In-Line Heating Pump Troubleshooting

Heating pump maintenance isn’t something that needs to be completed often. So when it comes time to perform maintenance on your pumps, it can feel more unfamiliar than working on a flushometer or other facility fixtures that require more frequent repairs. Reading this heating pump troubleshooting article will help you identify the problems with your pump, and know what needs to be done to repair it. 

This article shares the top 4 items that break in a popular 3-piece, in-line heating pump (note that although it is considered a 3-piece pump, it actually has 5 major parts). It includes what signs to look for, along with what your next steps should be. Also included in the article are pump oiling instructions, and additional tips to help you increase the longevity of your pump, and deter you from making common pump maintenance mistakes. 

The pump featured in this article is the Bell & Gossett 100 Series Single Phase Circulating Pump (B & G model number 106189). We chose to highlight this pump because it’s a popular pump found in a variety of settings. Note: These maintenance tips can be applied to other similar heating pumps too, but just keep in mind that these tips might not match up exactly if you are working on a different pump.


B&G Series 100 Pump Part Identification

The 5 major parts of the Bell & Gossett Series 100 Circulating Pump are the motor, coupler, bearing assembly, impeller, and the pump body. The motor sits in the ring motor mount set. The bearing assembly includes all of the following parts: bearing bracket, shaft & sleeve, impeller key, front bearing gasket, front bearing, seal kit, body gasket, and impeller nut. The pump body is also called the volute. The above image points out the seal kit, located in the seal assembly, because (spoiler alert) it’s usually the first part in the pump that needs to be replaced (more on that below). Also noted in the image are the points in the pump that need to be oiled (details on oiling can be found towards the bottom of the article). 


Bell and Gossett Circulating Pump Troubleshooting

Here are are problems, causes, and solutions for in-line pumps. They are listed in order from most common to least common. 

  1. PROBLEM: The pump is leaking where the bearing assembly meets the pump body. 
    CAUSE: The seal kit is breaking/broken or the bearing assembly is breaking/broken.
    SOLUTION: For most in-line pumps, including series 100 Bell and Gossett pumps, the seal kit is located in the bearing assembly. When that is the case and this problem is occurring, it is recommended you replace the entire bearing assembly. This goes for whether the seal kit is broken, or if the bearing assembly is broken. This is because there is less room for error when replacing the bearing assembly than there is when you install the seal kit only. It’s also worth noting that the bearing assembly is under warranty for at least a year, whereas the seal kit isn’t, since manufacturers have to account for potential user error during installation. It is also a much easier installation to make. Find the bearing assembly in our Bell & Gossett Pumps page.
  2. PROBLEM: The pump shaft is not turning, but the motor shaft is.
    CAUSE: The coupler is broken, or is going to break soon. There are two types of couplers your pump can use: a spring coupler, or a 3-piece coupler (also known as a Woods coupler, which is the manufacturer of this coupler style). For 3-piece couplers, you’ll know they are breaking when you see little shavings on the floor underneath the location of the coupler. For spring style couplers, which are used for booster pumps like this one, you will hear thuds or bumps, which will signify that the coupler needs to be replaced. The coupler is designed to fail before other pieces. It most often occurs when a pump is misaligned. Over-oiling the motor can also cause the coupler to break. Read our oiling tips below to ensure you do not over-oil your heating pump. 
    SOLUTION: Replace the coupler. Keep in mind when replacing a spring style coupler, it needs a little bit of space to account for expansion during heating. When hooking the coupler pieces together, leave a quarter inch of space for the coupler to grow. Find the coupler replacement you need in our online selection of Bell & Gossett couplers. If you don’t see the coupler you need, call to place your order.
    *Watch our Troubleshooting your Bell and Gossett Series 100 Pump Video for more information about coupler replacement and ring mounts. 
  3. PROBLEM: The motor is not running. 
    CAUSE: The motor was not being oiled/maintained, something dripped on the motor, or the wrong oil was used for the motor. If you over-oil, the oil gets into the motor mount, making it soft, which can then cause the unit to sag and cause the coupler to go as well. Over oiling can also cause oil to get on the motor windings, which causes them to act as a dust magnet, thus causing the motor to overheat and eventually fail.
    SOLUTION: Replace the motor. Find the replacement motor in our Bell & Gossett Pumps page.

To find additional Bell & Gossett pump parts, including an impeller, motor mount set, pump seal kit, and pump body gaskets, view the Miscellaneous Bell & Gossett pump parts page. 


Bell and Gossett Series 100 Oiling Instructions

Bell and Gossett Series 100 Oiling Instructions

When installing a new pump, it is important that you oil it. Your pump will come with a tube of oil labeled with numbers that describe how much oil to add to the 3 oiled locations. 1 goes into the oil well. 2 and 3 ( the lesser amounts) go to the other two oil ports. Besides the initial installment, oiling the pumps is done on-demand, and very minimally. Your pumps should be inspected at a minimum of every 6 months. If you notice the pump squeaking, then more oil needs to be added. When a motor is making squeaking sounds, then, and only then, should you add a couple of drops (2-3) of oil into the motor well.


Equiparts is a distributor of all major heating pump manufacturers, including Bell & Gossett, Armstrong, Taco and Hoffman. We carry all of their pumps and the repair parts needed to maintain them. Call for additional help, or to place your order.

Toll-Free: 800-442-6622
Pittsburgh: 412-781-9100

Phone hours: Monday-Friday 8:00 AM – 4:00 PM EST

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