Boiler Room Guide

Boiler Selection Considerations System Fundamentals

For more information on specific firetube boiler products, refer

to Section A.

Firebox boilers

The firebox boiler uses similar tube attachment techniques as

the firetube boiler. Its combustion chamber is not round, like

the firetube’s cylindrical furnace. The firebox boiler is typically

manufactured to low pressure steam or hot water applications.

The firebox boiler is a compact, economical unit and

serves as a good fit for seasonal use and when efficiency is not

the driving factor. Sizes range from 12 to 337 horsepower.

Commercial Watertube Boilers

Commercial watertube boilers typically produce steam or hot

water for commercial, or modest-size applications. There are a

wide variety of types, sizes, capacities, and design pressures

available. Commercial watertube boilers can be membrane

type, straight tube, modular, etc. They can be either atmospherically

fired or utilize power burners.

For more information on commercial watertube boilers, refer

to Section B.

Industrial Watertube Boilers

The industrial watertube boiler typically produces steam or

hot water primarily for industrial process applications, and is

used less frequently for heating applications. In the watertube

design, tubes contain steam and/or water and the products of

combustion pass around the tubes. Typically, watertube

designs consist of multiple drums. A steam drum (upper) and

mud drums (lower) are connected by the tubes, which form

both the convection section and the furnace area.

Packaged industrial watertube boilers are typically rated in

pounds of steam per hour output at operating conditions and

range from 10,000 to 134,000 lbs/hr.

Industrial watertube boilers are noted for their fast steaming

capability. Steam is generated very rapidly because of the relatively

low water content. This allows them to respond quickly

to changing load demands.

The industrial watertube boiler design makes it capable of

generating either saturated or superheated steam. When applications

dictate superheated steam usage, large or fluctuating

steam loads, or high pressures (greater than 350 psig), an

industrial watertube boiler should be considered.

For more information on industrial watertube boilers, refer to

Section C.

Flexible Watertube (Bent Tube) Boilers

Flexible watertube boilers are a common type of boiler used

for heating applications because of their resistance to thermal

shock. Flexible watertube boilers are available in size ranges

from 2 to 9 MMBtu/hr input. Flexible watertube boilers are

available for

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