Watlow Brand Logo
  • English
    • 中文
    • Deutsch
  • Products & Services

    Products & Services

    Products Services Configure a Product Part Lookup Help Me Choose Product Documentation
    Products
    View All

    Electric Heaters
    Cartridge Insertion Heaters Circulation Heaters Immersion Heaters Air Heaters Flexible Heaters Tubular Heaters Gas Delivery and Exhaust Heaters High-Temperature Heaters Specialty Heaters View All
    Temperature & Process Control
    Multi Loop Controllers Single Loop Controllers Indicators and Alarms Limits and Scanners Operator Interfaces
    Power Control
    Power Controllers Power Switches
    Data Management
    Data Recorders
    Panels & Systems
    WATCONNECT® Control Panels POWERSAFE™ Thermal System
    Sensors
    Thermocouples Resistance Temperature Detectors (RTDs) Fiber Optic Sensing
    man with dual monitors using product selection assistant
    Not Sure? Try Our Digital Product Assistant

    Take the complexity out of product selection with our innovative Digital Product Assistant. Answer a few application questions and our interactive tool will recommend a product from our catalog.

    Launch Assistant
    Services

    thermalwatch thumbnail image of laptop with modern analytics dashboard
    THERMALWATCH™ Intelligent Analytics Solution

    THERMALWATCH leverages our deep understanding of thermal systems to provide secure data integration and management, along with expert analysis, to transform data into valuable information.

    Learn More
    Configure a Product

    vd_
    Watlow SELECT® Visual Designer™

    Quickly configure a product to meet the unique requirements of your application. Instantly access lead times, dimensional drawings, and more - at your own pace. No login required.

    Get Started

    Prefer to talk to a human? Find a Distributor or Sales Office 

    Part Lookup

    Know Your Part Number?

    Enter your part number exactly as marked.

    #
    Tip

    Many parts have lead times, dimensional, drawings, and more available on-demand. Click "Request a Quote" on the search result to access.

    Help Me Choose

    man with dual monitors using product selection assistant
    Not Sure? Try Our Digital Product Assistant

    Take the complexity out of product selection with our innovative Digital Product Assistant. Answer a few application questions and our interactive tool will recommend a product from our catalog.

    Launch Assistant
    Still need help? Locate a Rep Contact Us
    Product Documentation

    Watlow Catalogs Specification Sheets User Manuals Software and Demos Brochures
    CAD Drawings Mobile Applications Watlow Patents Certifications & Approvals
    catalog-ebook
    Try Our Interactive Catalogs

    Click Here

    Products
    View All

    Electric Heaters
    Cartridge Insertion Heaters Circulation Heaters Immersion Heaters Air Heaters Flexible Heaters Tubular Heaters Gas Delivery and Exhaust Heaters High-Temperature Heaters Specialty Heaters View All
    Temperature & Process Control
    Multi Loop Controllers Single Loop Controllers Indicators and Alarms Limits and Scanners Operator Interfaces
    Power Control
    Power Controllers Power Switches
    Data Management
    Data Recorders
    Panels & Systems
    WATCONNECT® Control Panels POWERSAFE™ Thermal System
    Sensors
    Thermocouples Resistance Temperature Detectors (RTDs) Fiber Optic Sensing
    man with dual monitors using product selection assistant
    Not Sure? Try Our Digital Product Assistant

    Take the complexity out of product selection with our innovative Digital Product Assistant. Answer a few application questions and our interactive tool will recommend a product from our catalog.

    Launch Assistant

    Services

    thermalwatch thumbnail image of laptop with modern analytics dashboard
    THERMALWATCH™ Intelligent Analytics Solution

    THERMALWATCH leverages our deep understanding of thermal systems to provide secure data integration and management, along with expert analysis, to transform data into valuable information.

    Learn More

    Configure a Product

    vd_
    Watlow SELECT® Visual Designer™

    Quickly configure a product to meet the unique requirements of your application. Instantly access lead times, dimensional drawings, and more - at your own pace. No login required.

