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INSTALLATION, OPERATING &
MAINTENANCE INSTRUCTIONS FOR
350 SERIES CIRCULATION HEATERS
GENERAL
INDEECO Circulation Heaters are designed to provide
years of trouble free operation if properly installed and
maintained. Please read and follow these instructions for
installing and maintaining the heater.
Circulation Heaters are welded pressure vessels with inlet
and outlet connections to allow fluid flow and heat transfer
to a customer fluid. An Immersion Heater with tubular
electric resistance elements is used to provide heat.
Vessels 3” and larger utilize ANSI flange mounting. 2 ½”
and smaller are constructed with a pipe plug. Refer to
instruction manual 72-2010-83 for details on Flanged
Immersion Heaters and Pipe Thread Heaters. Instructions
for Industrial Control Panels are provided in 87-2000-83.
For additional product offerings, refer to INDEECO catalog
literature on Circulation Heaters, Immersion Heaters, or
Tubular Heating Elements.
ASME certified and stamped pressure vessels can be
supplied by INDEECO when specified.
A variety of designs and sizes are available with outlet
temperatures up to 1200qF. Due to these high
temperatures, the heater design features must be closely
matched to the application.
The heating elements are available in various watt density
ratings. Outlet temperature, watt density and flow velocities
determine the element surface temperature. Life
expectancy of the heating element is directly related to its
surface temperature.
INSTALLATION
INDEECO recommends installation be performed by
qualified personnel familiar with the National Electrical
Code and all local codes and standards. It is the
responsibility of the installer to verify the safety and
suitability of the installation
DO NOT mount heaters in an atmosphere containing
combustible gases, vapors, dusts, or fibers unless properly
marked as suitable for the condition. Refer to section
below for special instructions for Hazardous Areas.
Hazardous voltages are present in this equipment. Lock
out and tag the branch circuit disconnect switch before
working on this heater.
CAUTION
WARNING
WARNING
Failure to follow INDEECO recommendations could
result in premature failure and/or serious equipment
damage.
Temperature regulating devices, temperature limiting
controls, low liquid level, or low flow controls are
recommended for use with circulation heaters to control the
heating process and safeguard the heater from excessive
temperatures that can cause damage. Also on liquid
systems, damage to fluid could occur if the heater is
allowed to exceed the maximum film temperature
recommended by the manufacturer.
INDEECO 350 Series Circulation Heaters can be specially
designed for use in hazardous areas as specified in Article
500 through 516 of the National Electrical Code. Refer to
the heater nameplate or INDEECO Application Data for
classification of the heater provided. See section below
labeled Hazardous Areas for specific requirements.
It is the ultimate responsibility of the user to verify that
the construction materials provided in the INDEECO
Circulation Heater are suitable for use with the process
fluid. Specifically, corrosion issues must be reviewed.
Refer to INDEECO Application Data for heater
construction materials and design conditions.
Handling and Storage
Care must be taken to avoid damage to the heater during
storage and handling. Most heaters are provided from the
factory with insulation. The insulation is covered with light
gauge sheet metal jacketing which can be easily damaged.
Large horizontal vessels are normally provided with lifting
lugs to assist with movement.
Protect the heater from weather damage during storage if
shipping packaging is not sealed.
It is recommended to store the heater in a cool dry area to
help prevent the heating elements from drawing moisture.
CAUTION
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Mechanical Instructions
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Site Selection
Review the NEMA Type rating of the heater noted on the
INDEECO Application Data. Do not install a heater in an
area not consistent with its rating.
Allow sufficient free space around heater installation site.
Work space for heater maintenance should be at least three
feet in front and on either side of the heater. The minimum
pull space for the Immersion Heater installation or removal
from the vessel should be at least equal to length between
the inlet and outlet nozzle plus
Electric heaters are capable of developing high
temperatures. Therefore, extreme care should be taken to
avoid mounting heaters in an atmosphere containing
combustible gases, vapors, dusts, or fibers unless properly
marked as suitable for the condition.
Heater Orientation
This heater has been constructed for a specific mounting
orientation. It must be mounted in this manner, to prevent
improper operation or damage. Refer to the INDEECO
Application Data for the correct mounting figure number.
The location selected must be capable of safely supporting
the heater’s weight plus the fluid weight.
