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What Is Air Lock in a Water Pump? Causes, Fixes & Prevention
Airlocks in pumps • Jet pump airlock • Shower pump airlock • Borehole pump airlock • Boiler airlock • Pipe airlock removal • Pump troubleshooting
Air lock is one of the most common reasons a water pump stops pumping water, runs dry, or loses pressure. Whether you have a jet pump, borehole pump, shower pump, booster pump, or boiler system, airlock can interrupt the flow and cause serious damage if not solved quickly.
This expert guide explains:
1. What Is an Air Lock in a Water Pump?
An air lock occurs when air bubbles get trapped inside the pump or pipes, blocking water flow. Because pumps are designed to move water—not air, the trapped air prevents the pump from creating enough suction or pressure.
Symptoms of Air Lock
Pump runs but no water comes out
Weak water pressure
Sputtering or irregular flow
Pump keeps priming itself
Pump overheats
Sudden stop after running normally
When air displaces water inside the pump, the motor runs dry, leading to pump damage, overheating, and burnt impellers.
2. What Causes Air Lock in a Water Pump?
Air lock can happen in any water pump system. The main causes include:
2.1 Low Water Levels
If the water source (well, tank, borehole) drops below the pump inlet, air gets sucked in.
2.2 Leaks in Suction Line
Even tiny leaks allow air to enter the pipe.
2.3 Poor Pump Priming
If the pump was not completely filled with water during installation or restart.
2.4 High Points in Piping
If pipes rise at certain angles, air gathers at the top and blocks flow.
2.5 Recently Drained Tanks or Boreholes
When tanks or boreholes are cleaned, pipelines refill with air.
2.6 Faulty Foot Valve / Non-Return Valve
A worn-out valve allows air to flow backward into the suction line.
2.7 Pump Installed Above Water Level
Creates natural vacuum spaces where air collects.
2.8 Hot Water Systems (Boilers)
Heat creates steam pockets that turn into airlocks in pipes.
3. What Is the Purpose of an Air Lock?
There is no intentional purpose for an air lock—it is not a feature, but a problem.
Some people confuse it with:
“Air chamber”
“Pressure tank”
These are designed features.
Air lock is accidental and harmful.
4. Most Effective Ways to Remove Air Lock in a Water Pump
The exact method depends on your pump type, but here are the universal solutions:
4.1 Method 1: Manual Priming (Most Common Fix)
Turn off the pump.
Open the priming plug.
Fill the pump completely with water.
Close the plug.
Restart the pump.
If water starts flowing immediately, the airlock is cleared.
4.2 Method 2: Force Water Through the System
Useful for long pipelines and borehole pumps.
Connect a hose from a pressurized water source (tap) to the pump outlet.
Push water backwards through the pipes.
Air escapes through the suction side.
4.3 Method 3: Bleed Valves (For Shower Pumps)
Shower pumps usually have bleed screws:
Loosen the screw with pump off.
Let trapped air escape.
Close once water appears.
4.4 Method 4: Siphon Method (Jet Pumps & Booster Pumps)
Fill both suction and discharge lines with water to create a full water column.
4.5 Method 5: Forcing the Pump to Cycle
Turn pump ON and OFF rapidly to shake out trapped air.
(Not recommended for long periods—can damage pump.)
5. Airlocks in Shower Pumps – Causes, Fixes & Prevention
Shower pumps are extremely prone to air lock because they use low-pressure lines.
Causes
Hot water expansion
Tank refilling
Negative pipe gradient
Air in mixer taps
Blocked filters
Fix
Bleed the pump
Prime the suction pipe
Lower the pump relative to the tank
Clean filters
Prevention
Keep tanks always above pump level
Avoid sharp pipe bends
Install anti-airlock valves
6. How To Remove Airlock in Jet Pumps
Jet pumps lose prime easily.
How to fix a jet pump airlock
Fill pump casing with water
Fill suction pipe
Replace priming cap
Check for suction leaks
Ensure foot valve is not stuck
This fully restores suction.
7. Boiler Airlock Causes & How To Fix an Airlock in Pipes
Boilers create airlocks when:
Hot water expands into steam
Radiators trap air
Pump pressure drops
Fix
Bleed radiators
Bleed boiler pump
Open highest faucets to release air
Check boiler pressure (should be 1–2 bar)
8. How Do You Get Rid of an Airlock in a Water Pump? (Quick Summary)
Prime the pump
Bleed air valves
Pressurize the lines
Repair pipe leaks
Replace faulty foot valve
Adjust installation height
Ensure water source is steady
9. How to Prevent Air Lock Permanently
Install foot valve or NRV
Remove high spots in pipes
Use a constant water level
Seal all suction leaks
Keep pump below water level
Maintain full water column
10. Frequently Asked Questions (FAQ)
1. What are the signs of air lock in a pump?
No water, weak pressure, sputtering water, pump running dry, or overheating.
2. Will air lock damage my pump?
Yes.
It causes overheating, impeller wear, dry-running, and motor burnout.
3. How do I remove air lock from pipes in a house?
Open all taps, especially the highest one, until air escapes.
4. Why does my shower pump stop after a few seconds?
Air lock or blocked filters.
5. Can borehole pumps get air lock?
Yes — especially shallow wells with dropping water levels.
6. Does hot water create more airlocks?
Yes — heat creates steam pockets.
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Air lock is a common problem across water pumps, jet pumps, shower pumps, booster pumps, borehole pumps, and boiler systems. Proper priming, sealing, bleeding, and installation prevent future issues.
If your system keeps getting air lock, contact:
Moffam Electricals
Professional Water Pump Technicians
Airlock removal
Pump repairs
Borehole pump diagnostics
Shower pump repair
Boiler airlock clearing
Pipe bleeding & priming
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