By Chris Buchanan • October 17, 2018

A Complete Guide to Steam Boiler Maintenance

A boiler is defined as a pressure vessel that produces steam or heats water to heat water and/or provide heat in a building. There are many advantages to using a boiler  such as:
  • Long life span
  • Requires little to no pumping energy
  • Are efficient up to 95 percent or more
  • Are extremely effective in heating a building
Living in an apartment complex or condominium complex often means that the maintenance department takes care of the boiler. However, not everyone has that advantage of someone on-site to maintain their equipment.
The boiler's maintenance in your own home may be difficult to understand because let's be honest, not everyone keeps the owner's manual which may be difficult to follow anyway.
For those of you who do your own steam boiler maintenance, here is a complete guide on what to do, what to know, and how to do it yourself in your own home.
While this guide does not replace having a professional do repairs, it helps you maintain your boiler easier and with more knowledge.

Proper Care of Your Steam Boiler

Referenced above was the owner's manual. Yes, they can be confusing and often times lost. However, it is important to try to keep up with it and refer to it when needed.

One of the keys to successfully maintaining your boiler is to read the owner's manual for the equipment. In this process, make sure to pay attention to any specific instructions from the manufacturer about your unique boiler. If possible, keep a copy of the startup/inspection manual for your boiler on file, so you can always refer to it at a later date.

If you notice any problems or have any concerns, you should immediately report the problem to the service technician. In any case, the annual service should always and only be performed by an experienced service agency or qualified installed licensed to perform maintenance.

Control and Safety Devices

Many in-home accidents from boilers are due to a few factors such as operator error, low water cutoffs that have malfunctioned, and poor maintenance. This is why proper maintenance is a must when it comes to ensuring a safe steam boiler.
Here are a few common control and safety devices to check.

Low Water Fuel Cutoffs and Water Level Control

Often found in one single unit, each of these devices perform separate functions. It is best that your boiler have them as separate devices in the form of a primary and secondary low water fuel cutoff.

Safety Valves

Always keep up with maintenance on your boiler. The safety valves are there as the last step of defense. What they do is relieve the pressure generated in case there is a problem with the unit. Make sure to test them on a regular basis since they can easily malfunction the same as other safety devices.

Fuel System

The fuel system is one of the most crucial parts of the steamer boiler. With a fuel system that is not working properly, there are many areas it affects. For instance, the loss of heat transfer, higher fuel costs, or even an explosion can take place. If you are unsure of how to maintain the fuel system, it is a good idea to consult with a professional but it should always be maintained to keep everything working and safe.
Make sure you also analyze the air to fuel ratio. As stated by the STI Group:
The air-to-fuel ratio of oxygen to fuel being burnt during combustion is important for optimizing the boiler’s efficiency. If too much air is used, too much heat may be expended; by contrast, if too little air is used, an incomplete fuel burning may occur, resulting in waste. Analyze this delicate ratio and make adjustments as necessary to optimize efficiency.

The Water Gauge Glass

Keeping the water gauge glass cleaned and maintained is extremely important. Sometimes known as the sight glass, this allows the user to see the water level in the boiler. If the water gauge glass is broken, leaking, stained, or clogged it may give false readings. If any of this happens, make sure to replace the glass. While this requires shutting the boiler off, it is important to negate any damage done by false readings.

Stack Temperature Gauge

This device reads the temperature of the flue gas leaving the boiler. Excess soot or scaling in the tubes may be indicated by a high stack temperature reading and it is also possible that gases are bypassing the heat transfer surfaces due to a baffling in the boiler that has burned through or deteriorated.

Other Areas of Steam Boiler Maintenance

There are other areas to take care of and maintain that keep your system working efficiently and will extend its life.

Maintain Boiler Logs

In order to always be in-the-know about everything to do with your boiler, a logbook of your boiler's operations is imperative. It lets you know when there have been significant changes, what areas were maintained and when they were maintained, as well as ensuring that the steam boiler is getting the proper attention it requires.
There are quite a few things to include in your boiler logs but two important notations are if the boiler is cycling often and the firing rate to meet the given hot water or steam load.
If the boiler’s firing rate continuously cycles over short periods of time and with fairly small variations in load – this should be noted.
If you find excessive cycling or a firing rate that is sporadic or continuous, these may be issues that call for a professional.


If you live in an area with hard water, you will often find excessive lime in the boiler. This lime-scale prevents the boiler from working efficiently and affects its heating capacity. If you do find that you have lime, de-scaling the boiler is necessary.

