Common Boiler Problems and Troubleshooting Guide

Rachel Cherem

Written By Rachel Cherem

Published 04/15/24
Common Boiler Problems and Troubleshooting Guide

It’s easy to lose your cool with a touchy boiler. Some boiler problems and solutions require a professional touch, which rarely comes cheap, but there are a few issues—fortunately—that the layperson can resolve.

The Liberty Home Guard team has compiled some information below to help you sort out your busted boiler. Read on for an overview of common issues that afflict water boilers and the consequences of ignoring them. We’ve also shared some troubleshooting tips to get your boiler back in working order.

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Symptoms of a Faulty or Poorly Maintained Boiler

Boiler broken? Even if you don’t think so, you might be surprised. A boiler in disrepair might not present symptoms that are immediately obvious to the average homeowner. Here are some signs that your boiler is due for a tune-up.

  • Poor Heat Distribution The most obvious indication of boiler trouble is the absence of heating, but be mindful of uneven heating as well. Pockets of warmer or cooler air could result from drafts and poor insulation, pressure differentials, or obstructed registers, but once ruling these possibilities out, you should check that your boiler is working consistently and efficiently.

  • Pressure Problems Check the gauges on your boiler every so often—at least weekly or biweekly, particularly in colder months. Your boiler’s pressure should stay within the recommended range dictated by the manufacturer. High pressure can spell trouble, and low pressure can mean inefficient operation.

  • Off Smells Your boiler shouldn’t emit a particularly distinctive odor. Don’t ignore strange smells from your boiler, even if it seems to be working fine. A burning smell or the odor of gas, even if faint, can suggest a significant safety hazard. Other foul odors, such as sulfur or mildew, can indicate problems that will lead to inefficient operation.

  • Temperature Extremes Monitor your boiler’s thermostat. Ensure that the temperature matches the manufacturer’s specifications. 

  • Corrosion Make sure your boiler is not developing rust. Corrosion suggests a leak or excessive humidity wear the boiler is housed. Left unchecked, rust will eat away at the boiler until it severely hampers its functionality.

  • Leaks A properly kept boiler will not leak. Periodically look for evidence of leaks, such dried streaks on the sides of the boiler, puddles, and stains or discoloration on the ground. Never leave a leak unaddressed.

  • Soot and Grime A boiler might accumulate some dust, particularly in an unfinished area of the home, but other signs of neglect are more worrisome. Black soot and grime suggest inefficient burning, failing seals, or other flaws.

  • Short Cycles Boilers should not be cycling on and off frequently. If you’re hearing your boiler kick on and off many times throughout the day, it’s a sign that the system can’t maintain a target temperature.

  • High Energy Bills One last place to look for boiler trouble: the mail. It’s a good idea to track your energy expenditure over time. If there’s a steady uptick that can’t be ascribed to colder weather or increased energy costs, it may be a sign that your boiler is slowly failing.

Causes of Boiler Explosions

Most boiler problems or malfunctions have predictable effects: poor heating, inefficient energy consumption, shortened lifespan, or appliance breakdown. In extreme cases, however, neglect can lead to a dangerous blowout. Why do boilers explode? Ultimately, explosions stems from two main causes:

High Pressure 

Boilers typically use pressurized steam to transfer heat. If the pressure within the boiler builds up to untenable levels, the entire system can rupture at a weak point. 

Excess pressure within the boiler can arise because of a blocked relief valve, malfunctioning regulator, or overheating. This is why it is critically important to monitor the temperature and pressure gauges on your boiler. One of the signs your water heater is going to explode can be a wildly high pressure reading.

Pressure can also increase when the water level within the boiler drops, which may be due to a leak, plumbing issues, or even malfunctioning pumps or sensors. If the water level drops, the boiler can overheat the limited supply of water within, creating extremely hot and highly pressurized steam that the boiler cannot contain.

Bear in mind that it is also possible for the pressure to be at the recommended level, but if part of the boiler is damaged or corroded, its structural integrity could be compromised enough for an explosion to still result.

Leaking Gas 

Combustion is another potential cause of a boiler explosion. A gas or fuel leak is the primary concern here. If gas is leaking through a corroded or improperly fitted fuel line, it can accumulate within or around the boiler. The boiler itself or a nearby electrical appliance could provide the single spark the gas needs to ignite. 