Mount the heater with structural quality bolts matching the
holes provided in the mounting feet. When Figure 23
(Vertical Floor Mounting) is provided, the mounting
channels must be drilled by the user. Where slotted holes
are provided, install the bolts to the outside of the slots to
allow the heater to thermally expand. Mount on a smooth
surface. Do not use lock washers, and apply minimum
torque necessary to contain the equipment but not prevent
expansion on bolts in slotted holes.
The heater should be mounted plumb horizontally and
vertically to assure proper flow and avoid draining or venting
problems.
Pipe the incoming fluid connection to the nipple marked
"Inlet". Pipe the hot outgoing connection from the nipple
marked "Outlet". The inlet and outlet references on the
attached figures are shown as the INDEECO standard
arrangement. The actual markings on the heater may be
reversed. Do not operate the heater with a flow direction
different from the nozzle markings without approval from
INDEECO. The heater may include instruments that will not
operate properly if the flow direction is reversed.
Note that customer piping must be supported to minimize
nozzle loading on the heater inlet and outlet. Consider
using expansion joints or flex hoses to allow connections at
the slotted end of the heater to move with the heater.
Failure to do so may result in damage or leaking of the
heater vessel.
two feet.
Thermal expansion of the heater can be approximated as:
Nozzle to
Nozzle length
(Inches)
x .00001 x
Operating
Temp (qF)
With liquid systems, the customer piping must be routed
and piped to ensure proper venting of the heater. Trapped
pockets of air will result in improper operation and potential
heater damage. High points must be vented and low points
drained to allow equipment maintenance. A low point drain
plug is provided in the heater to allow draining.
The heater is designed for operation at specified design
flows. When flow rates are not defined, the general
requirement is to limit flow velocity to 10ft/sec for liquids or
keep the density (#/ft
3
) x velocity (ft/sec) <10,000 for gases.
Customer piping size should match the inlet/outlet of the
heater to meet this requirement unless otherwise noted.
If the heater is installed in a pressurized system, a relief
valve must be installed at the outlet of the heater. A
pressure relief valve may be sufficient, unless local codes
require a pressure-temperature relief valve. As a minimum,
the valve must be sized to relieve at a rate equal to the rate
that the heater can thermally expand fluid trapped in the
heater due to downstream blockage.
DO NOT place a shutoff of any type between the pressure
relief valve and the heater, or on discharge pipes between
the relief valve and the atmosphere.
On heaters with ANSI flanged inlet/outlets, take care to
prevent scratching the flange faces. Select a gasket rated
for the application service and temperature and pressure.
Clean and flush system prior to initial startup to remove
contamination generated during fabrication. Provide filters
or strainers on liquid systems as required.
Insulation
Some surfaces of the heater vessel or Immersion
Heater may be extremely hot. Avoid contact to prevent
ersonnel injury or fire.
WARNING
Insulation is typically provided only on the heater shell by
INDEECO. The customer may prefer to add additional
insulation to the Immersion Heater flange or bottom head of
the vessel for added personnel safety and energy
conservation.
On heaters with extended terminal boxes and exposed
element tubes, do not insulate more than 2” above the
Immersion Heater flange. Dangerous over-heating of
the terminal box wiring could result.
WARNING
Insulation used on heating systems with flammable liquids
should utilize closed cell insulation to reduce fire hazards
caused by absorption of leaks.
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- 70qF
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Electrical Instructions
The potentially high operating and ambient temperatures of
Circulation Heaters require field wiring to the heater to be
carefully matched to the application to avoid serious injury
or damage to the equipment. The wiring must be de-rated
for the expected terminal box temperature.
The size and type of incoming field wiring will depend upon
the heater terminal box temperature, heater current draw
per conductor, number of conductors per conduit, and wire
insulation rating. Refer to the National Electrical Code.
The terminal box temperature is a function of the process
fluid temperature at the terminal box end of the heater. For
liquid systems, the terminal box temperature can be
estimated to be equal to the fluid temperature minus 50qF.
For gases, use the temperature of the gas. Extended
terminal boxes are provided on high temperature heaters to
allow moisture seals on the heating elements, and to avoid
costly high temperature wire. Refer to the Application Data
for the INDEECO estimated terminal box temperature.
Field supplied conductors must be sized for at least 125%
of the circuit current.
To calculate the circuit current (in amps):
KW x 1000 Single phase
Line current Line Voltage
KW x 1000 Three phase
Line current 1.732 x Line Voltage
Wiring to the heater should be permanently installed in
metallic or non-metallic electrical grade conduit in
accordance with all applicable electrical codes, and should
include a grounding conductor if non-metallic conduit is
used.
