Facts About Enclosure Heaters

Frequently Asked Questions on Enclosure Heaters

What is an enclosure heater?

Electrical enclosures or cabinets often require heating elements to maintain temperatures in the enclosure for proper operation of the electrical devices and equipment.  These heaters raise the temperature within the enclosure to reduce humidity and moisture, keep components from freezing, and condition external air entering the enclosure.

Condensation and corrosion are mortal enemies of electronic components and circuitry.  Rapid changes in external and internal temperatures can cause condensation to form directly on components.  Opening the door to an enclosure for maintenance can introduce cool air and moisture requiring heating adjustments.

Enclosures can contain components such as valves, scales, and measuring devices for gas, oil, food production, medical devices, specialized fuels & gases, and other fluids.  The devices controlling the flow and metering need to maintain an optimum temperature for performance.  Freeze protection of electronic devices and controls is a real concern with enclosures located remotely.

What type of heaters are used in control cabinets and enclosures?

The type of heater used for heating is determined by the size of the enclosure, the temperature required, power, and safety requirements.  Small cabinets housing electrical components for medical devices or aerospace applications use small heaters at low voltage with minimum control circuit requirements such as PTC ceramic element heaters.

Small enclosures and enclosures in hazardous areas require special consideration on what type of heating elements are used.

Larger cabinets may use PTC heating elements incorporated into convection or forced air assemblies providing more heat and circulation within the cabinets.  The larger the cabinet, the higher the power output required for heating the larger area.

Enclosures with higher heat and power requirements can use tubular heaters operating on 120-240 V.  These tubular heaters are enclosed in metal guards for mounting and touch protection from the heating element.

Mounting options and examples of heaters for enclosures

Heaters are designed for mounting on DIN rails.  These rails affixed to the back walls of most enclosures are used for mounting most of the electronic components and other devices found in electrical control cabinets.  Utilizing these rails makes it a simple and convenient way to mount the electrical heaters.

What are the different types of heaters used in enclosures?

Some of the more common types of heaters that vary in power output and voltage inputs are:

• Fan heaters
• PTC Fan Heaters are designed for focusing airflow in compact
  
  spaces that require precise heating and moisture control.
• DBK fan heaters range from 10W to 800W, 12-24V in select models,115-230V heaters, and an independent 12-24-volt circuit for the fans allowing them to operate separately without the heaters. 
• This lightweight high-power to size ratio components are pre-wired ready for installation on DIN Rails. 

• Convection heaters
• PTC Convection Heaters are designed for focusing heat in compact
  
  spaces that require precise heating and moisture control.  These heaters are used in applications where there isn’t room or separate power for a fan or the temperatures range too low for fan operation. 
• DBK convection heaters range from 20W to 240W, 110-240V heaters. These lightweight high-power to size ratio components are ready for installation on DIN Rails. 

• Surface heaters
• PTC surface heaters are enclosed in housings designed to transfer
  
  their heat to an adjoining surface.  These dynamic heating elements combine the functions of heating and temperature control in one element.
• Are you an electrical, mechanical, or industrial engineer looking for a focused heating solution for your equipment or cabinet? 
• The HP Series heating components are embedded in an aluminum housing providing a strong design and excellent heat transfer characteristics.  Each comes prewired and predrilled for easy installation. 

• Cartridge heaters
• PTC cartridge heaters are dynamic heating elements that combine
  
  the functions of heating and temperature control in one element. 
• Cartridge heaters are used when the heat needs to be transferred directly to material inside a container or vessel. They are inserted through the wall of the vessel or into a hole to reach the material to be heated.
• The PSA Series heater is embedded in an aluminum housing providing a strong design and excellent heat transfer characteristics.  Each is pre-wired for easy installation. 
• The series comes in a range of 11W (max) to 113W (max) wattage's depending on the configuration with voltages from12-24V or 110-240V.  Surface temperatures range from 176 – 392 degrees F depending on the wattage and size selected.

