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Boiler Basics 101: Economizers for Increased Efficiency

The price of fuel is constantly fluctuating and with it comes creative ways to be more economical. Finding methods to be more energy efficient is never a waste of time. In the boiler room, efficiency improvements can be found by many sources, however, a common option for energy savings includes the use of an economizer. What is an economizer? The economizer is a fabricated assembly of finned tubing that captures waste heat extracted from the boiler’s stack flue gases; the exhaust that leaves the boiler stack (or “flue”).

It’s all about the principle of Heat Transfer. While low temperature water, or feedwater, enters a boiler system, high temperature flue gas exits. An economizer captures heat from the flue gas that would typically go to waste, and utilizes it to preheat the feedwater. By doing this, an economizer is able to increase thermal efficiency by decreasing the energy required to heat the water to steam. This will typically result in a reduction of 1% in fuel cost per 10 degree rise in feedwater temperature. Overall, an economizer can be a major cost savings for boiler owners and will easily provide a quick return on investment.

The economizers’ simple technology and static parts provide longevity and low maintenance, and they are available in multiple designs and configurations. Conventional economizers are cylindrical or rectangular and come in a range of sizes for both firetube and watertube boilers. Rectangular designs are more commonly used for larger industrial watertube boilers, and can be configured for vertical or horizontal gas flows, finned or bare tube design, and other additional options if needed. A condensing economizer can improve waste heat recovery even further by cooling the flue gas below its dew point, reclaiming both sensible heat from the flue gas and latent heat by condensing the flue gas water vapor.

BOILER EFFICIENCY COMPARISON
  Combustion Efficiency at
4% Excess Oxygen
Stack Gas
Temperature
 Boiler  78% to 83% 350F to 355F
 Boiler with Standard Economizer  84% to 86%  250F to 300F
 Boiler with Condensing Economizer  92% to 95%  80F to 150F


When determining whether an economizer is ideal for your boiler equipment, the location of the economizer into stack is important. To ensure the most thermal recovery during the process, you need to make sure the economizer is installed as close to the furnace breach as possible. This will help avoid thermal loss and cooling.

At Nationwide Boiler, we offer our EconoStak economizer as an optional addition (or a standard addition in some cases) on our fleet of watertube rental boilers. The EconoStak consists of the economizer as well as all of the associated piping and structural supports required for very efficient and safe operation. In addition, we are a West Coast representative for E-Tech Heat Recovery Systems, a leading provider of economizers for new, replacement, and retrofit applications.

Contact Nationwide Boiler today to see if an economizer is the right option for you, and be sure to check out our previous Boiler Basics 101 blogs. We review various topics each month, so stay tuned for the next edition!

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Guest — aadax industry
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Monday, 09 December 2019 08:15
Guest — Emma
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Tuesday, 10 March 2020 08:02
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Air Permitting for Rental Boilers in California

With California having the most stringent emissions requirements in the country, it is important to be well versed on any and all rules and regulations when buying a new boiler or renting a temporary boiler. This is our final installment of the 3-part series on air permit compliance for boilers in California (be sure to check out part 1 and part 2 if you haven’t already).

Nationwide Boiler maintains a fleet of rental units that are sub-9 ppm NOx and pre-permitted for use in the SCAQMD. We take care of the bulk of the permit work saving our customers an exponential amount of time (no waiting for the application to be approved), and we pay for any processing fees. This allows for quick installation and start-up of a temporary boiler, which is extremely valuable in an emergency outage. The only requirement of our customer is the source testing of the equipment, if the source test is due. Most of these pre-permitted boilers require source testing on an annual basis, and the source test must be done at a job site within the county’s jurisdiction.

The SJVAPCD does not allow the pre-permitting of rental boilers, but they do have a program called the Temporary Replacement Emissions Unit (TREU) which can be utilized when a rental is needed  in a pinch. This program contains an application shield provision which allows renters to install a temporary boiler in place of an existing permitted boiler that is down for repairs without having to get a new permit for the rental boiler. In order to qualify for the TREU Program, the rental boiler being installed must have a heat input equal to or less than the unit it is replacing. Plus, it must not have the potential to produce more emissions than the current permit allows. There is a time limitation to this program; the temporary boiler can be on-site for a maximum of 180 days within a 12-month period.

If you are outside of the two territories listed above, don’t fret! Nationwide Boiler can assist with the permitting process as needed. In addition, utilizing a pre-permitted boiler in a location other than the SCAQMD does have its advantages and can help expedite the permitting process.

