Commercial firetube boilers are just one option for facility managers who are looking for efficient processing and heat servicing through hydronic and steam systems. Trying to select the best models for a given application is contingent on several factors, including space available, the type of water/steam required, efficiency requirements, and maintenance needs. Below, we’ve gone over some key factors to consider if you’re thinking of designing and/or purchasing a commercial firetube boiler.
The firetube boiler is one of the oldest designs; while many improvements have been made over the centuries, it still utilizes a fundamentally simple process: hot gasses pass through symmetrical tubes surrounded by water, thus allowing heat to transfer to the fluid that can remain in a liquid state (hot water) or gas state (steam).
As their names imply, the principal difference between watertube boilers and firetube boilers is whether the combustion gasses surround the water, or vice versa.
Firetube boilers are typically used in commercial settings and have a simpler design than watertube boilers. They are generally easier to inspect, maintain, and repair than watertube boilers.
However, each has their place. Water tube boilers are crucial for applications requiring high-pressure steam, like for cogeneration plants or large multi-building steam systems. They can handle large swings in demand for steam compared to watertube boilers.
In the same vein, however, they are less well suited for spikes in demand, whereas firetube boilers can accommodate brief changes in load. In addition, water impurities can have a significant impact on watertube boilers because of the lower content within the system and potential sediment accumulation.
There is, additionally, the option of using vertical firetube or tubeless boilers in areas where there is an extremely small footprint. These were first used back in the days of steam engines and steamboats, but still have their place in applications where a horizontal box cannot work within a building’s footprint. While they are quick to come into operation, there are often limits in terms of maximum hot water and steam generation due to dimensional limits.
One of the most common differentiating features in firetube boilers is how the combustion gasses are routed after their first pass through the tubes used to heat the water. Each model features a different type of reversal chamber.
The wet-, or water-back, system, has a reversal chamber that is completely submerged in water. They are often more efficient and smaller than their counterparts but can be more difficult to access for maintenance as it can be difficult to access the rear tube sheet.
The alternative is the dry-back system, in which combustion gasses are passed through the tubes and then through a reversal chamber that is lined with refractory. Its chief benefits are that maintenance can be easier since technicians can access fire and water-side components relatively easily. However, it can be less efficient, with energy lost through the refractory material rather than heat transferred to the water
There is a potential misconception among end users that going to condensing boilers is the only way to increase the efficiency of watertube and firetube boiler systems. In fact, using what’s called a feedwater economizer can be designed into the system and used with either watertube or firetube boilers.
Like a heat exchanger, the economizer works by taking exhaust gasses and passing them through a heat exchanger that transfers heat to the boiler’s feedwater. By raising the temperature of the feedwater, the overall energy required to bring it up to operating temperatures is lower, leading to efficiency improvements. While a firetube boiler provides thermal efficiency of roughly 80‒85 percent, systems using economizers can offer ranges of 87 to 91 percent.
Every building has different requirements and specifications, so it’s important to consult an HVAC expert before you choose the type of boiler you use. You’ll want to take your heating needs, your budget, and your occupants’ heating needs into account. Modern boilers must work in concert with the building’s hydronic or steam system.
Windy City Representatives works with leading manufacturers of commercial firetube boilers for HVAC systems. We understand how important it is to take multiple considerations like budget and existing systems into account when specifying these units. To discuss how we can help you find the best system for your needs, call us today at 630-590-6933.
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