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Circulator Pump Making Rattling Noise [Reasons & Solutions]

It’s okay to feel panicked after listening to the rattling sound coming from your circulator pump. You have to know the reasons behind it. If you do not take any action, it will cause more damage to the pump. 

Why is your circulator pump making noise?   

First, the circulator pump makes noise if it gets airlocked. Then, the pump can be over/under-sized for water flow which leads to noise. Excessive wear of bearings is also a common problem for a circulator pump. There are also more probable causes of the noise.    

Now, to fix the circulator pump, you’ll need to know more. That’s why we’ve explained each cause with their fixing process. 

Let’s fix it!

Why Is My Circulator Pump Making Rattling Noise? 

A circulator pump making rattling noise is a common problem. There are various reasons for it.

There are also solutions for every problem. First, we have to know the causes behind the noise, and how to fix them.

The Circulator Pump Is Airlocked

One of the most common reasons for rattling sounds is the airlock problem. Air gets into the system and creates malfunctioning. 

It starts to heat the pipes, resisting the bearings that create rattling sounds.


If air gets into the system, it needs to be bled out. First, you have to locate the bled screw in the pump. Carefully open it and start the pump. After the noise stops, put on the bled screw again. It will clear all the air inside the circulator pump. 

If you are using a Grundfos circulator pump, the bled screw will be at the centre of the pump.

Water Circulator Pump Is Under/Over Sized

Sometimes your water circulator pump cannot take the pressure of water. It’s because you may have a larger water heater.

You also have to check the wire size of your heater. If it doesn’t match with your heater required wire size, it creates pressure in the circulator pump which leads to a rattling sound.


To measure the correct size, let us give you an example-

If you have a 40-gallon electric water heater. The circulator pump’s capacity should be a minimum of 40 GPH (Gallon per hour).

First, you have to measure the flow rate of the water. The equation of measuring the flow rate is:

Volume units / Time units = Flow rate 

For example- 

Volume units = 40 Gallon

Time units = 1 Hour

The flow rate is, therefore, 40 / 60 = 0.6 GPH

After measuring it, compare it with your circulator’s capacity. If it doesn’t match, you have to replace the circulator pump.

Circulator Pump Installed Incorrectly   

Make sure your pump is installed horizontally. If your pump is installed vertically, air will enter the system again and again. 

You can also install a water recirculating pump yourself. If you are unable to do it, call a professional to do the job.


First, turn off the main water valve and the heater. Open up the pipes that are connected with the heater.

After removing the heater, set it horizontally. Make sure the bled screw is in the middle. You can also set your water heater horizontally if you like.

Excessive Wear Of Bearings

Some of the water circulator pumps have a bearing system in them. If your water circulator has a bearing system, it may fail. Excessive wear of bearings creates rattling noises. 

Bearings fall for various reasons. The reasons are lack of lubricants, contaminations, lack of proper mounting and misalignments etc.

So, you have to replace the bearings. 

In case you are looking for the best bearings, we have some suggestions for you-

Product 1
Product 2 

Now you have your new bearing, you can fix it. 


The first step is to turn off the main water supply. Make sure you turn off the water recirculating pump. Then open the motor with your screwdriver and wrench. Then you have to remove the impeller of the pump. After removing it, you have to remove the seal and mounting plates. 

Now, remove the motor governor. You will see the old bearing of the pump. Remove it and replace it with the new one. 

Then, set all the materials one by one. Changing the bearing requires mechanic experience. If you don’t have the experience, you should call a professional mechanic.    

The good news is, bearings are easy to replace and also cheap.

Speed Settings Are Incorrect    

If you have a circulator pump that has speed settings, you can check on it. If the speed settings are not compatible, it will make noise.


First, locate the speed settings switch. Now, turn it down one level. If it still makes noise, call a professional mechanic to repair it.

System is Clogged

Rusted water and lubricants can clog the impeller of the pump. After the system is clogged, noise starts to begin.


You have to clean the whole system in the pipe. Make sure you remove all the rust. You can remove the rust by using homemade ingredients. Also, apply a water blowdown. There are professional cleaners to do this job, you may want to call them.   

There you go! Now you can fix any of these problems.


Question: How much cost does it take to replace water circulator pumps?
Answer: Replacing a circulator pump costs almost $400-800. You will also have to pay a professional mechanic at least $200. If you replace it yourself, it can save you money.

Question: How long does a circulator pump last?
Answer: If you use your circulator pump correctly, it will last at least 10 years. If you do not use it correctly it will not last for a year. 

Question: Should my circulator pump be hot?
Answer: It is normal if a circulator pump gets warmer or even hot. Too much heating will cause serious damage. You need to be careful about it.


That’s everything we had regarding circulator pump rattling noise. We hope the issues are clear to you now. 

If the problem still remains after troubleshooting, Contact a professional to fix it.  

Good luck with fixing the noise!