Essential Spare Parts to Keep in Your Boiler Room

essential spare parts to keep in your boiler room

Keeping in-house boiler spare parts is a great way to avoid downtime and costly overnight shipping. Even well-maintained boilers do break down sometimes and often during the worst times. 

This post will list critical pieces of spare equipment that you should consider having on-site. 

Flame Detector

A flame detector is a crucial control and safety boiler part that detects the absence or presence of flame within the boiler. Industrial manufacturers use a variety of flame detection technology. For instance, there are UV scanners, IR scanners, Flame Rods, and more.  Some use a “self-check” feature to verify the operation of the scanner.  The choice of the scanner is dictated based on the fuel being burned, and the furnace construction and position of the scanner.  

So how does a flame scanner work? Regardless of the type of scanner used, the primary function is to “look” to see if a flame is present. The scanner is an integral part of the boiler’s flame safeguard system. If the flame goes out, or if a flame is detected during part of the boiler cycle when it should not be present, the boiler will shut down to avoid an explosive environment when raw fuel builds up.

Flame scanners are necessary when running fired equipment. You will need a replacement ready in case of part default. 

Safety Relief Valves

A boiler safety valve limits the amount of steam pressure within a boiler to prevent over-pressurization that could damage the equipment or even cause harm to people inside the boiler room. Excess pressure pushes the valve seat, forcing it to open against spring tension. The relief valve closes when steam flows out of the boiler, and the pressure falls. 

Code and standards require safety relief valves to be inspected annually. You should consider keeping a spare for replacement during the annual inspection, for prompt replacement if a problem is identified. 

Water Level Device

A water-level device controls the water volume inside the boiler. If it fails, you will need an operator to regulate a manual valve when necessary to keep the boiler close to its Normal Water Level (NWL). In this case, the best option is to have a spare water level sensing device on hand. There are many different types of water level controls, the specific devices that are on your boiler will determine the appropriate spare parts.

High Pressure/High-Temperature Cutout Switch 

The boiler temperature control switch in hot water boilers or pressure switch in steam boilers can halt operations when they fail. The device is relatively inexpensive, don’t let it slow down production.

Fuel Safety Shutoff Valves

Fuel safety shutoff valves are safety control equipment that prevents the flow of oil or gas into the boiler when it shuts down. Imagine what would happen when you light a boiler filled with fuel. The outcome would be hazardous, either an explosion or fire.  

Fuel Safety Shutoff Valves

Ensure that you have replacement closure switches and a rebuild kit for large valves. It’s also important to note that valve repair may be time-consuming. However, you should worry less if your boiler valves are inspected during your scheduled annual maintenance.

Combustion Air Switch

At some point, you have probably thought about what would happen if you light the boiler, but the fan fails to spin. Well, nothing would happen, all thanks to the combustion air switch. With this device, the burner cannot open the fuel valves without adequate airflow-this is reason enough to have a replacement part in your boiler room. 

High and Low Gas Pressure Switches

High and low gas pressure switches monitor for “out of range” gas pressure being delivered to your boiler’s burner.  If gas pressure is too high or too low, it can lead to nuisance trips or dangerous combustion issues.  The exact pressure switch used is determined by the operating pressure ranges for your boiler, spare stock switches should be selected to match these conditions.

high and low gas pressure switch

Boiler Gasket 

Boiler gaskets are replaced once per year or during boiler inspection. They are available in many different materials for different services (temperatures and pressures). 

Over time, with heating and cooling cycles gaskets can fail and allow leaks.  Gaskets are relatively affordable and cheap insurance against unexpected failures  – you will also be in a position to address downtime sooner when a leak occurs. 

We suggest having one to two complete sets of new handhole and manway gaskets plus a roll of fireside gasket rope or tape on hand. 

Boiler Level Sight Glass 

This device helps in identifying the actual water level in the steam boiler. If the sight glass or packing leaks, it will display wrong water level measurements leading to risky operating conditions. 

The importance of a clear and clean boiler-level sight glass cannot be over-emphasized. Blowing it down won’t work; instead, replace it with a new one.

Keeping a spare part in your boiler room makes switching it out easier if a problem arises. You should also replace the part at least once every year. Reusing worn-out components isn’t worth the risk. 

Valve Packing Sets

While it’s possible to run your boiler with leaking valve packing, it’s not right. Some operators tighten the packing to reduce leakage. Unfortunately, valves don’t work well when the packing is overtightened. Therefore, it’s reasonable to have extra packing sets for your valves. 

Observation Port Glass and Packing 

Operators need to check the flame regularly. However, the observation port glass and packing are often broken, sooty, hot, or leaking, making it impossible to have a clear view. 

If the damage is extreme, you might have to replace your old observation glass with a new one. That way, it will be easier to notice cracked refractory, spoilt burner, and spot leaks. A spare part comes in handy in such a situation. 

Gas Regulator

We suggest you keep a complete rebuild kit for your gas pressure regulator plus a manual. Otherwise, you may struggle to get one quickly when your system is down. It’s also good practice to inspect the vent lines to confirm that they are free from any blockages.

considerations when purchasing in house parts


The quantity and type of replacement parts you might need vary depending on the application. For instance, high-priority facilities like hospitals or manufacturing plants that cannot afford a boiler to be down require an in-house spare part stock of fuses, selected controls, heating elements, and gaskets. 

It is best to consider the cost of downtime, storage space, the shelf life of the parts, and storage cost before purchasing boiler spare parts. Although halting production is often expensive, it might still not be necessary to keep all spare parts on site. For instance, if your facility has a backup boiler, you may have more time to source parts and may only need to stock the longest lead-time items.  However, ensure that you can access emergency boiler repair during an outage. 

Are you in need of boiler parts or repair? Contact the W.C. Rouse repair team to get boiler room experts to find the best solution.  

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.