How A Water Tube Boiler Works

A water tube boiler runs off of water tubes that are heated externally by fire. The tubes connect to a steam drum and a mud drum, and steam is produced in the upper drum. The water in the tubes creates steam directly, instead of tubes heating water as is the case in a fire tube boiler. Water tube boilers are used more for industrial applications and less for heating purposes.

These types of commercial boilers are commonly used in larger facilities such as hospitals or universities. In general, they pose a lower risk of catastrophic failure due to the lower volume of water in the boiler.

How A Fire Tube Boiler Works

A fire tube boiler transfers heat through tubes via thermal conduction, which then heats the water in the container and formulates steam. In other words, the boiler is the pressure vessel that contains the water. These boilers are used in steam or hot water applications when they meet guidelines in ASME Sections I IV. A fire tube boiler can also be used to vaporize liquids other than water as well.

Fire tube boilers are ideal for both low and high-pressure steam, or for hot water applications. They are commonly used for applications that are not above 350 psi. They often range in size from 600,000 btu/hr to 50,000,000 btu/hr, but can also range from 500,000 btu/hr to 75,000,000 btu/hr. Fire tubes are easy to replace, so maintenance is simple for facilities that use this commercial boiler.

Comparing the Water Tube Boiler and Fire Tube Boiler

  • The water tube boiler can also handle higher pressure in applications that require more than 350 psi, unlike the fire tube boiler, which has greater pressure limitations.
  • The physical size of a water tube boiler unit can often be a deciding factor when choosing between a water tube or fire tube boiler, because these types of commercial boilers are typically smaller.
  • Water tube boilers have better efficiency ratings and generally drive lower fuel costs. They do cost more up front, however, and cleaning the unit can be difficult because of its design.
  • Fire tube boilers, on the other hand, are relatively less expensive, smaller in size and easier to clean though they have pressure limitations.

When choosing between a water tube or fire tube boiler, it’s best to consult a professional. Contact American Boiler Company today to see which commercial boiler is best for your facility. We can help take the guesswork out of selecting a commercial boiler and offer unrivaled industry expertise based on decades of hands-on experience.