Every boiler operator wants a smooth-running, efficient, hassle-free boiler. But the truth is, we don’t live in a perfect world. Things happen, and sometimes those things are boiler parts failures. Beyond normal wear and tear, these are the parts that tend to fail the most often.
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Flame Scanners
If you’ve ever attended a sporting event, you know that sometimes the ball (or puck) can fly into the crowd. It’s usually those with a front-row seat that end up getting hit (or getting a souvenir.) It’s no surprise, then, that flame scanners tend to fail more often than other boiler parts. After all, they have a front-row seat to some of the harshest conditions in any industrial plant: your boiler’s fire side. Every day, flame scanners are right there by your boiler’s burners, exposed to high temperatures hour after hour.
In addition to the heat, flame scanners are also exposed to a lot of regular vibration, as well. Some of that vibration comes from pressure oscillations that occur during the combustion process. If the fuel/air mixture isn’t set properly, those pressure fluctuations can get even worse, developing into low-frequency rumbles that subject the flame scanner to even greater stresses.
Your flame scanner is also subjected to vibrations from the forced-draft and induced-draft fans in your boiler. As they operate, they naturally create vibrations, especially if they are out of balance or have worn bearings. These vibrations get transferred to the flame scanner, further shortening its life.
Why Flame Scanners Fail:
- Harsh environment
- Vibration from improper fuel/air mixture at the burner
- Vibration from nearby fans
Indicators a Flame Scanner is Going bad
When a flame scanner starts to go bad, it won’t be doing its job consistently. The electronic signal it sends to the boiler’s control system may be intermittently interrupted, which might trip error codes or give false flame detections.
If your flame scanner is sending inconsistent signals, causing nuisance shutdowns, or failing to detect flame properly, it may be time for inspection or replacement. Flame scanners operate in one of the harshest environments in your boiler, and even normal wear can impact performance over time. WARE’s BoilerWAREhouse.com stocks a wide range of flame scanners and replacement components, so you can quickly restore reliable combustion monitoring and keep your system running safely.
LOW WATER CUTOFF HEADS AND PROBES
While flame scanners do their best to monitor your boiler’s fire side, there’s another component that handles the job of making sure your water side is properly supplied. It also happens to be another point of frequent failure in your boiler system. We’re talking about the systems that protect your boiler from a low-water condition.
Low water cutoff heads and probes perform the crucial task of monitoring the water level in your boiler, and sending an alert or shutting the system down if the water drops below an acceptable level. They’re absolutely essential for safe, efficient operation, because if the water level drops too low, your boiler can suffer multiple types of life-shortening damage.
Without enough water to absorb heat, the metal of your boiler’s pressure vessel will start to overheat. That can cause warping, cracking, and metal fatigue that will eventually lead to pressure vessel failure. In fact, if the water level drops too low, the flame and heat in the boiler can actually melt the metal of the pressure vessel.
Flame temperatures inside the boiler are higher than the melting point of the steel. The only thing that keeps your pressure vessel from melting is the water inside that absorbs that heat. If the steel melts and the water leaks into the fireside of the boiler, that is when the worst type of boiler failure can occur. Steam under pressure will expand at a rate of 1600 times when it exits to the atmosphere. If it escapes due to melted metal, this will result in a catastrophic failure that can take out buildings and injure multiple people even if they are not in the boiler room when it happens.
Now that you know how important low-water heads and probes are, it’s time to talk about why they fail. The first reason low-water heads can fail has to do with the impurities in the water we just talked about. If the boiler doesn’t have regular blowdowns to purge sediment, it can hang around and collect on the floats used in mechanical low-water monitoring equipment. If the floats can’t move freely, they can’t raise and lower with the level of the water. That means you can end up with a situation where the water level drops low enough that the impeded float is just suspended above it. If that float can’t go low enough to trigger a low-water alert or a boiler shutdown, the boiler will just keep on firing even though it doesn’t have enough water in it.
Speaking of blowdowns, even if you do them regularly, you can still damage your low-water floats if you aren’t careful. Blowing down too fast can actually create a momentary vacuum, one that can collapse the float and render it unable to do its job. Improper blowdowns can also damage the switches in a low-water cutoff system, making them work improperly or not at all.
Another way that low-water cutoff equipment can be damaged has to do with water treatment. If the water in your pressure vessel isn’t treated properly, it can begin to attack the metal components and the float in your low-water cutoff system. Improper water treatment can also be harmful in boiler monitoring systems that use probes instead of float switches.
Probes work by measuring the electrical conductivity of the water. If the water level falls below the minimum, the change in conductivity will create an alert in the boiler’s monitoring system and sound an alarm or shut the boiler down entirely. If the water in the pressure vessel isn’t treated properly, it can foul the probes and affect their ability to detect accurate conductivity. This can result in false positives or false negatives coming from the probes, which can cause either unnecessary shutdown or pressure vessel damage.
