Pump is completely silent
No vibration, no motor sound, and the pipe near the pump does not warm up when the system should be running.
Start here: Start with power, timer settings, switched outlets, and any control that tells the pump when to run.
Hot water circulation problem
Water Heater Recirculation Pump Not Working
Direct answer: When a water heater recirculation pump stops working, the usual causes are lost power, a timer or aquastat setting issue, a closed valve, air trapped in the loop, or a pump motor that hums but no longer moves water.
Most likely: Start by confirming the pump actually has power and is supposed to be running right now. A lot of "bad pump" calls turn out to be an off timer, a tripped outlet, or an isolation valve left closed after service.
A working recirculation setup usually gives you a simple clue: the return line warms up and hot water gets to the far fixture faster than usual. If that stopped all at once, stay with the easy checks first. Reality check: some systems only run on a schedule, so a quiet pump in the middle of the day is not automatically failed. Common wrong move: replacing the pump when the real problem is a timer, closed valve, or a stuck check valve in the loop.
Don’t start with: Do not start by buying a replacement pump or opening electrical covers. First figure out whether the pump is dead, just not being told to run, or running without circulation.
Pump silent at timesCheck the outlet, switch, timer, and any call-for-circulation control before assuming the motor failed.
Pump hums but no hot water movesLook for a stuck rotor, trapped air, closed valve, or a check valve that is blocking flow.
Last reviewed: 2026-04-05
What the failure looks like
Pump hums or feels warm
You can hear a low hum or feel the motor body warming up, but hot water still does not reach fixtures quickly.
Start here: Check for a stuck rotor, closed isolation valve, trapped air, or a blocked check valve.
System worked after install but quit after service
The problem started after the water heater was flushed, replaced, or nearby plumbing was shut off.
Start here: Look for valves left closed, air in the loop, or wiring and timer settings that were not restored.
Only the far fixture is slow now
Nearby fixtures still get hot fairly quickly, but the longest run acts like the recirculation loop is not helping.
Start here: Check whether the return line is warming at all and whether a crossover or check valve in the loop is stuck.
Most likely causes
1. Power or control issue to the recirculation pump
This is the most common clean failure. The pump stays silent because the outlet, switch, timer, aquastat, or plug connection is off or interrupted.
Quick check: Verify the pump is plugged in firmly, the receptacle has power, and the timer or control is actually calling for circulation right now.
2. Isolation valve or check valve problem in the recirculation loop
A valve left closed or a stuck check valve will make the system act dead even if the pump motor is running.
Quick check: Follow the piping at the pump and return line. Make sure service valves are open and look for a check valve body that stays cool while the pump hums.
3. Air trapped in the recirculation line
After draining or plumbing work, air can stop circulation or make the pump cavitate instead of moving water.
Quick check: If the problem started right after service and the pump sounds different than usual, suspect air before you condemn the motor.
4. Failed or seized water heater recirculation pump motor
Older pumps can seize, hum without turning, leak at the body, or stop completely after years of heat and mineral exposure.
Quick check: If power is present, controls are calling, valves are open, and the pump still will not circulate, the pump itself moves to the top of the list.
Step-by-step fix
Step 1: Make sure the pump is supposed to be running right now
Recirculation systems are often controlled by a timer, temperature control, button, motion sensor, or smart outlet. If the control is off, the pump can look failed when it is just idle.
- Find the recirculation pump near the water heater and look for a plug, switch, timer, or small control box tied to it.
- Check whether the pump is on a schedule. If it has a timer, confirm the current time and the on-periods are set correctly.
- If the system uses a demand button or sensor, trigger it and listen for the pump to start within a few seconds.
- Make sure the pump plug is fully seated and any nearby service switch is on.
- If the pump is plugged into a GFCI receptacle, check whether that receptacle or an upstream GFCI has tripped.
Next move: If the pump starts after correcting the control or restoring power, let it run a few minutes and test the far fixture again. If the pump is still silent or only hums, move on to the piping and circulation checks.
What to conclude: A silent pump with no call for circulation is usually a control or power issue, not a failed pump.
Stop if:
- You find burned wiring, melted insulation, or a scorched plug.
- Resetting a tripped outlet immediately trips it again.
- The pump or nearby piping is leaking onto electrical parts.
Step 2: Check the easy plumbing-side blockers
A recirculation pump cannot move water through a closed valve, and this is common after maintenance or water heater replacement.
- Look for isolation valves on both sides of the recirculation pump and on the return line near the water heater.
- Confirm lever handles are parallel with the pipe when open. If you have wheel-style valves, make sure they are backed open and not left shut.
- Feel the pipe on both sides of the pump after the system has had a chance to run. A sharp temperature difference across a closed point is a clue.