    Get Started

    Prefer to talk to a human? Find a Distributor or Sales Office 

    Part Lookup

    Know Your Part Number?

    Enter your part number exactly as marked.

    #
    Tip

    Many parts have lead times, dimensional, drawings, and more available on-demand. Click "Request a Quote" on the search result to access.

    Help Me Choose

    man with dual monitors using product selection assistant
    Not Sure? Try Our Digital Product Assistant

    Take the complexity out of product selection with our innovative Digital Product Assistant. Answer a few application questions and our interactive tool will recommend a product from our catalog.

    Launch Assistant
    Still need help? Locate a Rep Contact Us

    Product Documentation

    Watlow Catalogs Specification Sheets User Manuals Software and Demos Brochures
    CAD Drawings Mobile Applications Watlow Patents Certifications & Approvals
    catalog-ebook
    Try Our Interactive Catalogs

    Click Here

  • What We Do

    What We Do

    The Thermal Loop Industry Solutions Electrification Industry 4.0
    The Thermal Loop
    Learn More

    icon representing a thermal loop system
    The Thermal Loop

    For Watlow, the underlying concept behind everything we do is that of the thermal loop. Every product we offer, and every project we work on, is ultimately about the creation and control of a thermal loop in an application. 

    Learn More
    Industries

    Heat Treatment Energy and Environmental Technologies Life Sciences
    Clinical Equipment Semiconductor Processing Foodservice Equipment
    Electrification

    thumbnails of white papers relating to electrification and decarbonization
    Electrification

    Over 100 years ago, Watlow began designing and manufacturing electric heating elements to replace steam in the shoe industry. We've been electrifying equipment and processes ever since. Wherever thermal is critical, no one is better equipped to help you reach your energy transition goals. Learn why leading companies partner with us.

    Learn More
    Industry 4.0

    thumbnail of industry 4.0 white paper on tablet and print
    The Thermal Loop & Industry 4.0

    Industry 4.0 technology enables the capture and processing of data in real time, both where its generated and where it is needed, to implement effective improvements to industrial processes. Capturing data, though, is not enough. The advantage Watlow® brings to an Industry 4.0 project are its thermal experts, who understand both the important role thermal loop systems play in key applications and industry 4.0 implementations.

    Learn More

    The Thermal Loop
    Learn More

    icon representing a thermal loop system
    The Thermal Loop

    For Watlow, the underlying concept behind everything we do is that of the thermal loop. Every product we offer, and every project we work on, is ultimately about the creation and control of a thermal loop in an application. 

    Learn More

    Industries

    Heat Treatment Energy and Environmental Technologies Life Sciences
    Clinical Equipment Semiconductor Processing Foodservice Equipment

    Electrification

    thumbnails of white papers relating to electrification and decarbonization
    Electrification

    Over 100 years ago, Watlow began designing and manufacturing electric heating elements to replace steam in the shoe industry. We've been electrifying equipment and processes ever since. Wherever thermal is critical, no one is better equipped to help you reach your energy transition goals. Learn why leading companies partner with us.

    Learn More

    Industry 4.0

    thumbnail of industry 4.0 white paper on tablet and print
    The Thermal Loop & Industry 4.0

    Industry 4.0 technology enables the capture and processing of data in real time, both where its generated and where it is needed, to implement effective improvements to industrial processes. Capturing data, though, is not enough. The advantage Watlow® brings to an Industry 4.0 project are its thermal experts, who understand both the important role thermal loop systems play in key applications and industry 4.0 implementations.

    Learn More
  • Who We Are

    Who We Are

    About Us Core Values Sustainability News Events & Webinars
    About Us

    We solve the world's toughest and most important thermal problems.


    About Us Leadership Team Company History Watlow Worldwide
    Core Values

    core values compass
    The Watlow Way

    At Watlow, our lean journey, as well as our core organizational beliefs are aligned with the Watlow Way, a set of core principles, behaviors and values which guides our company and is woven through every decision we make.

