank
- The pressure tank is a reservoir that holds water under pressure. It's crucial for consistent water supply and preventing the pump from running constantly.
- Air Compression: The tank contains a bladder or diaphragm that separates the water from compressed air. As water enters the tank, it compresses the air. Because air is compressible and water is not, this compression builds pressure in the tank.
- Pressure Regulation: The pressure switch monitors the pressure within the tank.
3. The Cycle of Operation
- Pump Start: When a faucet is opened or water is used, the pressure in the tank drops.
- Pressure Switch Activation: Once the pressure drops to a pre-set "cut-in" pressure (e.g., 40 PSI), the pressure switch signals the well pump to turn on.
- Tank Filling: The pump draws water from the well and forces it into the tank, further compressing the air.
- Pump Stop: The pump continues to run until the pressure in the tank reaches a pre-set "cut-out" pressure (e.g., 60 PSI). The pressure switch then shuts off the pump.
- Water Delivery: When you use water, the compressed air in the tank forces the water out through your plumbing. This provides water at a consistent pressure without immediately activating the pump.
- Repeat: This cycle repeats as water is used and the pressure in the tank drops again.
4. Why is a Pressure Tank Important?
- Consistent Water Pressure: Provides a steady flow of water, even when multiple fixtures are in use.
- Extends Pump Life: Reduces the number of times the pump has to start and stop, which prolongs its lifespan. Starting and stopping a motor is more stressful on it than running it continuously.
- Energy Savings: Prevents the pump from running constantly, saving energy.
- Water Storage: Provides a small reserve of water in case of a power outage.
5. Common Pressure Settings
| Setting | Example Value (PSI) | Description |
|---|---|---|
| Cut-in Pressure | 40 | The pressure at which the pump turns ON. |
| Cut-out Pressure | 60 | The pressure at which the pump turns OFF. |
| Differential | 20 | The difference between the cut-in and cut-out pressure. |
It's important to note that these are just example values, and the actual settings may vary depending on the well pump system and household needs. It's recommended to consult with a qualified plumber or well technician for proper pressure settings.
In essence, a well pump with a pressure tank is a system designed to efficiently deliver water from a well, maintain consistent pressure, and extend the life of the well pump itself. The key is the pressure tank's ability to store water under air pressure.
