Managers need to evaluate a number of issues in order to make the most appropriate choice for their company.
By James Piper, PE
Boilers are one of the most important components in the HVAC systems of institutional and commercial facilities. They require significant investments in installation and maintenance and are one of the largest energy consumers in a system. In addition, the failure of a boiler during the heating season can lead to malfunctions and major damage to the system and its contents. It is therefore not surprising that maintenance and engineering managers need to pay special attention to the operation of the boilers in their facilities.
Like all system values, boilers have a limited service life. Even with the best maintenance, they will eventually have to be replaced. The challenge for managers is to find the turning point. Is it best to fix the existing boiler or is it time to invest in a new one? If you wait too long, the cost of servicing the boiler could become too high or the boiler could fail. However, replace it too soon and the money will be wasted.
To make the right decision about repair and replacement, managers need to understand the condition of their boilers. You also need to understand how these boilers serve the facility and the future needs of the facility. You can develop this understanding by carefully examining seven key factors in the cauldron.
1. Age: More than a number
While kettles are durable, they don’t last forever. Cast iron boilers, if properly maintained, have a typical lifespan of 30 years or more. Condensing boilers have a service life of 15-20 years, also provided that they are properly maintained. These areas do not mean that boilers always need to be replaced when they have reached their rated operating time. It is an indicator of the remaining life of the boiler, a factor that managers need to consider when deciding on repair and replacement.
The maintenance costs of the boiler increase as the boiler ages. Managers need to look at the trend line for servicing the boiler. If it’s shallow, even as the kettle nears or has passed its rated life, repair may be the best option. If maintenance costs are relatively high and increasing, replacement may be the best option.
When a boiler is nearing the end of its rated life and extensive repairs are required, the age of the boiler can be the deciding factor for a replacement. However, if it is a reliability problem, managers need to determine the cause or causes
2. History overview
A boiler’s operating history is another important factor managers must consider when making a repair-replacement decision. Frequent failures indicate that either something is wrong with the installation of the boiler or that it may no longer be reliable. If the problem is the installation, e.g. Due to improper piping, for example, technicians can fix the problem before managers consider replacing it.
Managers can also view the boiler’s maintenance records. Is the topic always the same or are new topics developing? Are the problems minor and easy to fix, or are they warning signs that the possibility of a fatal error is on the way? Look again at the trend line to see if the number of maintenance problems is constant or increasing. Increasing maintenance requirements mean increasing operating costs, a sign that the boiler is nearing the end of its effective life.
The biggest problem with frequent boiler failures is that they occur at the most inopportune time – in the middle of the heating season on what is usually the coldest night. If a boiler then fails, the building systems and their contents can freeze. If the damage is severe enough, it may be necessary to relocate operations to another facility during the repair. If the boiler has failed in the past, operations managers must weigh the risk of potential costly damage against the cost of replacing the boiler.
3. Cost Considerations
The availability of spare parts also affects a manager’s decision to repair or replace a boiler. Manufacturers do an excellent job of maintaining an inventory of replacement parts, but as they introduce new models, they gradually demote the inventory of replacement parts from older models. This can enable the technician to spend a lot of time looking for the required parts or to manufacture a replacement part while the boiler is at a standstill.
Many boiler repairs can be done with generic parts like valves and pressure gauges, but some require OEM parts. Managers need to take this into account when evaluating the repair-replacement decision. Will you be able to get what you need when you need it? If so, what will it cost?
Assuming technicians can source the parts they need, managers need to weigh the cost of repair against the cost of replacing the boiler. In most cases, the repair cost is only a small fraction of the replacement cost, so it makes sense to make the repairs you need.
But in some cases, such as when a major boiler overhaul is required, the repair cost can be a quarter to half the cost of a replacement boiler. In these cases, especially as the boiler nears its rated life, managers need to consider other issues to determine if the boiler is worth repairing.
4. Focus on efficiency
Lowering energy costs has long been a goal of managers. As boilers are one of the largest energy consumers in facilities, managers have accordingly turned their attention to boiler efficiency. It is natural that a boiler will become less efficient with age, even if properly maintained.
Wear parts. Scale slowly forms on the heat transfer surfaces. Repairs made in the past, even if done properly, can further reduce efficiency. Tests on a typical 30 year old boiler show an operating efficiency of 70 percent or less. A new condensing boiler can have an efficiency of 95 percent.
The energy saving potential that managers can achieve by replacing a boiler can make replacing an existing boiler worthwhile even when it is in good operating condition. But before making that decision, managers should analyze the future energy costs for each system for a typical year. Energy savings alone may not be enough to warrant replacement, but efficiency, along with other factors, can be enough to make the difference.
5. Safety headlights
Safety is important when evaluating a boiler for repair or replacement. Older boilers are most likely not in compliance with current safety and operating regulations, and while managers may not be required to upgrade an existing boiler to current requirements, safety is a factor when considering repair or replacement.
Technicians must regularly test all boiler safety devices to confirm that they are working properly. Managers must also consider working with a boiler specialist to assess the safe operation of an existing boiler. Based on the recommendations, managers can assess whether it is more appropriate to make changes to the existing boiler to improve safety or to install a new boiler that complies with applicable regulations.
6. Configuration problems
A typical boiler installation in a larger facility consists of one or two large boilers. Each boiler is dimensioned so that it can carry the heating load most of the time, and the other boiler serves as a backup. While this system works well for meeting the facility’s heating needs, it is not the most efficient configuration.
Boilers can adapt their firing rate to different loads. If the combustion output of a device falls below the minimum, it can happen that the boiler switches off temporarily. This cycle reduces operating efficiency and stresses the boiler components due to temperature fluctuations.
Boilers do not have to be exchanged for contributions in kind. Instead of one-to-one replacing a failed device, managers can consider installing several smaller boilers and setting them up so that additional boilers come on-line as the heating load increases. This strategy allows managers to more easily adjust the boiler capacity to the heating load, avoiding cycles and improving operational efficiency. Multiple smaller boilers also improve system reliability, as the failure of one unit does not significantly affect heating performance.
7. Technology talk
The innovation in boiler design is ongoing. Digital technology has replaced mechanical controls in new generation boilers, allowing technicians to remotely control boiler operations. Significant improvements in boiler design have resulted in higher operating efficiencies.
By considering these seven factors when evaluating the boiler repair replacement option, managers can make the repair or replacement decision from a position of understanding. You can better take into account the current and future needs of the plant, the condition of the existing boilers, the costs of further repairing the existing boilers and the costs of installing a new plant. By evaluating each factor, managers can determine the best option for their applications.
James Piper, PE, is a national consultant based in Bowie, Md. He has over 30 years of asset maintenance, engineering and management experience.