    Learn More
    Sustainability

    sustainability graphic - green earth
    Some of our best work is performed in areas intended to protect and preserve our environment

    We believe protecting the environment is everyone's responsibility and both our products and our own lean manufacturing processes are designed to address these challenges.

    Learn More
    News

    Find the latest news, press releases and annoucements.


    News
    Shiyi Zhou Joins Watlow® as Regional President for Asia Watlow® Welcomes Klaus Aarestrup as New Regional President of Europe Watlow’s New Large and Extra Large WATCONNECT® Control Panels Maximize Process Uptime with a Small Footprint Watlow’s New PM PLUS® 1/8 DIN PID Controller Watlow® Obtains KGS Certification on Flange and Circulation Heaters Watlow® Completes Acquisition of Eurotherm®
    View All News 
    Events

    Watlow & Eurotherm tradeshow booth at SPS 2024
    Events & Webinars

    Stay connected with Watlow through a variety of events, including upcoming trade shows, webinars, corporate and community involvement activities.

    Learn More

    About Us

    About Us Leadership Team Company History Watlow Worldwide

    Core Values

    core values compass
    The Watlow Way

    At Watlow, our lean journey, as well as our core organizational beliefs are aligned with the Watlow Way, a set of core principles, behaviors and values which guides our company and is woven through every decision we make.

    Learn More

    Sustainability

    sustainability graphic - green earth
    Some of our best work is performed in areas intended to protect and preserve our environment

    We believe protecting the environment is everyone's responsibility and both our products and our own lean manufacturing processes are designed to address these challenges.

    Learn More

    News

    News
    Shiyi Zhou Joins Watlow® as Regional President for Asia Watlow® Welcomes Klaus Aarestrup as New Regional President of Europe Watlow’s New Large and Extra Large WATCONNECT® Control Panels Maximize Process Uptime with a Small Footprint Watlow’s New PM PLUS® 1/8 DIN PID Controller Watlow® Obtains KGS Certification on Flange and Circulation Heaters Watlow® Completes Acquisition of Eurotherm®
    View All News 

    Events

    Watlow & Eurotherm tradeshow booth at SPS 2024
    Events & Webinars

    Stay connected with Watlow through a variety of events, including upcoming trade shows, webinars, corporate and community involvement activities.

    Learn More
  • Resources

    Resources

    Product Documentation Tools and Calculators Customer Service Knowledge and Insights CMRT/EMRT & Russian Material Disclosure Events & Webinars
    Product Documents

    Watlow Catalogs Specification Sheets User Manuals Software and Demos Brochures
    CAD Drawings Mobile Applications Watlow Patents Certifications & Approvals Retrofit Guides
    Tools and Calculators
     

    Wattage Calculator Ohm's Law Calculator 3-Phase Delta / Wye Calculator Glossary Equations Reference Data
    Customer Service Documents

    Invoice Payment Options Supplier Requirements Environmental Polices and Statements Copyright and Trademark Information Certifications & Approvals Policies Return Materials Authorization (RMA)
    Knowledge and Insights

    thumbnails of white papers relating to electrification and decarbonization
    White Papers
      Browse White Papers
    Tech Tips logo
    Tech Tips
      Browse Articles
    CMRT/EMRT & Russian Material Disclosure
     

    Conflict/Extended Mineral Russian Material Disclosure [.PDF]
    Events

    Watlow & Eurotherm tradeshow booth at SPS 2024
    Events & Webinars

    Stay connected with Watlow through a variety of events, including upcoming trade shows, webinars, corporate and community involvement activities.

    Learn More

    Product Documents

    Watlow Catalogs Specification Sheets User Manuals Software and Demos Brochures
    CAD Drawings Mobile Applications Watlow Patents Certifications & Approvals Retrofit Guides

    Tools and Calculators

    Wattage Calculator Ohm's Law Calculator 3-Phase Delta / Wye Calculator Glossary Equations Reference Data

    Customer Service Documents

    Invoice Payment Options Supplier Requirements Environmental Polices and Statements Copyright and Trademark Information Certifications & Approvals Policies Return Materials Authorization (RMA)

    Knowledge and Insights

    thumbnails of white papers relating to electrification and decarbonization
    White Papers
      Browse White Papers
    Tech Tips logo
    Tech Tips
      Browse Articles

    CMRT/EMRT & Russian Material Disclosure

    Conflict/Extended Mineral Russian Material Disclosure [.PDF]

    Events

    Watlow & Eurotherm tradeshow booth at SPS 2024
    Events & Webinars

    Stay connected with Watlow through a variety of events, including upcoming trade shows, webinars, corporate and community involvement activities.