Field supply wiring must be rated for 600Vac. Use copper
conductors.
The electrical installation should include a service
disconnect switch in sight of the heater as well as branch
circuit over-current protection and over-temperature
protection (if not provided with the heater).
Refer to the wiring diagram included with this instruction
sheet for wiring recommendations. An additional copy is
provided inside the heater terminal box.
Where thermocouple extension wire is required between the
heater and control panel, verify it is connected with proper
polarity as shown on the wiring diagram. Failure to do so
may result in an uncontrolled heater. Refer to the wiring
diagram for the required wire type. Shielded wire is
recommended to reduce signal interference.
Retighten all electrical connections that may have
loosened during shipment. Failure to do so may result
in damage to the heater or risk of fire.
Confirm all unused conduit holes in the terminal box are
sealed with plugs suitable for the heater environment.
Attach a ground conductor to the stud located in the heater
terminal box or by other appropriate means per NEC Article
250.
Be sure the terminal box cover is properly installed at all
times to ensure personnel protection. Also, contaminants
can create leakage, (shock) hazards, permanent heater
damage or failure and should be avoided.
It is recommended to perform an insulation resistance test
prior to energizing the equipment. If the value is less than 1
Meg Ohm using a 500Vdc or similar tester, refer to
Maintenance and Troubleshooting sections.
WARNING
DO NOT TURN ON HEATING ELEMENTS UNTIL
TANK IS COMPLETELY FULL OF FLUID.
Permanent damage may result if elements are
energized when heater is dry.
This heater is designed to operate only up to
the maximum pressure and temperature as
shown on the name
To operate this heater, ensure the tank is completely filled
with fluid, start circulating pump, and energize the main
WARNING
WARNING
late.
OPERATION
supply disconnect. Set the controlling device to the desired
temperature.
During initial heating, it is recommended to slowly ramp up
the process set point and inspect the heating system for
problems.
DO NOT operate heaters at voltages in excess of that
marked on the heater. Excess voltage can shorten heater
life or overload the branch circuit wiring.
DO NOT operate heaters at sheath temperatures higher
than the recommended maximum. Excess temperatures
can cause premature failure. Generally, sheath materials
are limited to the following maximum temperatures.
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Sheath
Material
Copper
Steel
Stainless Steel 304
Incoloy 800
Maximum
Sheath Temperature
350q F
750q F
1400q F
1600q F
DO NOT operate heaters at flow rates below the design
flow range. Reduced flow can shorten heater life, cause
nuisance tripping of thermal safeties, or potentially exceed
vessel shell design temperatures. Note that heaters with
SCR control can typically operate at reduced flows down to
th
1/10
of the design flow if the controller is properly tuned,
and over-temperature safety devices are set at an
appropriate point to protect the heater and fluid.
INDEECO recommends that all safety interlocks are tested
during initial startup to ensure they properly disable the
heater. After 10 days of operation, retighten all electrical
connections.
On Flanged Immersion heaters, re-tighten heater flange
bolts after the heater has completed one or two heating
cycles.
Troubleshooting and repairs should only be
attempted by qualified maintenance personnel.
CAUTION
Periodically check all electrical connections, including field
and factory-made connections for tightness, and all wiring
for deterioration at least once a year.
Periodically inspect for leakage and retighten Immersion
Heater flange bolts when required.
Inspect the terminal enclosure and conduit connections for
evidence of water leaks or moisture collection. Tighten
connections as required. Clean up any corrosion. Do not
continue using a heater with signs of damage.
Where the heater is installed in cold climates, consider
safety precautions to prevent damage due to freezing fluid
when the heater is not in service.
TROUBLESHOOTING
MAINTENANCE
Troubleshooting and repair should only be
attempted by qualified maintenance personnel.
The nature of the magnesium oxide used to electrically
isolate the nickel chromium resistance wire in the heating
elements is such that over a long period of storage, they will
absorb considerable moisture from the atmosphere unless
hermetically sealed. It is recommended to perform an
insulation resistance test prior to energizing the equipment.
If the value is less than 1 Meg Ohm using a 500Vdc or
similar tester, care must be taken to dry out the heater to
prevent failure. It is recommended that the elements be
turned on at a reduced voltage at first to boil off the
moisture. Meg Ohm readings may drop initially after a few
minutes of operation, indicating moisture being forced out of
the elements. The terminal enclosure lid should be left
open during this period to allow the moisture to escape.
