Watlow WATROD Duct Heater User Manual

WATLOW IND. WATROD Duct Heater (module only) I& M Manual

I&M NUMBER: 316-42-16-1 Page: 1
Date: 6/11/2008 Rev: 2.00

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Pre Installation

• Check to make sure that heater received is the same as that ordered.

• Elements may come in contact with each other during shipment. Minor adjustments to elements may be

required prior to installation to separate them. Extensive bending of elements should be avoided since
dielectric strength between coil and sheath may be compromised.

• Watlow heaters are built to comply with UL and CSA dielectric requirements, it may be necessary due to
atmospheric conditions / humidity, to perform a dielectric test prior to startup. (Refer to megohm test
under Installation section)

Safety

Electric heaters are inherently dangerous!! Care should be taken to read and completely understand the

Installation and Maintenance manual before installing and wiring the heater. Any installation and
maintenance performed on the heater shall be done by a qualified electrician, in accordance with the
"National Electric Code" and other electrical codes as they apply. It is the users responsibility to ensure that
the heater being used is properly selected and installed in the application.

The Caution Symbol (exclamation point) alerts you to a "CAUTION", a safety or functional hazard which
could affect your equipment or its performance.

The warning symbol (lightning bolt) alerts you to a "WARNING", a safety hazard which could affect you and
the equipment

Installation

Proper heater selection and installation will result in efficient heat transfer, safe operation, and long heater
life.

1. Megohm precheck

During shipping and/or storage, the possibility of moisture absorption by the insulation material within the

element is possible. To ensure proper megohm values a minimum 500 VDC megohm meter (Megger)
should be used to ensure that the megohm reading between the heater terminal and the heater sheath is
more than 10 megohms when the unit is at room temperature.

If several units are interconnected, the megohm of the heater is obtained by taking the reading and

dividing by the number of interconnected elements. This reading should be greater than 10 megohms.

If a low megohm value exists, two alternative methods can be used to remedy the situation. The best

method is to remove all terminal hardware, and bake out the heater at no higher than 250°F (120°C)
overnight or until an acceptable reading is reached. The second method is to energize the unit at low
voltage in air until the megohm is at an acceptable reading. Care should be taken to prevent the heater
sheath from exceeding 750°F (398°C) for Incoloy®.

2. Protection of heater elements from over temperature

The use of temperature controls to regulate heating process and prevent heater over temperature is

highly recommended to ensure safe heater operation. It is the users responsibility to ensure safety of
the installation. Individual heater modules are designed to accommodate optional high limit
thermocouple kit.

WARNING: Install high temperature control protection in systems where an over temperature
fault condition could present a fire hazard or other hazard. Failure to install temperature control
protection where a potential hazard exists could result in damage to equipment and property,
and injury to personnel.

WATLOW IND.n # 6 INDUSTRIAL LOOP RD. n HANNIBAL MO, 63401n PHONE [phone] n FAX [phone]

WATLOW IND. WATROD Duct Heater (module only) I& M Manual

I&M NUMBER: 316-42-16-1 Page: 2
Date: 6/11/2008 Rev: 2.00

_________________________________________________________________________________________________________________________________________________________________________________________________________________________
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Failure of components in a temperature control loop, such as the sensor, heater control relay or main

temperature control, can result in damage to a product in process, a melt down of a heater, and / or
damaging fire.

To protect against this possibility, over temperature protection must be provided to interrupt or remove

power from the heater circuit. A bulb and capillary thermostat is not recommended for this function

since it may not respond quickly enough to adequately protect the heater. In cases where the
thermostat bulb gets too hot before the system is turned off, the thermostat bulb could rupture.
This could result in the thermostat remaining in the "ON" condition since there is insufficient
fluid to move contacts apart. We recommend the temperature protection have appropriate third party

approval, and be applied in the classification for which it was tested and approved.

3. Terminal Enclosures

The product accompanying this manual does not come standard with a terminal enclosure. It is the

customer’s responsibility to provide a terminal enclosure that meets the safety and application
requirements of the specific application. An optional general purpose enclosure is available form the
factory if the user so desires.

Terminal enclosures should be designed to be compatible with the environment in which the heater will

be located. It is the users responsibility to determine the need for correct rating of the electrical housing.
This should be based on appropriate national and local electrical codes. Failure to use a compatible
enclosure could result in heater damage and personnel danger.

The optional terminal enclosure is designed for general purpose use and is rated NEMA 1. These

enclosures should be applied where there will be no danger of spilled liquids, dampness, dirt, and
gaseous conditions.

Units should be located in an area that will minimize the chance of being hit by falling or moving objects.

The terminals must be protected at all times from moisture or vapor.

In order to maintain termination integrity, the terminal enclosure should be kept below 400°F
(204°C).

4. Orientation / Mounting

An appropriate full scale cutout with dimensions for the heater module is attached. The duct heater may

be mounted vertically, or horizontally, from the left to right, top or bottom. The inlet side of the unit must
be at least 48" downstream from any transition in duct size or direction, or from any air handling
equipment. Care should be taken to properly support heater module to duct. A support plate can be used
to accomplish this. See Figure 1 for locations that should be avoided.

Heaters may be ganged in parallel for nearly any total wattage desired. The temperature control

thermocouple if so equipped should be located near the work to sense
process temperature sensing in the outlet stream away from the heater.

Minimum air velocity through the heater is 200 fpm for air temperatures approaching 800°F (412°C).

Lower velocities will jeopardize element life.

Air flow over the entire face of the heater should be uniform at the design velocity.
The units screw or bolt in place through the 9/32" dia. holes in the mounting flange. A 1/4-20 Allen head

exiting air temperature. Conduct

WATLOW IND.n # 6 INDUSTRIAL LOOP RD. n HANNIBAL MO, 63401n PHONE [phone] n FAX [phone]

WATLOW IND. WATROD Duct Heater (module only) I& M Manual

I&M NUMBER: 316-42-16-1 Page: 3
Date: 6/11/2008 Rev: 2.00

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OVERHEATING

OVERHEATING

Heater too close to transition

Heater blocked by filter and filter support

OVERHEATING

OVERHEATING

OVERHEATING

Heater too close to elbow

Figure # 1

WATLOW IND.n # 6 INDUSTRIAL LOOP RD. n HANNIBAL MO, 63401n PHONE [phone] n FAX [phone]

OVERHEATING

Heater too close to blower