• Flexible heaters
• flexible heaters can bend and contour to your specific application
  
  requirements. They can be attached to flat or curved surfaces to allow for a better and more effective transfer of heat.
• The ability to affix the heaters directly onto the surface they are heating makes them ideal for equipment where standard operating conditions would prevent usage of conventional heating methods.
• Heating elements encapsulated in silicone rubber are flexible and provide protection against moisture, chemicals, and are often more robust than other heating solutions.  Silicone offers high electrical insulating properties and is also tolerant of a wide range of temperature extremes. 

• Tubular heaters

• Tubular heaters are used in a large variety of applications. 

  
• High power density and installation advantages offer solutions for applications requiring high consistent heat such as outside enclosures during winter temperatures.
• The elements can be adapted extensively to the demands. There are various tube jacket materials available to match different requirements.

• Air heaters
• PTC finned air heaters are specially designed to heat a large
  
  volume of air. The fins or honeycomb structure of the heater allows for efficient heat transfer into the air stream through the heater.
• DBK standard HRKK air heaters have V-shaped fins, and our newer HRP models are fully insulated and offer an option for Delta (D) shaped fins to provide high heat output with minimal pressure loss.
• The HR family of heaters uses PTC which has a temperature limiting effect, this provides an additional safety feature with little chance of combustion to surrounding surfaces.  

Are there other devices used in addition to heaters for controlling the enclosure environment?

Thermoelectric coolers, condensate evaporators, temperature, and humidity controls can be used in conjunction with enclosure heaters.

• Thermoelectric Coolers
• Thermoelectric Air-to-Air Cooler is an ideal choice for design
  
  engineers that need a solid-state cooler with compact design and DC operation. 
• These coolers employ forced air convection by utilizing IP54 axial fans. The standard range for these assemblies is 60W to 200W. The coolers are ETL recognized and RoHS compliant

• Condensate evaporators
• An electronic condensate evaporator uses PTC heater technology
  
  for reliability and low power consumption removing condensation inside air-condition cabinets and refrigerators.  
• The evaporator includes inlet and outlet ports for condensate such that no draining of the accumulated water is necessary.

• Temperature controls
• DBK offers controls to complement its PTC heaters and
  
  thermoelectric cooling devices. 
• These products include adjustable thermostats, fixed value thermostats, and electrical mechanical hygrostats. 
• The controls come in low and high-voltage models to fit a wide variety of design requirements. All are compactly designed to fit in tight spaces.
• Temperature ranges vary with products and voltage.

What size of enclosure heater is needed?

Determining the dimensions of the cabinet or enclosure is a good place to start sizing the heater.  Height, width, and depth of the enclosure equal the volume requirement.  The density of the electrical components and instrumentation is also taken into account.

Mounting of the enclosures matters.

• Is the cabinet wall mounted or stand-alone?
• The first or last of interconnected cabinets?
• Center cabinet?
• Indoor or outdoor?
• Openings for airflow?
• Conduits connections for wire or piping?

Construction material matters because they conduct heat and cooling at different rates.

• Stainless steel
• Painted steel
• Aluminum
• Polyester

The required temperature difference between outside and inside the enclosure

If the enclosures are outside exposed to harsh weather conditions or indoors in a controlled environment makes a big difference in sizing the heater.  Indoor panels won’t require as much heating as outdoor panels in the wintertime.

Electrical components and control devices can freeze in outdoor environments.  The numerous ATMs, parking, and ticket devices require heat for operation and printing tickets or receipts.  

Remote gas and oil field enclosure need to operate controls and valves in extreme weather conditions. 

Enclosure aboard ships and sea, planes, rockets, and even satellites need dependable heating devices for proper operation.

Are there calculators available to determine heating power requirements?

Many manufacturers provide online calculators to estimate the heating power requirements for your enclosures based on the previous facts.  DBK USA cabinet heater selector is a good example.

Once you find the estimated power requirements you should check with an enclosure heating expert to find what devices will provide the power output in that range.  If you just have general questions call DBK USA industrial heating expert at 1-864-607-9047.