How to Identify Your Hotwatt Heater

How to Identify Your Hotwatt Heater

Know Which Heater You Need When It’s Time to Replace It 

All good things must come to an end—and Hotwatt heaters are no exception. While our heaters are known for their exceptional quality, longevity, and robustness, they do have a shelf life. When the time comes to replace your Hotwatt heater, the following guide will help you to identify which heater you have.


All Hotwatt heaters are marked with codes to help identify each unit. These codes start with a prefix, which identifies the product line. This is the first step in identifying your heater.

Prefix Codes:

AH – Air Heater

AT – Metal Sheathed Glasrope® Heater

CB – Ceramic Heater

CK – Crank Case Heater

CS – Ceramic Insulated Strip Heater

CT – Locker Heater – Medium Screw Base

DH – Drum Heater (standard)

DT – Drum Heater (tubular)

EM – Immersion Heater

FH – Foil Rope Heater with Fiberglass Sleeve

FM – Flexible Metal Sheathed Rope Heater

FS – Finned Strip Heater

FT – Finned Tubular Heater*

GH – High Temp Glasrope® Heater

GR – Glasrope® Heater

GS – Silicone Rubber Rope Heater

HA – Heavy Duty Air Heater

HS – Superwatt® Cartridge Heater

MA – Maxi Flow Air Heater

MB – Mica Band Heater

MH – Metric Superwatt® Cartridge Heater

MS – Metric Standard Cartridge Heater

OT – Open Coil Heater – Medium Screw Base

PF – Pure Flow Air Heater

PH – Plate Heater

SC – Standard Cartridge Heater

SR – Rectangular Cartridge Heater

SS – Square Cartridge Heater

ST – Mica Strip Heater

WB – Special Immersion Heater

Descriptions of the Unit

The next step is to identify the shape, diameter, voltage, and wattage. Examples are provided below for round, square, and rectangular units. 

Round Units 


The number directly after the prefix is the OD (outside diameter) of the element. In the above case, this is a standard cartridge at .625” OD (or 5/8”).

Next, length is added to the description as shown below:


The above means a 5/8” OD standard cartridge at 12” long.

Additional to that, we add the wattage and voltage as shown below:


The above is a 5/8” OD at 12” long @ 400 watts, and 120 volt.

Some units are now being marked with our internal 12-digit code versus the above. This is a unique number to identify every unit that gets applied to a customer order.


SC0620250031 (12 digit)

SC62-2.5/150W220V/SF1-18 (corresponding description)

The 12-digit code reads as: SC (standard cartridge); 062 (outside diameter); 025 (2.5” long); and the 0031 is only internal (to Backer Hotwatt).

Lead and termination styles are denoted by the SF suffix on the description on all elements. For example, SF1-18 equals 18 inches of flex leads.

Square (SS) or Rectangular (SR) Cartridge Units 


The same nomenclature applies as round, but uses width and thickness (height) versus outside diameter. Both descriptions or 12-digit codes could be etched. You start with a prefix.

For example, SS12-1. This is a square cartridge heater with a 1/8” width (.125”) at 1” long. Each width has a standard thickness associated with it. In the above case, SR12-1 has a 1/8” width and a 1/8” thickness.

All 1/8” wide units have a 1/8” thickness. An SS-12-1 is 1/8” thick and 1/8” wide and 1” long. All square units have matching thickness and widths. 3/16” is 3/16”, 1/4” is 1/4”, etc.


SS0180287000 (12 digit)

SS18-2.87/100W120V/SF4-36/ (description)

The 12-digit code reads as:

SS018 (Square, 3/16” x 3/16”) 0287 (2.87” long); the remaining digits are internal. 


The same nomenclature applies as square, but the width and thickness. The thickness varies.

SR13s are all 1/8” x 3/8” with length as a variable (i.e., SR13-6 is a 6” long unit with the aforementioned dimensions).

SR14s: All 1/8” x 1/4”

SR15s: All 1/4” x 5/8”

SR16s: All 1/4” x 1”


SR0160200005 (12 digit)

SR16-2/200W120V/SF1-72 (description)

The 12-digit code reads as:

SR016 (Rectangular, 1/4” x 1”) 02 (2” long) remaining digits are internal

We Can Help

We are here to help with any of your cartridge, air process, immersion, strip and finned strip, tubular and finned tubular, band, foil, flexible Glasrope®, crankcase, and ceramic heater needs. Contact Backer Hotwatt today about your heating application and any questions you may have about the heater you need when it’s time for a replacement.