The Best Boilers For Fluctuating Load Demands

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The most common industrial boiler systems on the market are designed to provide consistent hot water and/or steam heat for a variety of applications. The downside is that many industries don’t need steam 24 hours a day, and these systems are not well-suited to accommodate changes in demand. The time between a cold start to steam may take hours, so once it’s up and running, you don’t want to power it down even when steam is no longer needed — resulting in lots of wasted fuel and higher energy bills. So how do you choose the best boiler system for the fluctuating load demands of your particular industry? Which is the right boiler for you?

To answer that question, let’s begin by discussing the importance of boiler design, explore the various types of boilers, and identify the best boilers for accommodating changes in demand for steam and/or hot water.

Best Boiler Brands Versus Best Boiler Design

Let’s be clear: Selecting the best boiler can be downright confusing. There are a wide range of boiler manufacturers out there, and boilers may also be used in a wide range of applications, from heating systems to heat pumps to water heaters. They may run on natural gas, heating oil, propane, LPG fuel or electricity. There are also residential boilers, commercial boilers and industrial boilers. Each boiler manufacturer will boast about the features of their products, claiming high-quality, energy efficiency, energy star ratings and more.

The truth is, while boiler brands are important, they are not as important as the type of boiler you’re looking at — specifically, how it’s designed and how it functions. It is the design, not the brand, that actually determines whether a boiler will respond to fluctuating load demands. Pay attention to the boiler manufacturer — but pay equal or more attention to how the boiler is made and how it produces hot water or steam.

Industries that Deal with Fluctuating Load Demands

At some level most industries will experience changes in demand for steam during the course of their workflow. For some industries, these changes in demand are more seasonal; they will run a steam boiler for long stretches of time, then power it down for a few weeks or even months because they don’t need it. For these industries, the type of boiler they choose might not be as critical.

However, for many industries and facilities, the demand for steam may fluctuate drastically during the course of a day. There will be peak times of day when usage is high, and other times when demand drops. It is these industries which are most likely to feel the pain of high energy bills even during non-productive times. Examples may include:

Smaller craft breweries and distilleries. Many of these facilities don’t run on a 24-hour work cycle
These may experience boosts in demand during high guest capacity, at meal times and when doing internal laundry, for example.
Educational facilities and hospitals. These may experience similar fluctuations as hotels.
Laundry facilities. Demand for steam goes up when loads come in.
Food processing facilities — especially smaller plants with shorter hours or where incoming orders fluctuate.
Any plant, factory, facility or industry seeing to improve energy efficiency and reduce their carbon footprint.

Common Types of Boiler Systems

Now that we understand that the design of a boiler system has the greatest impact on its ability to adapt to fluctuating demand, let’s look at the four most common types of boilers and how they measure up.

Fire Tube Boilers

The most common type of boiler system found in industrial settings is the conventional fire tube boiler. In this design, a set of tubes containing heated gas is submerged in a large water tank. These tubes serve as a heat exchanger to transfer the heat into the water, eventually causing it to boil and produce steam. Since water takes time to heat, this design is the least efficient for fluctuating loads because of the time it takes to produce steam and then cool down. Fire tube boilers also tend to have lower Annual Fuel Utilization Efficiency (AFUE) ratings, which is the ratio of how much heat transfers to the water versus how much goes out of the flue. Older fire tube boilers can have AFUE ratings as low as 50 percent, meaning only half the heat energy turns to steam heat and the rest is wasted. New boilers of the fire tube design are more energy efficient, averaging AFUE ratings around 80 percent or higher.

Modular Water Tube Boilers

It might be helpful to think of a water tube boiler design as the inverse of a fire tube boiler. Instead of the hot gases running through tubes immersed in water, the water runs through tubes surrounded by heat in the chamber on all sides via a “floating header” design. This “floating header” is critical because it allows the pipes to expand and contract freely in response to the cold water inside and the heat outside without the risk of thermal shock. This design requires less water, which can then be converted to steam more quickly, consuming far less fuel in the process while typically achieving an AFUE rating of 83-85 percent.

Electric Boilers

Electric boiler systems typically follow the same basic design as fire tube boilers in that the heating element is submerged in the water tank to heat the water. The primary difference is in the fuel being used — namely, electricity versus natural gas, heating oil, etc. Since electricity is a clean form of energy, electric boilers are prized for their energy efficiency and virtually no emissions, often achieving an AFUE rating near 100 percent. However, the difference in fuel type does little to improve the boiler’s ability to adapt to changes in demand since the tank/burner design is roughly the same. Additionally, while these boilers are highly efficient, the cost of electricity can be quite expensive by comparison, so these boilers do little to save on costs even though they represent a “greener” solution.

Condensing Boilers

Condensing boilers are high-efficiency boilers which are primarily valued for their energy savings. These boilers are designed with dual heat exchangers — the conventional tube in the water and a secondary exchanger that recycles waste heat from the flue back into the boiler. The residue heat helps pre-warm the feed water while the resulting condensate water vapor drains out through a pipe. This design helps condensing boilers achieve an AFUE rating of up to 99 percent, but it still does little to change steam output to accommodate fluctuating demands.

Which Boiler Type Is Best for Fluctuating Demands?

Among these four common boiler types, by a wide margin, the water tube boiler is far more adaptive to changes in demand than the other three. Water-tube systems can go from a cold start to producing steam within minutes, rather than hours, making them very responsive to changes in demand. In addition, their modular design enables multiple modules to be set up in tandem, allowing them to fire up and power down in direct response to demand fluctuations.

water tube boilers offer other benefits compared to conventional designs, as well. These include:

A compact, space-saving footprint. water tube boilers require less space, in part because they store less water at a time.
Higher safety ratings than conventional boilers. Fire-tube boilers in particular are susceptible to overheating and exploding; the water tube design makes this virtually impossible.
More energy efficiency. While other designs may have a higher AFUE rating, the water tube design still requires far less fuel to achieve steam — plus the steam-on-demand ability allows the burners to shut off more frequently, also consuming less fuel.

Miura Water Tube Boilers Offer Superior Advantages

Among the manufacturers of water tube boilers, Miura boilers have one of the best reputations especially among industries needing steam-on-demand abilities. Some of the reasons why:

Exceeding quality standards. Even among water tube boilers, Miura boilers are among the most efficient on the market.
Remarkably low NOx emissions. Miura boilers are designed to reduce emissions of harmful nitrogen oxides (NOx), making them an excellent choice for companies needing to meet emission standards or lower their pollution output.
Unmatched safety record. With hundreds of thousands of boiler units in operation, Miura boilers have never had an injury-producing accident.
Advanced monitoring and maintenance systems. Miura utilizes state-of-the-art self-diagnostic monitoring technology to identify and solve small problems before they become big ones.
Reliability backed by an industry-leading warranty. Miura offers a robust seven-year pressure vessel warranty with every unit sold.

Which Miura Boiler Is Right for Me?

Depending on your company’s needs, Miura boilers are currently available in LX or EX designs:

The Miura LX runs on natural gas and is our more compact design, perfect for companies with space limitations. For those concerned with emissions, the LX also boasts the lowest NOx emissions at about 9 ppm.
The Miura EX is our dual-fuel model, able to run on natural gas, propane or oil, making it an excellent choice for businesses requiring alternate fuel options. While less compact than the LX, it still occupies less space than a traditional boiler system while providing a comparable steam output.

Contact a Miura rep in your area or call us at 1-678-685-0929 to learn more about choosing the best boiler to meet your fluctuating load demands.