Prepare for the Seasons with an Industrial Boiler Tune-Up

Prepare for winter with an industrial boiler tune-up

Industrial boilers experience differing levels of stress throughout the year. A quality maintenance plan plans around the system’s cycle to ensure problem-free, efficient operation all year round. With the heaviest workloads expected in the winter months, the summer and fall are the perfect time to have your boiler serviced. 

Preventative Maintenance

Regular maintenance promotes boiler health, increasing performance and avoiding breakdowns. So what does regular maintenance mean? In general, (and many state/local boiler codes require that) an industrial (high-pressure steam) boiler should have an Internal Inspection once a year. 

An internal inspection, where the water and fire sides are opened and cleaned, will include testing of safety devices and combustion tuning. However, this can vary depending on operating season, water quality, usage amount, and other operating conditions. Note the Internal Inspection can also known as an Annual Inspection. 

If your boiler is performing poorly or your energy costs are rising, inspect the boiler more frequently. Work with a qualified boiler service company to identify and resolve the issue affecting your boiler’s performance. 

In addition to the internal inspection, external inspections/tuneups are also a great way to keep your boiler running safely, efficiently and with maximum reliability.  External inspections:

  • review the boiler’s external condition
  • test and document the operation of all safety controls
  • tune the burner combustion for the current or upcoming season.

The timing of these external inspections can vary from once to three times per year (or more).  Another option that may benefit some facilities, is a Seasonal Shutdown and Startup, these usually make sense for facilities that only use their boilers for a few to six months per year.

Insustrial boiler inspections internal vs. external

Internal Inspections and Cleaning

Boilers have two sides: fireside and waterside. For cleaning, a technician will focus on these important portions of your boiler. On the fireside, the combustion of gas or oil can cause soot to adhere to the tubes. On the waterside, deposits of limescale and other minerals form along the tubes (or inside the tubes on a water tube boiler). This “scale” builds over time, becomes harder to clean, and can even cause metal corrosion beneath the substance. 

The tubes must be examined for buildup and cleansed of this buildup.  If it is ignored, this corrosion can cause tube or boiler failure. Even before the scale causes issues with tube failure, it is almost immediately having a negative effect on your boiler’s efficiency.  Even a small amount of scale can cause a drastic boiler efficiency loss and an increase in energy costs. 

For example, if a company spends 3.6 million dollars a year on fuel, just .03125 inches of scale buildup causes a 2% increase—72,000 dollars worth—in fuel cost. The good news is that correct maintenance can prevent this additional cost. 

On the fireside, the boiler can experience soot deposits.  These can be caused by improper tuning, leading to incomplete combustion, dirty fuels, or the temporary use of fuel oil as a backup fuel.  Similar to waterside fouling, this soot acts as an insulator between the energy produced by the burner and the boiler’s water, letting less energy transfer to the water and instead escape through the boiler’s stack – lowering efficiency.

Removing Boiler Tube Scale and Soot

Methods to remove the soot buildup and the scale buildup depend on the type and thickness of the accumulation. Soot can usually be removed with a mechanical solution, utilizing a brush or scraper in combination with a soot vacuum. 

Waterside scale can be removed by mechanical means, such as pressure washing or  may need to be  removed with chemicals. This chemical removal uses an acid to dissolve the scale minerals from the tubing. The specific kind of mechanical or chemical tool used, though, depends on the buildup’s composition.  

What is a Boiler Tune-Up? 

There is more that goes into boiler maintenance than buildup removal. A boiler tune-up also ensures your boiler is running efficiently, therefore reducing energy costs. A well-tuned boiler improves safety and extends the boiler’s lifespan, too. 

During a tune-up, your technician will measure the composition and temperature of the boiler products of combustion, known as a flue gas analysis, using a flue gas analyzer.  The information from this analyzer is correlated to an efficiency percentage.  