CAUTION
Where buildup of solids on the heating elements or
significant corrosion is expected, periodically remove the
Immersion Heater to inspect the vessel and heating
elements. Do not continue using a heater with signs of
damage. Before removing, note the orientation of the
flange or pipe plug relative to the vessel. Place a reference
mark on the vessel and Immersion Heater or use other
methods, such as drawing a sketch showing the conduit
hub orientation, to ensure proper orientation when reinstalling.
Immersion Heaters with cross-baffles or overtemperature thermocouples are specifically oriented
to match the vessel. Do not rotate the Immersion
Heater without consulting with the factory.
CAUTION
If the heater has a manual-reset high limit thermostat, be
sure that the reset button is pressed in.
The heating elements are not field-repairable. The only
recommended field repairs are to remove and replace the
faulty Immersion Heater, or to return the heater to the
factory for repair. Refer to instruction manual 72-2010-83 or
70-2010-83 for details on the Immersion Heater.
If reduced heat output is suspected, verify the condition of
the heating elements by using an ammeter to check the
current draw of each input line. All input lines should draw
approximately equal current, which should agree with
nameplate rating. If they do not, one or more of the heating
elements could be damaged.
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HAZARDOUS AREAS
INDEECO strongly recommends installation be performed
by qualified personnel familiar with the National Electrical
Code and all local codes and standards regarding
explosion-proof equipment. It is the responsibility of the
installer to verify the safety and suitability of the
installation.
WARNING – Explosion Hazard
Per Article 500-516 of the National Electrical Code, a
hazardous area is defined by a “Class”, “Division”, “Group”,
and “Temperature Code”. The Class can be I or II, where
Class I indicates that the hazard classification is due to the
presence of an explosive vapor. Class II indicates an
explosive dust. The Division can be either 1 or 2. Division
1 indicates a hazard is ALWAYS considered to be present.
Division 2 means the hazard is only present under abnormal
conditions. The Group defines the explosiveness of the
hazard. The Temperature Code specifies the temperature
at which a hazard will ignite.
INDEECO can provide designs suitable for all of the above
conditions, but a heater should never be placed in an
environment not noted on the heater nameplate.
NEVER operate the heater in an atmosphere with an
ignition code temperature LOWER THAN the nameplate
rating. The user must determine the actual area
classification.
Special design considerations for electric circulation heaters
used in hazardous locations:
1. Locate all electrical connections in an appropriate
enclosure.
2. Prevent surface temperatures of the heater from
exceeding the design ignition temperature.
INDEECO Circulation Heaters designed for Division 2
locations are provided with Nema Type 4 enclosures unless
otherwise specified, since the terminal box is free of arcing
or sparking devices. Heaters designed for Division 1
atmospheres are provided with an enclosure designed to
contain an explosion.
When the design temperature of the process exceeds the
rated ignition temperature, it is critical that the heater and all
customer piping is properly insulated.
Phone: (314) 644-4300 Fax: (314) 644-5332
(where applicable)
A hazardous area heater must be powered and controlled
by a heater control panel designed to provide necessary
over-temperature safety interlocks. Contact INDEECO if
assistance is required to properly control and protect the
heater.
Never apply power to a heater in a hazardous atmosphere
unless all terminal box covers are properly installed with all
cover bolts.
All conduits entering the heater terminal box must be sealed
within 18” of the heater using an explosion-proof conduit
seal. Any unused openings must be properly sealed with a
steel pipe plug. Follow the NEC for specific conduit
requirements such as the requirement for Rigid Conduit.
To ensure proper flamepath, all threaded conduits must use
rated fittings and be tight, with a minimum of 5 good threads
engaged. Any machined metal-to-metal surfaces on
terminal boxes must be handled carefully to prevent
scratches which may void the explosion-proof rating.
Operating the heater at a voltage higher than the
nameplate value may result in elevated
temperatures and amperage above the design
ratings.
Heaters used to heat explosive products such as methane
at a temperature above their ignition temperature must
remain free of oxygen.
Proper grounding of equipment in hazardous areas is
critical to eliminate potential sources of sparking.
Replacement of electrical components should only be done
by authorized personnel familiar with the requirements of
maintaining electrical equipment in an explosion-hazard
area.
INDEECO
425 Hanley Industrial Court
St. Louis, MO 63144
www.indeeco.com
WARNING - Risk of Explosion
35-2150-83-4
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Standard Circulation Heater Mounting Options
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