With our headquarters being located in California, it is important to us that we are up-to-date with emissions regulations throughout the state. And with other areas of the country starting to experience a similar push for emissions reductions, we have the expertise and experience to help. Nationwide Boiler is proud to take the lead in helping customers everywhere understand and comply with current and future air regulation standards.
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Enhancing BMS Safety with the use of PLC-based Controls

Combustion equipment safety is essential for the daily operation of facilities and safety of plant personnel. Safety protocols and mechanisms in industrial plants have improved drastically in the last century, but incidents still occur far too frequently. Because boiler systems are inherently dangerous, safety must be factored into the design of not just the boiler, but also the burner, combustion control, and the overall operation of the system.


The burner management system (BMS) is just one of many safety devices built into a boiler system, designed to control the combustion process from beginning to end in a safe and reliable manner. It monitors high and low gas pressure, the combustion air fan, combustion air, and water levels, in addition to monitoring safety devices and controlling the sequence of lighting the burner. If any issues arise related to pressure or water level, it will initiate closure of the shut-off valves. To automate these processes, PLC-based controls are often used as a BMS. PLC based BMS gives you much more flexibility, the ability to use analog input signals as limits, limit voting and the versatility to have almost unlimited safety limits.


A Programmable Logic Controller (PLC) is a robust computer utilized for industrial automation. Although a PLC doesn’t physically look like a typical computer, it incorporates the very same technology seen in computers and smart devices that we use every day. The PLC receives information from connected sensors or input devices, processes the data, and triggers outputs based on pre-programmed parameters. It consists of a power supply, a CPU (central processing unit), input and output cards, and communication cards. A programming device (often a laptop computer) is utilized for writing programs into the PLC and HMI (human machine interface) which provides a visual model of the system as a whole.


Compared to traditional technologies, a PLC-based system is easier to troubleshoot, more reliable, more cost-effective, and much more versatile. In addition, PLC-based controls provide added levels of safety for the burner management system and overall operation of your boiler. PLCs are built in compliance with NFPA 85 and SIL2 requirements at minimum and can be configured to meet SIL3 standards as well. Therefore, we are seeing boiler control panels being built or updated to PLC-based systems more than ever.


Pacific Combustion Engineering has extensive knowledge and experience in the design, build, and programming of PLC-based combustion control systems. If you are in the market for an upgrade or brand-new panel that incorporates PLC, give us a call and we will design a system that fits your unique process needs.

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Routine Maintenance Reminders

Routine boiler maintenance is imperative not only for safety, but also to sustain efficiency and reliability of your system. Being proactive rather than reactive is likely to increase the longevity of your boiler as well as help prevent incidents that can result in injuries, damage, or worse. Incorporating routine maintenance into your facilities day-to-day operations will prove its worth with a great deal of short- and long-term benefits.

There are certain maintenance tasks that should be performed daily, and others that should be performed periodically. Below we have provided a list of best practices to follow when putting together your routine boiler maintenance plan.

On a daily basis, you should track and keep a log of the following items:

  • Boiler pressure and temperature
  • Stack temperature, to determine operational efficiency (a well-tuned boiler should have a stack temperature range of 50 – 100 degrees above the steam or water temperature)
  • Gas pressure to the regulator, as well as downstream from it
  • Water quality and pH levels, to ensure you are meeting the recommended levels

Blowdown of the boiler (bottom blow) and water column should also be performed on a daily basis. In addition, you should observe boiler and auxiliary equipment daily to ensure proper operation and that there is no damage, leaks, or unusual behavior. 

On a weekly to monthly basis, it’s important to conduct additional visual inspections and observe the operation of certain components for areas that may need to be addressed. This includes:

  • Gauge glass
  • Fuel supply valves
  • Operating and modulating controls, water level controls
  • Flame scanner & burner flame pattern
  • High- and low-pressure switches, combustion air proving switch
  • Indicating lights and alarms

When it comes to the burner, you should inspect the valves, pilot tube, and diffuser thoroughly for any signs of wear that might call for a repair. Also, be sure to observe the entirety of the boiler system for potential hot spots (an indicator of deteriorated refractory) and again, be sure to keep an eye out for any leaks of fuel, water, or flue gas.

Lastly, there are certain items that should be performed on a semi-annual to annual basis. Many of the tasks below can be checked off during the annual inspection, when the boiler is taken offline:

  • Open access doors and inspect the fireside of the boiler
  • Inspect boiler and tubes for evidence of corrosion; clean tubes and tube sheets thoroughly
  • Examine the refractory for large cracks (greater than 1/8”) and patch as necessary
  • Conduct safety tests on the gas valves
  • Review all electrical connections for tightness, signs of wiring wear
  • Check pump alignment on all base-mount pumps

This is also a good time to fully inspect the auxiliaries that provide fuel, air, water, and chemicals to the boiler. In addition, combustion should be reset periodically with the use of a combustion analyzer, for accurate readings of NOx, CO, and O2.

While the guidelines above provide a good baseline of tasks to perform when it comes to routine maintenance, be sure to consider the boiler manufacturer’s recommendations as well.  

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