WHY LOW-WATER HEADS AND PROBES FAIL:
- Too much sediment
- Improperly treated water
- Improperly performed blowdowns
How You'll Know a Low Water Head and Probe is Failing
When a low-water cutoff head or probe is starting to fail, it may let the water level fall too low before sounding an alarm or shutting down the boiler. That’s why visual water checks are so important as an ongoing backup. If your boiler monitoring system starts to generate low-water alarms or shutdowns even when the water level is fine, that’s another sign that your probes or heads need maintenance or replacement. These items should always be inspected by trained staff or professionals regularly when doing open and closes to prevent operators from having to rely solely on the alarms. Having a good water treatment and inspection program isn’t just to protect the equipment from failure, it also serves to stop catastrophic situations from occurring.
If your low-water cutoff system is showing signs of fouling, delayed response, or false alarms, it’s critical to address the issue immediately. These components are essential to boiler safety, and failure can lead to serious damage or hazardous conditions. Whether you need replacement probes, cutoff heads, or related components, BoilerWAREhouse.com offers the parts you need to maintain accurate water level protection and keep your boiler operating safely.
BOILER FEED PUMPS
As we all know, boilers use a combination of temperature and pressure to generate steam. Because of this pressure, you can’t just open your boiler and pour feedwater in when it’s needed. Instead, that feedwater has to be forced into the boiler’s pressure vessel by pumps. And those pumps are another common point of failure in many boiler systems.
One of the main reasons that feedwater pumps fail has to do with temperature. In many boiler systems, the deaerator not only removes oxygen from feedwater, it also acts as a reservoir to store excess feedwater. If the temperature of the water in the deaerator is allowed to go higher than the temperature for which the feedwater pumps are rated, it can damage the seals of the pumps and cause them to leak or wear prematurely.
While water that’s too hot can damage your pumps, water that’s too cold can also do a number on them, as well. If you flood a boiler with water that’s too cold, it can collapse the steam in the pressure vessel, which lowers the pressure inside. That sudden loss of pressure can cause the suction head to drop so low that the water entering the pump from the deaerator partially flashes to steam. That causes cavitation, or voids in the pump. Those voids can cause the pump to spin too fast, or to spin out of balance.
Large draws on the boiler can also cause the same situation to develop. If sudden demand creates a loss of steam, the pressure will drop, and you’ll get more cavitation in your feedwater pumps, as well.
WHY FEEDWATER PUMPS FAIL
- Deaerator temperature is too high, damaging pump seals
- Deaerator temperature or sudden demand create a drop in pressure that creates cavitation
How You'll Know a Boiler Feed Pump is Going Bad
If your feedwater pumps are leaking or underperforming, they may need to be maintained or replaced. That’s also a good time to check your deaerator temperature against the temperature rating of the pumps to make sure you aren’t running water that’s too hot through the pumps.
The sound of a damaged or cavitating pump can sound like marbles clanging and grinding inside the pump. If you hear that sound, immediately check your deaerator temperature or the amount of steam that is being demanded of your system. The truth is, though, if you hear the marble sound, it’s likely already too late to save the pump and it will have to be rebuilt or replaced.
If your feedwater pump is leaking, underperforming, or showing signs of cavitation, it may require repair or replacement to prevent further system damage. Pump failures can escalate quickly and impact your boiler’s ability to maintain proper water levels and pressure. BoilerWAREhouse.com carries a range of feedwater pump components, rebuild kits, and replacement parts to help you get your system back online quickly and efficiently.
If you’re experiencing any of these common boiler failures, having the right replacement parts on hand can make all the difference in minimizing downtime. From flame scanners and low-water cutoff components to feedwater pump parts and more, BoilerWAREhouse.com offers one of the largest selections of boiler parts in the nation, with fast shipping to keep your operation running. And if you’re not sure exactly what you need, WARE’s team is always here to help.
Most Common Boiler Part Failure FAQs
What are the most common boiler failures?
The most common boiler failures include flame scanner malfunctions, low-water cutoff failures, and feedwater pump issues, often caused by heat, vibration, poor water quality, or improper maintenance.
Why do flame scanners fail in boilers?
Flame scanners fail due to constant exposure to high temperatures, combustion vibrations, and airflow from nearby fans, which can damage internal components over time.
How can you tell if a flame scanner is failing?
A failing flame scanner may send inconsistent signals, causing false flame detections, nuisance shutdowns, or error codes in the boiler control system.
What causes low-water cutoff failures?
Low-water cutoff systems often fail due to sediment buildup, poor water treatment, or improper blowdowns, which can prevent accurate water level detection.
Why is low-water protection so important in boilers?
Low-water protection prevents overheating and potential pressure vessel failure. Without enough water, boiler metal can overheat, warp, or even melt under extreme conditions.
Why do boiler feedwater pumps fail?
Feedwater pumps commonly fail due to excessive temperature, cavitation, pressure fluctuations, or seal damage caused by improper operating conditions.
What are signs of a failing feedwater pump?
Common signs include leaks, reduced performance, and a grinding or “marbles” sound caused by cavitation inside the pump.
How can boiler failures be prevented?
Regular maintenance, proper water treatment, routine inspections, and monitoring system performance can help prevent most common boiler failures.
Can WARE help diagnose and repair boiler failures?
Yes. WARE provides expert boiler service, troubleshooting, replacement parts through BoilerWAREhouse.com, and training through Boiler University.