TM 5-3895-374-24-2
HEATER MAJOR COMPONENTS
EXPANSION TANK: The expansion tank stores cooler heat transfer fluid which is not to be circulated. Tile
expansion tank is connected to the jacketed firebox via the exclusive CEI heat trap. This provides for
maximum life of the heat transfer fluid by keeping this non-circulating fluid’s surface temperature at a
minimum. Additional heat transfer fluid may be added to the system through the fill cap located on top of the
expansion tank. The Magnetrol Low-Level Control located on the burner end of the expansion tank will shut
down the heater if the level of heat transfer fluid drops below a desirable minimum.
BURNER:
The burner provides heat by burning
-light fuel oil only (oil units)
-natural gas or LP gas (gas units)
-light fuel oil or natural gas or LP gas (combination)
-heavy fuel oil only (heavy oil units)
Combination units have a fuel selector switch located in the panel box to facilitate switching from burning fuel
oil to gas or from burning gas to fuel oil. All CEI model heaters are equipped with a full modulation burner
monitored by a micro processor type control. With a standard 3:1 turn down ratio the burner modulates
through a continuous range of firing rates to match the heat demand of the system. Burner cycling is
minimized with an adjustable modulation band width in the temperature controller.
JACKETED FIREBOX: Combustion from the burner occurs in the firebox. The hot gases caused by
combustion must pass twice through the firebox before exiting through the heat exchanger, which is located at
the same end of the firebox as the burner. The firebox jacket contains flow control rings, which force the heat
transfer fluid to circulate around the entire firebox, thereby increasing heat transfer efficiency and eliminating
hot spots. The thermal or heat transfer resistance which exists between the combustion gases and the heat
transfer oil is minimized This is accomplished by using materials which have a high thermal conductivity and
optimum thicknesses which do not compromise on the structural integrity of the firebox. The firebox heat
transfer surface area is fully utilized leaving no direct heat sinks to the atmosphere as found in internal helical
coil designs.
HEAT EXCHANGER. Combustion gases in the firebox exit the firebox through the heat exchanger. These
gases travel inside a set of densely packed boiler tubes (Due to the close packing of the tubes, roughly 50% of
the heater’s total heat transfer surface area is achieved within the heat exchanger). The heat transfer oil
passes on the outside of these tubes in a multi-pass positive forced flow pattern. Extremely high forced
convection heat transfer coefficients arm experienced in the heat exchanger by maintaining high oil flow
velocities in each pass of the flow pattern. Automated welding
page 3-909