    Learn More
  • Careers

    Careers

    Careers
    Career Opportunities

    Are you looking for an opportunity to make a great living and be part of a thriving cross functional community? Select an option below to view opportunities in your region.


    View Openings
    United States Europe Asia Mexico
    STM
    Student Programs
    At Watlow®, we recognize the importance of learning, experimenting, and building your career. Our student programs are a great way for you to gain hands-on experience and on-the-job learning from the start. Learn More

    Career Opportunities

    View Openings
    United States Europe Asia Mexico
    STM
    Student Programs
    At Watlow®, we recognize the importance of learning, experimenting, and building your career. Our student programs are a great way for you to gain hands-on experience and on-the-job learning from the start. Learn More
  • English
    • Español
    • Français
    • Italia
    • Dutch
    • 中文
    • Deutsch
  • Contact Us
    • Contact Watlow
    • Locate a Partner

Search

  1. Tech Tips
tech tips blog logo

What is Heater Bakeout and Why is it Important?

Popular tags: Power Controllers Power Control ASPYRE® Intelligent Power Controller

By: Admin on May 06, 2021

Download Share

 

Watlow® has encouraged customers for many years to perform moisture tests on heaters before use. The process of conditioning or “baking out” a heater can be a costly and complex process requiring additional equipment. However, failure to perform this critical step prior to applying full power to a heater could have catastrophic effects if moisture is present.

Watlow controllers offer a new feature designed to expedite this process ensuring that your heaters are ready when you need them. Our built-in heater bakeout functionality provides users with the confidence needed to operate their process without the hassle and additional expense associated with conditioning ovens. It is an important advancement that continues to show the world-class engineering expertise of Watlow’s team.   

The moisture problem with heaters

A common issue with heaters is the likelihood of moisture being drawn into the element from the atmosphere. This phenomenon typically occurs when heaters are stored for an extended period prior to use. Metal sheath heaters are hygroscopic, meaning that they will absorb moisture from the surrounding atmosphere. When enough moisture has accumulated in the heater, a condition known as a “wet heater” will occur. Wet heater problems are more common in locations with relative high humidity, but they can also occur if heaters are stored and unused for extended periods of time (about 30 days).

In some instances, heaters can become so “wet” that it is possible to observe water exiting the heater during a conditioning cycle. In addition to location, higher line voltage heaters and large process heater bundles are more prone to absorbing moisture.

How moisture is absorbed by a heater

Water forms in a heater through natural chemical and atmospheric processes. Take a tubular mineral insulated heater, for example. Magnesium oxide is used as insulation in a tubular mineral insulated heater because it has high thermal conductivity and low electrical conductivity. The chemical compound is used to transfer heat from the element to the sheath.

Magnesium oxide readily absorbs moisture to form magnesium hydroxide. As the unit cools after use, the pressure inside the heater falls and air is driven into the heater. Once inside, the moisture in the air can exist as dihydrogen monoxide – commonly known as water – in liquid or vapor form, or as magnesium hydroxide.

How to check for a wet heater

If a user suspects a wet heater is present or is unsure, it is best to run a meg-ohm precheck on the heater to avoid potential damage to the heater. A meg-ohm precheck is conducted with a Megger test instrument, which provides a measure of insulation resistance in ohms or meg-ohms. A lower Megger reading indicates that the user should condition the heater prior to use. Please refer to the installation and maintenance manual provided with your heater for the recommended meg-ohm level prior to applying full power to your heater.