Dust Removal

Due to how a boiler operates, dust is something to be aware of and it will accumulate in the room and on the boiler. Be sure to periodically clear away any dust you find, especially on the boiler itself. For instance, a boiler fan that is dusty will not work as well and this affects heat output.


This form of maintenance is essential for most moving parts and the boiler is no exception. Be sure to keep your boiler lubricated and pay special attention to areas like the pumps and fan.


A couple of times a year, make sure to clear all of the water from the boiler. If you do this after the winter is over, this is the best time because the boiler has worked at full capacity. This helps remove things that accumulate in the boiler like dust, grit, dirt, and lime-scale. Once you flush it out, be sure to clean the interior and before you refill the boiler, add new gaskets if needed.

A Daily Checklist

While the majority of maintenance is not a daily affair, keeping up with the little changes means always knowing how your boiler is performing. There is plenty to maintain a different times such as a monthly checklist, but a daily checklist is just as important.
Here are a few things to do every day to ensure your boiler is functioning at its best.
  • Listen for unusual noises or vibrations that are not the norm
  • Look for water leaks under and around the boiler
  • Look for blockages in the combustion air opening
  • Remove anything blocking the boiler such as boxes, equipment, and items that interfere with its function
  • Check for ice, snow, or other debris that may block the vent termination
  • Look at all gauge readings such as temperature and pressure to ensure they are at the proper levels
  • Watch for error codes and if found, report them to a professional or refer to your owner's manual if possible
  • Complete a visual inspection of the entire boiler
  • Check for unstable water levels
  • Maintain a proper temperature in the boiler room which should not be lower or higher than stated in the owner's manual
  • Look at the steam pressure and see if it varies during different loads
  • Visually inspect the burner

Weekly Checklist

  • Check all relief valves
  • Check water level controls
  • Check boiler operating characteristics
  • Inspect for water/steam leaks
  • Inspect boiler for air leaks
  • Check water treatment procedures and blowdown
  • Inspect all linkages on fuel valves and combustion air dampers
  • Check flue gas temperatures and composition
  • Check pilot and burner assemblies

Monthly Checklist

Along with a daily and weekly checklist, there is also a few things to do each month. There are not as many as with the quick weekly check, but are equally important.
  • Look for leaks or weeping on the boiler relief valve and the relief valve discharge pipe
  • Look for blockage, deterioration, or leaks on the flue gas vent piping and combustion air piping.
  • If your system is a condensing boiler, check out the drain system, drain line, drain trap, and PVC fittings for blockages

Periodic Checklist

Last but not least, here are a few things to check every so often - every quarter is a good length of time or even every other month. These can be done while you are doing the monthly checklist or even the daily checklist.
  • The low water cutoff is important so that the water levels are not too low as recommended by the manufacturer so make sure to schedule to have it tested
  • Look at the burner flame if you can and if it does not look right or different from the usual look, make sure to correct whatever is causing it.
  • Check for leaks in the boiler hydronic piping

A few notes about the burner flame

A proper pilot flame should be blue in color with an inner cone engulfing thermocouple that glows a cherry red color.
If you see something different, here are a few issues that cause this:
  • If you see a flame blowing past the thermocouple or a large flame lifting past it, this may mean it is over-fired.
  • If you see a small flame where the inner cone is not engulfing the thermocouple, this may mean it is under-fired.
  • A yellow flame tip may mean a lack of primary air.
For the main burner flame, dust can cause yellow or orange streaks, large flames mean it is over-fired, a small flame is under-fired, and the same thing happens with a lack of primary air - a yellow flame tip.

Startup Checklist

Whether you do this during the startup time or once a year, here are some things that need to be checked by someone who is a professional. The actions a technician should take are:
  • Test operating controls, test safety controls, and check control settings
  • Inspect the heating system and repair any issues
  • Make sure the air inlet and vent terminations are free from obstructions
  • The boiler's heat exchanger should be inspected and cleaned
  • Look at the venting system for things like blockage, corrosion, and deterioration
  • Make sure the joint and pipe connections are secure
  • Check the wiring and boiler connects to be sure they are intact
  • Examine and clean the burner assembly, igniter, and sensors
  • Check the water pH levels to ensure proper range
  • Look at the condensation system, clean, and flush if it is necessary for the system
Maintaining your own steam boiler may seem difficult or even intimidating, but following this checklist makes it easier to section off into daily, weekly, and periodic groups of maintenance items that are simple to implement.
Don't allow the overall list to seem like too much. Most of the checklist items take just a few moments of your time and if you do these as often as you should, they will become second nature so that you automatically see if something needs further attention or the help of a professional.