A sump pump humming but not pumping due to an air lock is a common issue that can lead to basement flooding. This problem occurs when air becomes trapped in the pump system, preventing water from being expelled. Understanding the causes and solutions for this issue is crucial for maintaining a dry basement and preventing water damage.
What Causes a Sump Pump to Hum Without Pumping?
The primary causes of a sump pump humming without pumping include:
- Air lock in the system
- Clogged or blocked impellers
- Faulty check valve
- Motor malfunction
- Damaged or worn out bearings
Let’s focus on the air lock issue, which is often the culprit when a sump pump hums but doesn’t pump water.
How Does an Air Lock Occur in a Sump Pump?
An air lock in a sump pump system typically happens due to:
- Lack of a relief hole in the discharge pipe
- Plugged relief hole
- Improper check valve installation
When air gets trapped between the pump and the check valve, it creates a vacuum that prevents water from flowing through the system. This results in the pump motor humming as it tries to move water, but no actual pumping occurs.
What Are the Signs of an Air Locked Sump Pump?
Identifying an air locked sump pump is crucial for prompt resolution. Here are the key signs:
- Humming sound from the pump
- No water discharge despite the pump running
- Rising water level in the sump pit
- Pump feels warm to the touch due to continuous running
How Can You Troubleshoot an Air Locked Sump Pump?
Follow these steps to troubleshoot and potentially resolve an air locked sump pump:
- Check for a relief hole in the discharge pipe
- Inspect the check valve for proper installation and function
- Clear any debris from the pump and pit
- Verify power supply stability
What Is the Importance of a Relief Hole?
A relief hole plays a crucial role in preventing air locks:
- Allows trapped air to escape
- Typically 1/16 to 1/8 inch in diameter
- Located between the pump and check valve
- Drilled at a downward angle
Without this small but essential feature, air can easily become trapped in the system, leading to the humming issue.
How Do You Fix a Sump Pump Air Lock?
To resolve an air lock in your sump pump system, consider these solutions:
Solution 1: Drill a Relief Hole
| Step | Action | Tools Required |
|---|---|---|
| 1 | Locate the discharge pipe between pump and check valve | None |
| 2 | Mark the spot for the hole | Marker |
| 3 | Drill a 1/16 to 1/8 inch hole at a downward angle | Drill with appropriate bit |
| 4 | Clean any debris from the new hole | Small brush or compressed air |
Estimated Cost: Minimal (if you have a drill)
Effectiveness: Highly effective in resolving air lock issues
Solution 2: Replace the Check Valve
- Turn off the pump and unplug it
- Loosen the radiator clamps holding the check valve
- Remove the old valve
- Install the new check valve, ensuring correct orientation
- Tighten the radiator clamps
- Plug in the pump and test
Estimated Cost: $10 to $50 for a new check valve
Effectiveness: Very effective if the old valve was malfunctioning
What Other Factors Can Cause a Sump Pump to Hum Without Pumping?
While air locks are a common cause, other factors can lead to a humming sump pump that doesn’t pump:
- Motor Malfunction
- Signs: Unusual noise, inconsistent operation
-
Solution: Motor replacement may be necessary
-
Clogged Impellers
- Signs: Humming due to debris accumulation
-
Solution: Regular cleaning of the sump pit and impellers
-
Damaged Bearings
- Signs: Loud humming noise
- Solution: Lubrication or replacement of bearings
How Can You Prevent Future Air Locks in Your Sump Pump?
Preventing air locks is key to maintaining a properly functioning sump pump:
- Ensure a relief hole is present and clear
- Regularly clean the sump pit and pump
- Check and maintain the check valve
- Consider installing a pump with larger intake size (1/2 inch or more)
- Monitor power supply stability
By following these preventive measures, you can significantly reduce the likelihood of air locks and other issues that cause your sump pump to hum without pumping.
When Should You Call a Professional?
If you’ve tried the above solutions and your sump pump is still humming without pumping, it may be time to call a professional. Consider contacting a plumber or pump specialist if:
- You’re uncomfortable performing DIY repairs
- The pump continues to malfunction after troubleshooting
- There are signs of electrical issues
- The pump is old and may need replacement
A professional can diagnose complex issues and ensure your sump pump system is functioning correctly to protect your home from water damage.
Remember, regular maintenance and prompt attention to issues like air locks can extend the life of your sump pump and prevent costly water damage to your basement or crawl space.
References:
1. Jolly Plumbing – Reasons Why Your Sump Pump Is Humming
2. Fenwick Home Services – Why Is My Sump Pump Making A Humming Noise?
3. RooterPLUS – Troubleshooting Your Sump Pump Noise
4. Sump Pump Guru – How to Fix an Airlock in a Sump Pump
5. Plumbing Dynamics – Sump Pump Troubleshooting Guide