Gas leaks pose obvious fire hazards, but there are health consequences to consider as well, even if the gas never results in a boiler explosion. If you do smell gas in the vicinity of your boiler, immediately turn off the gas at the source and open the windows or promote ventilation. Then contact a professional to have the situation checked out.

Common Boiler Problems and Troubleshooting Techniques

If you do notice any problems with your boiler, big or small, attend to them as quickly as possible. Some require the attention of a pro, but others you might be able to at least diagnose on your own. Refer to the troubleshooting guide below.

If your boiler isn’t generating heat or hot water…

  • First check the power supply at the boiler to ensure it’s receiving power. Check any indicator lights, examine power cords and outlets for damage, and confirm at your breaker box that the circuit is receiving power.

  • If there are no apparent issues with the power supply, check that the pilot light hasn’t gone out.

  • Confirm that the settings are correct. If your boiler is on a timer, for example, a recent power outage could have reset the clock, resulting in heat not triggering at the preset time.

  • Assuming all settings and controls are accurate, confirm that the thermostat has power and doesn’t need a battery replacement. Try increasing the temperature slightly to see if it triggers the boiler to kick on.

  • Check the pressure gauge to confirm that the pressure within the boiler isn’t too low. If it is, refer to the manufacturer’s documentation to repressurize or recalibrate the boiler.

  • Persistent problems could be the result of electrical problems, faulty valves, or even frozen lines. 

If your boiler is generating hot water but no heat…

  • Fortunately, the presence of hot water means your boiler is still working. Check the radiators and determine if the pipes leading to them are hot to the touch. If the pipes are warm but the radiators aren’t heating up, try bleeding the air from the radiators. A release valve can eliminate the airlock and get the radiators warm again.

  • If you don’t need to bleed your radiators, check the boiler’s settings. The boiler could be set to only provide hot water, which might be likely if you’re coming off the summer and turning on the heat for the first time. It’s also possible that the timed settings aren’t calibrated properly.

If your boiler is leaking…

  • If you notice puddles, drips, or rivulets running down the side of the boiler, try to determine where on the boiler the water is coming from. This can help you diagnose a loose fitting, bad valve, or warped or corroded seal. You might be able to tighten some fittings on your own with a wrench, but unless you’re confident in what you’re doing, reach out to a professional to have the situation remedied.

  • Moisture can also be the result of a failsafe on the boiler, as water can be released from a valve when the temperature or pressure is too great. Check the thermostat and pressure gauge and adjust the settings as necessary.

If your boiler is short-cycling…

  • A boiler that is frequently turning on and off is struggling to maintain temperature. Check that the thermostat is receiving power and functioning properly. Replace the battery or power source if necessary and ensure the thermostat is set to a reasonable temperature as recommended by the manufacturer.

  • Next, confirm the pressure is high enough within the boiler. Read the pressure gauge and repressurize the boiler as needed, again according to the manufacturer’s specifications.

  • Finally, confirm that the water level is high enough and water flow unobstructed. If there are no problems here, reach out to a professional tech.

Other boiler problems—such as the presence of soot, grime, or corrosive forces—likely need the attention of a professional. An expert can determine the source of the problem and tell you whether the boiler can be saved with a settings recalibration or replacement part, or if the entire unit needs to be replaced. 

In rare circumstances, a professional may recommend relocating the boiler, perhaps to an area with greater ventilation or to a more central location where it could service the home more efficiently. The cost to move a boiler can be high, however—anywhere from several hundred to several thousand dollars—and the expense compared to the potential gain may not be worth the trouble.

Preventative Maintenance for Your Boiler

It goes without saying that regular boiler maintenance will extend its lifespan and help you avoid many of the problems described above. It’s wise for homeowners to conduct routine inspections—just a quick once over to check the gauges and confirm there aren’t worrying signs of trouble—but professional servicing is essential as well.

To mitigate the cost of your boiler’s upkeep, consider a home protection plan or warranty with explicit boiler coverage. Learn about the services Liberty Home Guard supports by calling (866)-700-5422.


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