- If you can identify a check valve in the loop, note whether the pipe before it gets warm while the pipe after it stays cool.
- At the farthest hot-water fixture, run hot water and see whether the return line near the heater begins warming after a short delay.
Next move: If opening a valve restores circulation, leave the system running and recheck hot-water delivery at the far fixture. If valves are open and the return line still stays cool, the problem is likely air, a stuck check valve, or the pump itself.
What to conclude: A running pump with no temperature change in the loop usually means flow is blocked or never starts.
Step 3: Separate trapped air from a bad pump
Air in the loop is a common lookalike after draining the tank or opening nearby plumbing. The pump may run but not actually circulate.
- Think back to when the problem started. If it began right after flushing, replacing, or draining the water heater, air is more likely than sudden pump failure.
- Listen closely at the pump while it is energized. Gurgling, light rattling, or a dry whir can point to air instead of a dead motor.
- Open the farthest hot-water fixture and let it run long enough to purge obvious air from the hot side, then trigger the recirculation system again if it is demand-controlled.
- Check whether the return line gradually warms after purging. You are looking for any sign that flow has restarted.
- If the system has a service procedure from the installer for purging the recirculation loop, follow that procedure only if it does not require live electrical work or opening sealed controls.
Next move: If circulation returns after purging and the return line warms normally, air was likely the issue. If there is still no flow and the pump hums or gets hot, suspect a seized pump or a stuck check valve.
Step 4: Decide whether the pump motor is actually failed
Once power, controls, and obvious flow blockers are ruled out, the pump itself becomes the likely fault. The key is the difference between dead silent, humming, and leaking.
- With the system calling for circulation, place a hand on the pump body carefully. A healthy running pump usually has a light steady vibration.
- If the pump is energized but only hums, the rotor may be seized even though the motor is trying to start.
- Look for water staining, mineral crust, or active seepage at the pump body or flange area. Leakage often means the pump is at the end of its life.
- If the pump is completely silent after you confirmed power and controls, the motor windings or internal electronics may have failed.
- If the pump runs and vibrates but the return line never warms, a stuck water heater recirculation check valve is still in play.
Next move: If your checks clearly point to a failed pump, plan a pump replacement with the exact voltage, connection style, and flow direction matched to the existing unit. If you cannot confirm whether the pump is energized safely, stop here and have a plumber or electrician test it.
Step 5: Finish with the right repair path
At this point you should know whether you fixed a control issue, reopened a valve, cleared air, or narrowed it to a failed pump or check valve.
- If the problem was a timer, outlet, switch, or simple setting, restore the schedule and verify hot water reaches the far fixture faster again.
- If a valve was closed, leave it in the correct position and watch the system through one full heating cycle for normal circulation.
- If air was the issue, recheck the system later the same day to make sure circulation does not fade again.
- If the pump is confirmed failed, replace the water heater recirculation pump with one that matches the existing installation details exactly.
- If the pump appears to run but flow is still blocked, have the recirculation loop and check valve inspected and serviced by a plumber.
A good result: You should see the return line warm up and the far fixture get hot noticeably faster than before.
If not: If the loop still does not circulate after these checks, the problem is beyond a simple homeowner fix and needs on-site diagnosis.
What to conclude: The goal is not just a running motor. The real win is restored hot-water delivery and a warming return line.
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FAQ
How do I know if my water heater recirculation pump is bad?
If the pump has power and is supposed to be running but stays silent, only hums, leaks, or never warms the return line, the pump is a strong suspect. If it runs smoothly but water still does not circulate, look hard at valves, air, or a stuck check valve first.
Why is my recirculation pump running but I still wait for hot water?
That usually means the motor is turning but water is not moving through the loop. The common reasons are a closed isolation valve, trapped air, a stuck check valve, or a crossover issue in the recirculation setup.
Can air in the line stop a recirculation pump from working?
Yes. After draining or servicing the water heater or nearby plumbing, air can keep the pump from moving water normally. A dry whir, gurgling sound, or a problem that started right after service all point that way.
Should a recirculation pump run all the time?
Not always. Many systems run only on a timer, temperature control, occupancy sensor, or push-button demand control. Check how your system is meant to operate before deciding the pump has failed.
What if my water heater also is not making hot water?
Then the recirculation pump may not be the main problem. If the heater itself is not producing hot water, use the correct no-hot-water diagnosis for your heater type first. A recirculation pump cannot deliver heat the water heater is not making.
Can I replace a recirculation pump myself?
Some homeowners can, but fitment and isolation details matter, and mistakes can cause leaks or electrical trouble. If you cannot safely isolate the pump, match the replacement exactly, and restore the system without leaks, call a plumber.