Other indications that moisture may be present in the heater include tripping the ground fault circuit interrupter (GFCI), the heater element experiencing a “burn through” fault, high speed fuses open in the power controller and branch circuit fuses or circuit breakers open.

How to remove water from a heater

If moisture is in the heater, the concentration of magnesium hydroxide will increase as the temperature rises. At 100 degrees Celsius, the chemically bonded water is maximized. As the temperature increases to more than 330 degrees Celsius, the magnesium hydroxide starts to decompose. At 430 degrees Celsius, the chemical compound is converted back to magnesium oxide and water.

A “bakeout” process is used to remove this moisture. A bakeout is the use of high temperature and sometimes a vacuum to remove moisture or water vapor from the heater. A bakeout artificially accelerates a process known as outgassing, which is the release of water vapor trapped or absorbed in the heater.

Heater conditioning can be an expensive, complicated process. In its simplest form, a conditioning process is performed by placing the heater in a specialized oven running at 120 degrees Celsius for up to 40 hours. Some heaters require only a cycle of six to eight hours. After the cycle is complete, the heater should be retested with a Meggers instrument to determine if the required meg-ohm level has been attained.

It is important to note, the moisture released from within the magnesium oxide does not appear to contribute to the heater failure. As such, 120 degrees Celsius is sufficient to remove water from the heater and is a safe temperature for the other components of the heater, including terminations, wires and seals.

A new, built-in bakeout solution

Watlow now offers heater bakeout feature in several of our control devices. This feature protects the heater upon startup by removing excess moisture from inside the heater before applying full power, safeguarding the heater from permanent damage.

Watlow’s ASPYRE DT® SCR smart power controller is one such device with the built-in heater bakeout option. With a 9,999-minute program, ASPYRE power switches are designed such that the current setting will determine the max root mean square (RMS) heater current that can be reached at the end of the bakeout. A bakeout can be initiated if enough time has passed since the heater was last operational. In addition, a bakeout will activate after a power cycle of the controller. Watlow’s F4T® multi-function controller also offers a heater bakeout function.

Power controllers with built-in heater bakeout illustrates Watlow’s commitment to its customers of providing superior products and services to meet their unique business needs. With this innovation, customers can improve performance and efficiency by eliminating the need to test for or condition wet heaters. Let Watlow’s experience in numerous industries assist you, and visit our power controller product page or contact a Watlow sales representative to learn more.

 

Related Topics

Power Controllers
Power Control
ASPYRE® Intelligent Power Controller
Back to top
About Us
  • Core Values
  • Environmental Sustainability
  • Social Responsibility
  • Governance
  • Watlow Worldwide
  • Company History
  • News
Contact Us
  • Submit an Inquiry
  • Locate a Partner
  • Locate a Sales Office
  • Application Assistance
  • e-Solutions Login
Industries We Serve
  • Heat Treatment
  • Energy and Environmental Technologies
  • Semiconductor Processing
  • Clinical Equipment
  • Foodservice Equipment
  • Life Sciences
Resources & Support
  • Customer Service & Support
  • Engineering Tools
  • Technical Library
  • Know Your Rights: Workplace Discrimination is Illegal
  • OFCCP Pay Transparency Non-Discrimination Provision
  • Environmental Product Information Request Portal
    • Core Values
    • Environmental Sustainability
    • Social Responsibility
    • Governance
    • Watlow Worldwide
    • Company History
    • News
    • Submit an Inquiry
    • Locate a Partner
    • Locate a Sales Office
    • Application Assistance
    • e-Solutions Login
    • Heat Treatment
    • Energy and Environmental Technologies
    • Semiconductor Processing
    • Clinical Equipment
    • Foodservice Equipment
    • Life Sciences
    • Customer Service & Support
    • Engineering Tools
    • Technical Library
    • Know Your Rights: Workplace Discrimination is Illegal
    • OFCCP Pay Transparency Non-Discrimination Provision
    • Environmental Product Information Request Portal
Policies Privacy Policy Terms of Use Data Protection Policy - GDPR
© 2025 Watlow Electric Manufacturing Company. All Rights Reserved.