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Boiler Feed Pump Troubleshooting

If you own or manage an apartment building in New York City, your boiler is a lifeline for heat and hot water. Therefore, keeping your boiler running smoothly should be a top priority. Here is the Antler Pumps guide to basic boiler feed pump troubleshooting. We have included some solutions you can try on your own, and we have also indicated when it’s better to call in the pros. Some pump issues need expert service, especially if the interior of the pump needs to be exposed and repaired.

Function of the Boiler Feed Pump

Keeping the tank filled

The purpose of a boiler feed pump is to keep your boiler tank at the proper level. The feed pump helps determine when the tank needs filling and sends either fresh water or recycled steam condensate there.

Boiler feed pumps typically operate at very high pressures and are made to withstand high temperatures as well. As multistage pumps, they use multiple impellers inside to move water from the intake side to the exit, where it enters the boiler.

Two Types of Boiler Feed Pumps

Horizontal or vertical?

It’s good to know which orientation you have for your boiler feed pump, particularly if you’re trying to schedule service or describe a problem over the phone to a pump specialist. The pump type is determined by the orientation of the pump to the shaft.

Horizontal pumps are installed frequently in industrial settings. This is a larger pump that can handle high-pressure and high-volume pumping needs. Vertical boiler feed pumps are perfect when space is an issue, as they are smaller. You’ll find this all-purpose pump used when less than 900 ft of pressure is required. They are a bit more complicated to work on because they often need to be removed for repairs and upkeep.

Common Boiler Feed Pump Problems and Solutions

Pump doesn’t run or only runs sometimes

If your boiler feed pump won’t turn on or only turns on intermittently, it could be due to one of several problems. Most often it’s a problem with the sensor that triggers the pump to run automatically. The sensor in the main tank can become stuck and needs to be loosened. Sometimes the sensor mechanism breaks, and that part needs to be replaced.

Other causes include:

• Electrical malfunction (see below)
• Problem with water source (blockage) or steam return lines for condensate that requires detective work further upstream from the boiler feed pump
• Pump internal components clogged or broken (best fixed by professionals)
• Pump not level

Flooded boiler

Sometimes a faulty valve at the pump’s entry (AKA inlet) side can allow more water than needed to pass into the feed pump. This is especially likely if you’re using fresh water and the municipal water supply pressure is very high.

You can try cleaning or replacing the valve in question (or we can do that for you). Long-term, you probably want to make sure your water is filtered to remove sediment or mineral scale. If high pressure is an issue, a pressure regulator placed where the water enters your property is recommended.

Flow rate too low

Sometimes we see a boiler feed pump that’s limping along – it’s pumping water, but the rate is lower than desired. There are several possible causes for this:

• The pump is the wrong size for the boiler or demand (more likely if you changed the boiler or have added units to the building) and should be upgraded.
• The pump has a clog somewhere, such as foreign matter in an impeller.
• There is a loose seal, O-ring, or gasket that is allowing water to leak out (must be replaced).
• A leak is caused by corrosion that forms holes in or near the pump (boiler water should be treated to achieve the proper pH).
• The pump settings are not correct (usually needs to be sped up).
• Mineral scale or sediment (see below) has blocked a strainer or other part of the system (sometimes cleaning the strainer is a simple solution).

Abnormal or loud noise emanating from the pump

If you’re lucky, an unusual noise coming from your boiler feed pump is simply due to a loose mounting. Check to make sure all the straps and hardware are firmly attached, as these can occasionally work loose.

If the mounting looks solid, the next most likely cause is friction, which can result from multiple factors:

• Old or misshapen bearings that need replacement
• Need for oil or other lubricant (or water mixed in with oil)
• Worn impeller or impeller out of alignment and scraping on another part or the pump casing
• Overheating of the pump itself or the surrounding environment

Usually a boiler room that becomes too hot to touch will cause the pump to shut off, along with other parts of the system. If you use pump controllers, you’ll get alerts sooner that something is amiss, so you can make changes before the system shuts down.

Sediment or mineral scale buildup

As mentioned above, sometimes sediment or mineral deposits can accumulate on your pumps. If this is the case, you’ll probably notice this issue on other parts of the boiler system and your plumbing components. In general, New York City’s water isn’t too hard, although there are some areas of Queens where different water sources make for harder water.

Sediment can be a problem with old pipes, as bits of rust and other detritus find their way into the boiler. A water filtration system for the building can solve this and protect your plumbing too. We work in concert with our partners at Sanitary Plumbing when filters are needed.

Electrical problems

Malfunctions of the pump’s electrical supply can cause operational issues. This can be a loose plug, frayed wire, or problem with the associated circuit breaker on the electrical panel. If there is any equipment on the same circuit that’s failing simultaneously, it’s a pretty good sign you have an electrical cause. If you suspect electrical problems but can’t put your finger on the issue precisely, it’s wise to have a licensed electrician go over the system with you.

These are the most common troubles we see with boiler feed pumps. Some other problems we encounter include:

• Boiler priming or surging due to dirt, which in turn causes the feed pump to activate when it shouldn’t
• Plugged vent line in the condensate receiver
• Condensate pump discharging into a Hartford loop, forcing the pump to turn on
• Steam return line traps incorrectly installed
• Check valve not closing properly, causing boiler tank water to run back where it came from
• Worn pump shaft or bushings

When necessary, we work with Calray Boilers, also part of the Omnia Mechanical Group, to resolve these issues that relate to the entire boiler system and not just the pump.

Are you experiencing problems with your building’s boiler feed pump that you can’t fix on your own? Don’t let the problem get worse by waiting. Call Antler Pumps at 212-534-2500 or schedule an appointment for a service call using our easy online form.