Looking at the EPA’s boiler tune-up guide, for reference, the air-to-fuel ratio measures how successful the boiler is at converting heat in the fuel into usable energy. The metric measures the amount of excess air that the combustion process produces throughout the operation. 

When the amount of excess air is optimal, the combustion gasses will show minimal unburned fuel as well as excess air. The (safe) minimum amount of excess air for a certain boiler depends on the combustion control type. 

The technician will use the readings from the analyzer to adjust your boiler’s air-to-fuel ratio, a key to maximize your boiler’s efficiency while maintaining a safe air/fuel ratio. Generally, when excess air is reduced by 1.5%, the boiler’s efficiency will increase by 1%. 

The technician will make adjustments over several positions of the burner’s combustion “curve”.  The curve is the range of combinations of fuel valve and air damper position (more specifically, fuel and airflow) from low to high fire. 

Depending on the combustion control strategy in use, the number of points reviewed and adjusted will vary.  For example, a jackshaft type of control may only be adjusted at Low, Medium, and High Fire (due to the limitations of tuning the points in between these positions on this type of control).  On more modern parallel positioning systems, there can be tens of points tuned in making the combustion curve. 

When Should I Schedule My Preventive Maintenance Visits 

The timing of your boiler’s internal inspection is set by state code, usually one year after the previous inspection. However, you can work with your inspector to schedule this inspection at a more convenient time for your facility.

Many of our customers schedule their internal inspections in July during their annual shutdown for repairs and maintenance. If your facility’s steam needs are lower or non-existent in summer, scheduling your internal inspection when the steam load is low is a smart choice.

Preventive Maintenance (PM) visits can be scheduled flexibly to meet your facility’s needs. The number of External Inspections—whether one, two, or three—depends on factors such as boiler size, operating hours, and load.

One benefit of PM visits, besides testing the boiler’s safety devices, is the increased efficiency from tuning the boiler for the current season. Larger, heavily loaded boilers can benefit from three tune-ups per year in addition to the Internal Inspection. Smaller, less loaded boilers may only need one additional PM visit annually. A qualified boiler service company can help determine the optimal number of visits for the best return on investment.

The timing of Seasonal Shutdowns and Startups varies based on your boiler’s schedule. Generally, the Shutdown occurs at the end of the boiler’s use for the year, and the Startup happens just before the boiler is needed again. For example, heating boilers typically shut down around May and start up again around September.

Think of this as a long Annual Inspection or Preventive Maintenance visit, with the boiler placed into layup after shutdown. This applies not only to heating boilers but also to any boiler used in a production process with an extended slow season. Shutting down one or more boilers during these periods can be beneficial. Your boiler service company can provide specific recommendations for seasonal shutdowns and their potential use in your facility.

Fall Boiler Service

As fall approaches, it is the last chance to conduct maintenance to prepare for the cold months. Once you have done yearly maintenance and cleaning, it is soon time to end your boiler’s layup period and get back to work.

Before Restarting Your Boiler After a Layup

In general, before restarting your boiler after summer layup, a technician will: 

  1. Check the combustion air openings for debris/obstructions
  2. Check/set the water level and make sure stack dampers are open
  3. Check the furnace for external substances
  4. Check the furnace and flue passes for any debris accumulation
  5. Verify the manual fuel, steam, and water valves are open

After this procedure, the technician will follow the normal startup sequence—but will continue to monitor the boiler to confirm it and all of the safety systems are operating normally. 


Regular boiler maintenance is essential to minimize downtime and keep your boiler running reliably. A well-tuned boiler will save your business money. Schedule a tune-up with your boiler maintenance partner, WC Rouse, so you’re ready for this winter.

Jeff Lawley

After graduating from Florida State University with a B.S. in Mechanical Engineering, Jeff Lawley headed up the engineering department at Schaefer Interstate Railing. A few years later, he took an Engineering Sales position here at W.C. Rouse & Son, and over the next 8 years, he worked his way up to the position of President of the company.